Which QT Correction Formulae to Use for QT Monitoring?

Polygenic risk score for drug-induced long QT syndrome: independent validation in a real-world patient cohort

OBJECTIVE

Drug-induced long QT syndrome (diLQTS) is an adverse reaction from over 150 FDA-approved medications, posing the risk of triggering torsades de pointes and sudden death. While common genetic variants may modestly impact QT interval individually, their collective effect can significantly amplify risk of diLQTS. Consequently, this study aimed to validate a polygenic risk score (PRS) for diLQTS previously proposed by Strauss et al .

METHODS

A retrospective cohort study was conducted utilizing patients from the Michigan Genomics Initiative prescribed 27 high-risk QT-prolonging drugs and an ECG during the prescription. The primary outcome was marked prolongation of the QTc interval (either >60 ms change from baseline or >500 ms absolute value) during treatment with a high-risk QT-prolonging drug.

RESULTS

The primary outcome occurred in 12.0% of n  = 6070 self-reported White, 12.4% of 558 African American, and 8.2% of 110 Asian patients. The PRS significantly associated with diLQTS in White patients [adjusted odds ratio = 1.44 (95% CI: 1.09-1.89); P  = 0.009]. However the study lacked sufficient statistical power to confirm the PRS as a risk factor in African Americans [adjusted odds ratio = 2.18 (95% CI: 0.98-5.49); P  = 0.073] and Asians [adjusted odds ratio = 3.21 (95% CI: 0.69-16.87); P  = 0.139] due to smaller sample sizes in these groups.

CONCLUSION

The previously published PRS for diLQTS was validated in a large, real-world cohort, demonstrating its potential as a tool for identifying high-risk patients. Incorporating this PRS into routine clinical practice could enable proactive measures to prevent life-threatening diLQTS.

Temporal variations in QTc interval during and after COVID-19 infection: a retrospective study

OBJECTIVE

The aim of this study was to investigate the dynamic changes in QTc interval duration among patients with COVID-19 infection before, during, and after infection, in order to assess the short- and potential long-term impact of COVID-19 on cardiac electrophysiology.

METHODS

A retrospective analysis was conducted on 303 inpatients diagnosed with COVID-19 who visited a tertiary Grade A hospital in China between August 2022 and December 2023. Inclusion criteria required patients to have at least two electrocardiogram (ECG) recordings at three specific time points: before COVID-19 infection, during acute infection, and after recovery (more than one month post-infection).

RESULTS

The mean age of participants was 72.8 ± 14.7 years, with a male preponderance (62%, n = 188). A significant prolongation of QTc interval was observed during COVID-19 infection compared to pre-infection levels (438.3 ± 26.7 ms vs. 433.9 ± 26.6 ms, p = 0.025). QTc interval was positively correlated with age both before (r = 0.23, p = 0.001) and during infection (r = 0.19, p = 0.001). In short-term follow-up (≤ 6 months), QTc interval remained unchanged from the infectious period (p > 0.05), whereas it significantly decreased during long-term follow-up (> 6 months; 429.6 ± 32.5 ms vs. 437.5 ± 28.2 ms, p = 0.002). Additionally, P-wave duration significantly decreased from the infectious period to long-term follow-up (99.5 ± 14.8 ms to 96.4 ± 15.2 ms, p = 0.024).

CONCLUSIONS

COVID-19 infection demonstrated a significant correlation with prolonged QTc interval, persisting in the short term but gradually returning to normal in the long term. Similarly, P-wave duration shortened over time, suggesting potential cardiac electrophysiological recovery.

CLINICAL TRIAL NUMBER

Not applicable.

Intraoperative QTc interval interpretation: Effects of anaesthesia, ECG, correction formulae, sex, and current limits: A Prospective Observational Study

BACKGROUND

Severe QT interval prolongation requires monitoring QTc intervals during anaesthesia with recommended therapeutic interventions at a threshold of 500 ms. The need for 12-lead ECG and lack of standardisation limit such monitoring. We determined whether automated continuous intraoperative QTc monitoring with 5-lead ECG measures QTc intervals comparable to 12-lead ECG and whether the interpretation of QTc intervals depends on the correction formulae and the patient's sex. We compared intraoperative QTc times to QTc times from resting ECGs of a population from the same region, to substantiate the hypothesis that patients under general anaesthesia may need specific treatment thresholds.

METHODS

In this prospective observational study, intraoperative QT/QTc intervals were automatically recorded using 12 and 5-lead ECG in 100 patients (44% males). QTc values were analysed for sex and formula-specific aspects after correction for heart rate according to Bazett, Fridericia, Hodges, Framingham, Charbit and QTcRAS, and compared to a regional community-based cohort. The level of significance was set to α = 0.05.

RESULTS

QT interval duration was not significantly different between 12-lead and 5-lead ECG (difference - 0.09 ms ± 8.5 ms, p = 0.793). The QTc interval duration significantly differed between the correction formulae (p < 0.001) and between sexes (p < 0.001). Mean intraoperative QTc duration was higher than in resting ECGs from a large community-based population with the same regional background (438 vs. 417 ms). The incidence of prolonged values >500 ms significantly depended on the correction formula (p < 0.001) and was up to tenfold higher in women versus men.

CONCLUSION

Intraoperative QTc interval measurement using a 5-lead ECG is valid. Correction formulae and gender influence the intraoperative QTc interval duration and the incidence of pathologically prolonged values according to current limits. The consideration and definition of sex-specific normal limits for QTc times under general anaesthesia, therefore, warrant further investigation.

Updated treatment guidelines for drug-resistant TB: how safe are clofazimine-based regimens?

In June 2024, WHO released 'Key updates to the treatment of drug-resistant tuberculosis: rapid communication', after the preliminary publication of results from two clinical trials: 'BEAT-Tuberculosis' and 'endTB'. All proposed regimens include clofazimine (Cfz). However, a recent paper has reported a high incidence of QTc prolongation among patients receiving Cfz-based treatment for multidrug-resistant TB in Taiwan. Here, we discuss the cardiac safety of Cfz and the role of active drug safety monitoring at the programme level in collecting information on this issue.

Relevance of accurate QT correction in the assessment of long QT syndrome

BACKGROUND

Long QT syndrome (LQTS) is a genetic cardiac disease, where the corrected QT (QTc) interval is prolonged. It can cause arrhythmias and lead to a sudden cardiac death. Duration of the QT interval depends on the heart rate and this dependency is treated with QT correction. However, the current QT correction methods have well known problems and limitations.

OBJECTIVE

We study the relevance of QT correction method in evaluating the risk of LQTS. We evaluate the reliability of the present and recently developed QT correction methods to discriminate LQTS subjects from healthy controls.

METHODS

We use the clinically prevalent QT correction methods, particularly Bazett and Fridericia, in comparison with the recently developed AccuQT method. The data of healthy controls and LQTS subjects is extracted from the Rochester THEW database. The analysis accounts for sex, major LQTS subtypes, and beta-blocker treatment.

RESULTS

QT values corrected with AccuQT discriminate the healthy and LQTS samples with the best accuracy, leading to (TP, TN) = (0.87, 0.65) with the conventional 450 ms threshold for LQTS. Fridericia correction yields lower sensitivity (0.71), but comparable balanced accuracy, whereas Bazett shows significantly less accurate results due to overcorrection at lower heart rates.

CONCLUSION

The selected QT correction method is important in the identification of LQTS. In particular, the use of Bazett correction should be questioned. Fridericia correction yields good results with respect to its simplicity. AccuQT has the best accuracy out of all the methods for LQTS discrimination. For practical applicability, however, AccuQT needs further validation in realistic clinical conditions.

Optimal QT Correction Formula for Older Chinese: Guangzhou Biobank Cohort Study

INTRODUCTION

To identify the optimal QT correction formula for generating corrected QT (QTc) and cutoffs for prolonged QTc, and examine the associations with mortality and cardiovascular disease (CVD) in older Chinese.

METHODS

A prospective study included 24,611 Chinese aged 50+ years and without CVD at 2003-2008 from Guangzhou Biobank Cohort Study. QT interval was corrected by Bazett, Fridericia, Framingham and Hodges formulas. The slope and R2 of the QTc and heart rate regression were used to determine the optimal correction formula. The 95th percentile of QTc was used to defined prolonged QTc. Cox regression was used to examine associations of prolonged QTc with mortality and CVD. The net reclassification index was calculated to assess risk reclassification.

RESULTS

During an average follow-up of 15.3 years, 5,261 deaths and 5,539 CVD occurred. Optimal heart correction was observed for the Hodges formula, and Bazett formula performed the worst. Prolonged QTc corrected by Fridericia, Framingham and Hodges formulas had similar association strength with all-cause mortality, CVD mortality and incident CVD (especially coronary heart disease, myocardial infarction and ischemic stroke), with hazard ratios approximately being 1.25, 1.40, and 1.15, respectively. They also improved risk reclassification for all-cause mortality, CVD mortality and incident CVD by approximately 5%, 10%, and 6%, respectively. However, prolonged QTc corrected by Bazett formula was not associated with incident CVD and did not improve risk reclassification.

CONCLUSIONS

Hodges formula outperformed other formulas for heart rate correction. Fridericia, Framingham, and Hodges formulas can be used for death and cardiovascular risk prediction.

The Effects of Pediatric Acute Lymphoblastic Leukemia Treatment on Cardiac Repolarization

Background: In recent years, cardiac dysfunction in childhood cancer survivors has become an important issue. Studies are focusing on identifying means for the early identification of patients at risk. Considering this, our study aims to investigate 24-hour Holter electrocardiogram (ECG) repolarization changes throughout doxorubicin (DOX) and cyclophosphamide (CPM) administration in pediatric patients treated for acute lymphoblastic leukemia (ALL). Methods: This was an investigator-driven, single-center, prospective, observational study. Enrolled children had a baseline bedside ECG examination performed before starting chemotherapy (T0). Serial Holter ECG examinations were conducted at three moments during their treatment protocol: day 8 (T1), day 29 (T2), and day 36 (T3). This study evaluated several ECG repolarization parameters, such as the QT interval, corrected QT interval (QTc), and QTc dispersion, as well as ST segment variations. Results: We evaluated 37 children diagnosed with ALL. The T0 examination revealed that over a third of patients had a resting heart rate (HR) outside the normal range for their age and sex. During chemotherapy, statistically significant increases in both HR as well as QT and QTc dispersion values were noticed, especially during the first DOX administration. What is more, a significant increase in the percentage of patients with ST segment depression from T1 to T2 and T3 was noticed. Rhythm disturbances were rare in the study population, with only a few patients presenting ventricular or supraventricular extrasystoles. Conclusions: This study reveals silent repolarization changes occurring early during anticancer treatment in children treated for ALL. These findings could aid in a better understanding of the cardiac toxicity mechanism, and they could potentially improve cardiac risk stratification for oncologic patients. Because of the small number of patients, our results need to be validated by larger studies.

The Best ECG Lead for Predicting the Risk of Drug-Induced Torsade De Pointes Using Corrected QT Interval: A Comparative Prognostic Study

Introduction

Torsade de pointes (TdP) is a deadly complication from drug-induced QT prolongation. Each of the 12 lead of an electrocardiogram (ECG) has a different length of QT interval, and thus might have a different performance in TdP prediction. This study aimed to determine the best ECG lead or set of leads in this regard.

Methods

This is a comparative prognostic accuracy study using a two-gate data gathering design. The population in this study was from two sources, a case group (Patients who had drug-induced TdP, which were identified through a systematic Medline search) and a control group (those who overdosed on QT-prolonging drugs, which included patients who were under the consultation of Medical Toxicology Services). The areas under the receiver operating characteristic curve (AUROC) of heart rate-corrected QT (QTc) in each single ECG lead and of a mean/median QTc from a set of ECG leads (17 index test) in predicting the risk of TdP were calculated and compared with each other, trying to find the best lead for this propose. QTc Interval measurements were done by four investigators (Interrater reliabilities 0.95).

Results

Finally, we included 136 and 148 ECGs from TdP cases and controls, respectively. V3 lead had the highest frequency of longest QTc interval, among the leads. The lead having the longest QTc yielded the greatest AUROC in predicting TdP regardless of QT correction formulas (QTcFRA=0.9915, QTcRTH=0.9893, QTcBZT=0.9904). The mean QTc of 3 leads (lead II, plus any two of leads V2-V4), and a median QTc of 6 leads (I, II, aVF, V2, V4, V6) provided similar overall performance for TdP prediction (regardless of the type of QTc formula).

Conclusion

The longest QTc provided the greatest AUROC in predicting drug-induced TdP, however, the longest QTc is not located in a fixed individual lead in any patient. A less time-consuming method with comparable performance to that of the longest QTc was to use a mean QTc from 3 leads (lead II, plus any two of leads V2-V4). The potential clinical impact of this finding needs to be verified in a prospective cohort study.

An Updated Safety Review of the Relationship Between Atypical Antipsychotic Drugs, the QTc Interval and Torsades de Pointe As: Implications for Clinical Use

INTRODUCTION

The rising prevalence of psychiatric disorders has resulted in a significant increase in the use of antipsychotic medications. These agents may prolong the corrected QT interval (QTc), running the risk of precipitating ventricular arrhythmias, notably Torsades de Pointes (TdP). Current recommendations vary regarding the optimal approach to safe prescribing practices and QTc surveillance for antipsychotics. This review summarizes the current literature addressing these clinical concerns.

AREAS COVERED

The physiologic basis of the QTc interval, mechanisms underlying its susceptibility to pharmacological influence, specific risks associated with atypical antipsychotic agents, and recommendations for safe prescription practices. We performed a literature review using Pubmed and Embase databases, searching for 'antipsychotics' and 'torsades de pointes.'

EXPERT OPINION

Finding a safe and universally accepted protocol for prescribing antipsychotics remains a persistent challenge in medicine. Predictive models that integrate clinical history with demographic and ECG characteristics can help estimate an individual's susceptibility to therapy-associated risks, including QTc prolongation. Agents such as ziprasidone and iloperidone are significantly more likely to prolong the QTc interval compared to others such as brexpiprazole, cariprazine, olanzapine, and clozapine. A personalized approach using low-risk medications when clinically feasible, and at the lowest efficacious dose, offers a promising path toward safer antipsychotic prescribing.

Comparison of electrocardiogram parameters and echocardiographic response between distinct left bundle branch area pacing modes in heart failure patients

Background

Left bundle branch area pacing (LBBAP) has become an alternative method for cardiac resynchronization therapy. Various modes of LBBAP have been determined, including left bundle trunk pacing (LBTP), left anterior branch pacing (LAFP) and left posterior branch pacing (LPFP). However, whether the outcomes of various pacing modes differ in heart failure (HF) patients is still unclear. This study aimed to compare the electrophysiological characteristics and echocardiographic response rate among those distinct modes of LBBAP.

Methods

HF patients undergoing successful LBBAP were retrospectively included. Distinct modes of pacing were determined based on paced QRS morphology. The fluoroscopic images were collected to compare the lead tip position between the groups. The electrocardiograms (ECG) before and after LBBAP were used to measure the depolarization (QRS duration [QRSd] and the interventricular delay [IVD]), and the repolarization parameters [QTc, TpeakTend(TpTe), and TpTe/QTc]. The left ventricular ejection fraction (LVEF) and left ventricular end-diastolic diameter (LVEDD) of patients were also recorded. In addition, the lead parameters and certain complications were compared.

Results

A total of 64 HF patients were finally included, consisting of 16 (25.0%) patients in the LBTP group, 22 (34.4%) patients in the LAFP group, and 26 (40.6%) patients in the LPFP group. The distribution features of LBBAP lead tips were significantly related to pacing modes: LBTP was more likely to be in zone 4 while LAFP or LPFP was prone to locate in zone 5. After LBBAP, the ventricular ECG parameters were significantly improved, regardless of pacing modes. Besides, the LVEF of the patients was significantly increased (P < 0.001), and LVEDD was significantly decreased (P < 0.001). There was no difference in the response rate and super-response rate among groups (P > 0.05). In addition, the lead parameters remained stable and no significant difference was observed among groups.

Conclusion

LPFP was the main pacing mode among HF patients after LBBAP. The paced QRS morphology was significantly related to the position of lead tips. After LBBAP, the ventricular depolarization synchronization and repolarization stability were both significantly improved, regardless of pacing modes. There was no significant difference in the echocardiographic response rate among distinct LBBAP modes.

Hydroxychloroquine and Chloroquine-Induced Cardiac Arrhythmias and Sudden Cardiac Death in Patients With Systemic Autoimmune Rheumatic Diseases: A Systematic Review and Meta-Analysis

ABSTRACT

Hydroxychloroquine (HCQ) and chloroquine (CQ) are foundational treatments for several systemic autoimmune rheumatic diseases, including systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA). Concerns regarding the risk of cardiac arrhythmia and death have been raised, yet the burden of HCQ and CQ-related cardiac toxicities remains unclear. A systematic literature search was conducted in the MEDLINE and Embase databases for articles published between the earliest date and April 2023 reporting cardiac conduction abnormalities in patients with systemic autoimmune rheumatic diseases taking HCQ or CQ. Meta-analysis was performed to calculate the difference in mean corrected QT (QTc) interval and odds ratio of prolonged QTc interval in those taking HCQ or CQ versus not. Of 2673 unique records, 34 met the inclusion criteria, including 70,609 subjects. Thirty-three studies reported outcomes in HCQ and 9 in CQ. Five studies reported outcomes in RA, 11 in SLE, and 18 in populations with mixed rheumatic diseases. Eleven studies reported mean QTc and OR for prolonged QTc for meta-analysis, all reporting outcomes in HCQ. There was a significant increase in mean QTc (10.29 ms,  P  = 0.458) among HCQ users compared to non-HCQ users in patients with RA. There was no difference in mean QTc between HCQ and non-HCQ users in other systemic autoimmune rheumatic diseases. When rheumatic diseases were pooled, HCQ users were more likely to have prolonged QTc compared to non-HCQ users (odds ratio 1.57, 95% CI, 1.19, 2.08). The results of this study suggest that clinicians should be aware of potential adverse cardiac events of HCQ and consider QTc monitoring for patients on HCQ for the treatment of systemic autoimmune rheumatic diseases.

Antiarrhythmic Mechanisms of Epidural Blockade After Myocardial Infarction

BACKGROUND

Thoracic epidural anesthesia (TEA) has been shown to reduce the burden of ventricular tachycardia in small case series of patients with refractory ventricular tachyarrhythmias and cardiomyopathy. However, its electrophysiological and autonomic effects in diseased hearts remain unclear, and its use after myocardial infarction is limited by concerns for potential right ventricular dysfunction.

METHODS

Myocardial infarction was created in Yorkshire pigs (N=22) by left anterior descending coronary artery occlusion. Approximately, six weeks after myocardial infarction, an epidural catheter was placed at the C7-T1 vertebral level for injection of 2% lidocaine. Right and left ventricular hemodynamics were recorded using Millar pressure-conductance catheters, and ventricular activation recovery intervals (ARIs), a surrogate of action potential durations, by a 56-electrode sock and 64-electrode basket catheter. Hemodynamics and ARIs, baroreflex sensitivity and intrinsic cardiac neural activity, and ventricular effective refractory periods and slope of restitution (Smax) were assessed before and after TEA. Ventricular tachyarrhythmia inducibility was assessed by programmed electrical stimulation.

RESULTS

TEA reduced inducibility of ventricular tachyarrhythmias by 70%. TEA did not affect right ventricular-systolic pressure or contractility, although left ventricular-systolic pressure and contractility decreased modestly. Global and regional ventricular ARIs increased, including in scar and border zone regions post-TEA. TEA reduced ARI dispersion specifically in border zone regions. Ventricular effective refractory periods prolonged significantly at critical sites of arrhythmogenesis, and Smax was reduced. Interestingly, TEA significantly improved cardiac vagal function, as measured by both baroreflex sensitivity and intrinsic cardiac neural activity.

CONCLUSIONS

TEA does not compromise right ventricular function in infarcted hearts. Its antiarrhythmic mechanisms are mediated by increases in ventricular effective refractory period and ARIs, decreases in Smax, and reductions in border zone electrophysiological heterogeneities. TEA improves parasympathetic function, which may independently underlie some of its observed antiarrhythmic mechanisms. This study provides novel insights into the antiarrhythmic mechanisms of TEA while highlighting its applicability to the clinical setting.

Validation of a Demography-Based Adaptive QTc Formula using Pediatric and Adult Datasets Acquired from Humans and Guinea Pigs

Introduction

A variety of QT rate-correction (QTc) formulae have been utilized for both clinical and research purposes. However, these formulae are not universally effective, likely due to significant influences of demographic diversity on the QT-HR relationship. To address this limitation, we proposed an adaptive QTc (QTcAd) formula that adjusts to subject demographics (i.e., age). Further, we compared the efficacy and accuracy of the QTcAd formula to other widely used alternatives.

Method

Using age as a demographic parameter, we tested the QTcAd formula across diverse age groups with different heart rates (HR) in both humans and guinea pigs. Utilizing retrospective human (n=1360) and guinea pig electrocardiogram (ECG) data from in-vivo (n=55) and ex-vivo (n=66) settings, we evaluated the formula's effectiveness. Linear regression fit parameters of HR-QTc (slope and R²) were utilized for performance assessment. To evaluate the accuracy of the predicted QTc, we acquired epicardial electrical and optical voltage data from Langendorff-perfused guinea pig hearts.

Results

In both human subjects and guinea pigs, the QTcAd formula consistently outperformed other formulae across all age groups. For instance, in a 20-year-old human group (n=300), the QTcAd formula successfully nullified the inverse HR-QT relationship (R²=5.1E-09, slope=-3.5E-05), while the Bazett formula (QTcB) failed to achieve comparable effectiveness (R²= 0.20, slope=0.91). Moreover, the QTcAd formula exhibited better accuracy than the age-specific Benatar formula (QTcBe), which overcorrected QTc (1-week human QT: 263.8±14.8 ms, QTcAd: 263.8±7.3 ms, p=0.62; QTcBe: 422.5±7.3 ms, p<0.0001). The optically measured pseudo-QT interval (143±22.5 ms, n=44) was better approximated by QTcAd (180.6±17.0 ms) compared to all other formulae. Furthermore, we demonstrated that the QTcAd formula was not inferior to individual-specific QTc formulae.

Conclusion

The demography-based QTcAd formula showed superior performance across human and guinea pig age groups, which may enhance the efficacy of QTc for cardiovascular disease diagnosis, risk stratification, and drug safety testing.

What is known

Corrected QT (QTc) is a well-known ECG biomarker for cardiovascular disease risk stratification and drug safety testing. Various QT rate-correction formulae have been developed, but these formulae do not perform consistently across diverse datasets (e.g., sex, age, disease, species).

What the study adds

We introduce a novel QTc formula (QTcAd) that adapts to demographic variability, as the parameters can be modified based on the characteristics of the study population. The formula (QTcAd = QT + (|m|*(HR-HR mean )) - includes the absolute slope (m) of the linear regression of QT and heart rate (HR) and the mean HR of the population (HR mean ) as population characteristics parametersˍUsing datasets from both pediatric and adult human subjects and an animal model, we demonstrate that the QTcAd formula is more effective at eliminating the QT-HR inverse relationship, as compared to other commonly used correction formulae.

How much should we still worry about QTc prolongation in rifampicin-resistant tuberculosis? ECG findings from TB-PRACTECAL clinical trial

Regimens for the treatment of rifampicin-resistant tuberculosis currently rely on the use of QT-prolonging agents. Using data from the randomized controlled trial, TB-PRACTECAL, we investigated differences in QTcF among participants in the three interventional arms: BPaL (bedaquiline, pretomanid, and linezolid), BPaLC (BPaL with clofazimine), and BPaLM (BPaL with moxifloxacin). Additionally, we assessed whether age, body mass index, and country were causally associated with QTcF prolongation. The trial included participants from South Africa, Uzbekistan, and Belarus. A post hoc analysis of electrocardiogram data was undertaken. Random effects regression was used to model QTcF longitudinally over 24 weeks and causal frameworks guided the analysis of non-randomized independent variables. 328 participants were included in BPaL-based arms. The longitudinal analysis of investigational arms showed an initial QTcF steep increase in the first week. QTcF trajectories between weeks 2 and 24 differed slightly by regimen, with highest mean peak for BPaLC (QTcF 446.5 ms). Overall, there were 397 QTcF >450 ms (of 3,744) and only one QTcF >500 ms. The odds of QTcF >450 ms among participants in any investigational arm, was 8.33 times higher in Uzbekistan compared to Belarus (95% confidence interval: 3.25-21.33). No effect on QTcF prolongation was found for baseline age or body mass index (BMI). Clinically significant QTc prolongation was rare in this cohort of closely monitored participants. Across BPaL-based regimens, BPaLC showed a slightly longer and sustained effect on QTcF prolongation, but the differences (both in magnitude of change and trajectory over time) were clinically unimportant. The disparity in the risk of QTc prolongation across countries would be an important factor to further investigate when evaluating monitoring strategies.

CLINICAL TRIALS

This study is registered with ClinicalTrials.gov as NCT02589782.

Comparison of corrected QT (QTc) interval of electrocardiogram calculated from various formulas

QT interval in an electrocardiogram (ECG) is interpreted after correction (QTc) by various formulas. This study aimed to compare the QTcs calculated by nine formulas. Sinus rhythm ECG reports of 1140 anonymous subjects showed uncorrected QT interval of 388.49 ± 42.74 ms. The QTc calculated by Bazett (443.96 ± 57.58 ms), Fridericia (424.37 ± 50.1 ms), Dmitrienko (433.59 ± 53.37 ms), Framingham (422.59 ± 45.55 ms), Schlamowitz (433.89 ± 48.05 ms), Hodges (421.6 ± 46.4 ms), Ashman (434.33 ± 54.05 ms), Rautaharju (427.75 ± 47.4 ms), and Sarma (429.22 ± 48.67 ms) showed a significant difference F (8, 10251) = 22.78 p < 0.0001. Hence, ECG should contain the formula for proper reporting and ease of interpretation by clinicians.

Long QT Syndrome With Drugs Used in the Management of Arrhythmias: A Systematic Review

Long QT syndrome (LQTS) is a severe cardiac disorder characterized by an abnormally prolonged QTc interval on an electrocardiogram (ECG), which can result in life-threatening irregular heart rhythms. The use of certain medications, particularly anti-arrhythmic drugs such as quinidine, sotalol, and amiodarone, can lead to acquired LQTS by prolonging the QT interval through the inhibition of specific ion channels responsible for heart repolarization, which may present symptoms like fainting, seizures, and sudden cardiac arrest. This systematic review, conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 guidelines, focused on analyzing the association between Long QT syndrome and drugs utilized for managing arrhythmias, involving a thorough examination of six selected studies from an initial pool of 68 articles. It was found that antiarrhythmic drugs such as amiodarone, sotalol, dofetilide, procainamide, quinidine, and flecainide have the potential to cause QT prolongation as a side effect, which is often influenced by factors including dosage, coexisting medical conditions, electrolyte imbalances, and other risk factors. Prolonged QT interval significantly elevates the risk of a life-threatening arrhythmia called torsade de pointes. The management of this side effect typically involves reducing the medication dosage or discontinuing it altogether and, in some cases, employing selective beta blockers. However, further research is essential to improve the understanding and implementation of strategies to prevent and manage QT prolongation caused by antiarrhythmic drugs. Additional clinical studies are warranted to enhance knowledge and provide comprehensive guidelines to healthcare practitioners regarding the appropriate use of these medications. Close monitoring of the QT interval is recommended for patients receiving anti-arrhythmic therapy, and consideration should be given to patient-specific risk factors for LQTS, including age, sex, and electrolyte imbalances.

Use of new and emerging cancer drugs: what the cardiologist needs to know

The last decade has witnessed a paradigm shift in cancer therapy, from non-specific cytotoxic chemotherapies to agents targeting specific molecular mechanisms. Nonetheless, cardiovascular toxicity of cancer therapies remains an important concern. This is particularly relevant given the significant improvement in survival of solid and haematological cancers achieved in the last decades. Cardio-oncology is a subspecialty of medicine focusing on the identification and prevention of cancer therapy-related cardiovascular toxicity (CTR-CVT). This review will examine the new definition of CTR-CVT and guiding principles for baseline cardiovascular assessment and risk stratification before cancer therapy, providing take-home messages for non-specialized cardiologists.

Use of portable single-lead electrocardiogram device as an alternative for QTc monitoring in critically ill patients

PURPOSE

Acquired QT prolongation is frequent and leads to a higher mortality rate in critically ill patients. KardiaMobile 1L® (KM1L) is a portable, user-friendly single lead, mobile alternative to conventional 12-lead electrocardiogram (12-L ECG) that could be more readily available, potentially facilitating more frequent QTc assessments in intensive care units (ICU); however, there is currently no evidence to validate this potential use.

METHODS

We conducted a prospective diagnostic test study comparing QT interval measurement using KM1L with conventional 12-L ECG ordered for any reason in patients admitted to an ICU. We compared the mean difference using a paired t-test, agreement using Bland-Altman analysis, and Lin's concordance coefficient, numerical precision (proportion of QT measurements with <10 ms difference between KM1L and conventional 12-L ECG), and clinical precision (concordance for adequate discrimination of prolonged QTc).

RESULTS

We included 114 patients (61.4% men, 60% cardiovascular etiology of hospitalization) with 131 12-L ECG traces. We found no statistical difference between corrected QT measurements (427 ms vs. 428 ms, p = .308). Lin's concordance coefficient was 0.848 (95% CI 0.801-0.894, p = .001). Clinical precision was excellent in males and substantial in females (Kappa 0.837 and 0.781, respectively). Numerical precision was lower in patients with vasoactive drugs (-13.99 ms), QT-prolonging drugs (13.84 ms), antiarrhythmic drugs (-12.87 ms), and a heart rate (HR) difference of ≥5 beats per minute (bpm) between devices (-11.26 ms).

CONCLUSION

Our study validates the clinical viability of KM1L, a single-lead mobile ECG device, for identifying prolonged QT intervals in ICU patients. Caution is warranted in patients with certain medical conditions that may affect numerical precision.

Androgen Deprivation Therapy/Androgen Receptor Signaling Inhibitor Treatments for Prostate Cancer: Pathophysiology and Review of Effects on Cardiovascular Disease

Androgen deprivation therapy is the cornerstone of systemic management for prostate cancer but is associated with multiple adverse effects that must be considered during treatment. These effects occur because of the profound hypogonadism that is induced from lack of testosterone or due to the medications used in the treatment or in combination with androgen receptor signaling inhibitors. This article critically reviews the associations between androgen deprivation therapy, androgen receptor signaling inhibitors, and cardiovascular complications such as prolonged QT interval, atrial fibrillation, heart failure, atherosclerosis, coronary heart disease, venous thromboembolism, and peripheral arterial occlusive disease. These unfavorable outcomes reinforce the need for regular cardiovascular screening of patients undergoing androgen deprivation for the management of prostate cancer.

Effect on QTc interval by switching from methadone to equipotent R-methadone dose in methadone maintenance treatment patients

Methadone (R,S-methadone) can prolong the QT interval. R-methadone inhibits cardiac potassium channel function less than S-methadone. We tested if switching from methadone to R-methadone would reduce corrected QT (QTc) intervals in methadone maintenance treatment (MMT) patients. Nine patients, with automatically read QTc intervals ≥450 ms, were required to detect a 20 ms (clinically relevant) reduction in QTc intervals with 15 ms standard deviation (SD) and 90% power. Nine stabilized MMT patients, using median (range) 70 (40-120) mg methadone, were included. Data (ECG recordings, serum samples, and withdrawal symptoms) were collected both before drug intake (Cmin ) and at 3 h after drug intake (Cmax ), and were collected on the day before the switch from methadone to equipotent R-methadone dose and at 14 and 28 days after the switch. A cardiologist calculated QTc intervals retrospectively. Serum electrolytes and methadone concentrations were measured. Mean QTc intervals at Cmin were 472 ms and 422 ms on methadone (automatically and manually read) and 414 ms on R-methadone (manually read). Mean (SD) change in QTc intervals was -8 (10) ms (p = 0.047) at Cmin but non-significant at Cmax . R-methadone showed a concentration-dependent relationship with QTc intervals. Switching to R-methadone reduced QTc intervals, but far less than the 20 ms considered clinically relevant.

Relationship between Alzheimer dementia and QT interval: A meta-analysis

While the link between aging and mortality from dementia is widely appreciated, the mechanism is not clear. The objective of this study was to determine whether there is a direct relationship between Alzheimer dementia (AD) and the QT interval, because the latter has been related to cardiac mortality. A systematic review and meta-analysis were conducted after a Medline and EMBASE search using terms "Alzheimer disease or Dementia AND QT interval, QT dispersion or cardiac repolarization." Four studies with control groups were identified. There were significant differences in QT interval between individuals with AD vs individuals without dementia (controls) (odds ratio (OR)1.665 [random effects model] and 1.879 [fixed effect model]) (p < 0.001). There were significant differences in QT interval between individuals with AD vs individuals with mild cognitive impairment (MCI) (OR 1.760 [random effects] and 1.810 [fixed effect]) (p < 0.001). A significant (p <0.001) correlation exists between the QTc and the Mini-Mental State Exam (MMSE), a test of cognitive function. Two studies examined QT variability (the difference between the longest and shortest QT interval on a 12 lead ECG); the OR for QT variability AD vs MCI was 3.858 [random effects model] and 3.712 [fixed effects model] (p < 0.001). When compared to the control group, the OR for QT dispersion in AD was 6.358 [random effects model] or 5.143 ( P< 0.001) [fixed effects model]. A qualitative analysis of the data raised questions about paucity of data defining the nature of the control groups, the pathophysiologic mechanism, and the uniform use of a poor QT heart rate correction factor. The longer QT in AD, greater QT variability in AD, and the direct relationship between QT interval and AD severity supports a brain-heart connection in AD that might be fundamental to aging-induced AD and mortality. Issues with defining the control group, limited number of studies, conflicting data in population studies, and the lack of a strong electrophysiological basis underscore the need for additional research in this field.

Tolerability and safety outcomes of first-line oral second-generation antipsychotics in patients with schizophrenia

INTRODUCTION

Antipsychotics are the foundation of pharmacologic treatment for schizophrenia. There are many oral antipsychotics available and given that these medications are generally considered comparably efficacious when titrated to an adequate dose, their varied tolerability, and safety profiles become critically important for medication selection.

AREAS COVERED

This paper reviews tolerability and safety considerations for first-line second-generation oral antipsychotics currently approved for the treatment of schizophrenia in the USA. Excluded from consideration are clozapine and non-oral formulations.

EXPERT OPINION

Among antipsychotics, there are many differences in adverse reactions observed in clinical trials, such as variable likelihood to cause sedation vs insomnia, weight gain and abnormalities in glucose/lipid metabolism, hyperprolactinemia, potential for impact on the QT interval, and motoric adverse effects. Additional safety data that can help with medication selection include safety in pregnancy and lactation, and potential for drug-drug interactions. Ultimately, working with patients to personalize treatment by focusing on safety and individual tolerability considerations for various adverse effects can help in building a therapeutic alliance and improving patients' outcomes.

Engineered tissue geometry and Plakophilin-2 regulate electrophysiology of human iPSC-derived cardiomyocytes

Engineered heart tissues have been created to study cardiac biology and disease in a setting that more closely mimics in vivo heart muscle than 2D monolayer culture. Previously published studies suggest that geometrically anisotropic micro-environments are crucial for inducing "in vivo like" physiology from immature cardiomyocytes. We hypothesized that the degree of cardiomyocyte alignment and prestress within engineered tissues is regulated by tissue geometry and, subsequently, drives electrophysiological development. Thus, we studied the effects of tissue geometry on electrophysiology of micro-heart muscle arrays (μHM) engineered from human induced pluripotent stem cells (iPSCs). Elongated tissue geometries elicited cardiomyocyte shape and electrophysiology changes led to adaptations that yielded increased calcium intake during each contraction cycle. Strikingly, pharmacologic studies revealed that a threshold of prestress and/or cellular alignment is required for sodium channel function, whereas L-type calcium and rapidly rectifying potassium channels were largely insensitive to these changes. Concurrently, tissue elongation upregulated sodium channel (NaV1.5) and gap junction (Connexin 43, Cx43) protein expression. Based on these observations, we leveraged elongated μHM to study the impact of loss-of-function mutation in Plakophilin 2 (PKP2), a desmosome protein implicated in arrhythmogenic disease. Within μHM, PKP2 knockout cardiomyocytes had cellular morphology similar to what was observed in isogenic controls. However, PKP2-/- tissues exhibited lower conduction velocity and no functional sodium current. PKP2 knockout μHM exhibited geometrically linked upregulation of sodium channel but not Cx43, suggesting that post-translational mechanisms, including a lack of ion channel-gap junction communication, may underlie the lower conduction velocity observed in tissues harboring this genetic defect. Altogether, these observations demonstrate that simple, scalable micro-tissue systems can provide the physiologic stresses necessary to induce electrical remodeling of iPS-CM to enable studies on the electrophysiologic consequences of disease-associated genomic variants.

Polypharmacy and Reversible Drug Induced QT Prolongation in a Patient with Advanced Cancer: Case Report

QT prolongation is related to the development of ventricular arrhythmias such as Torsade de Pointes (TdP) that can lead to sudden cardiac death. Several drugs used in the treatment of patients with advanced cancer may induce QT prolongation due to their interference with cardiac ion channels. Some patients may be at higher risk if predisposing factors are present. Herein we present the case of a patient with advanced cancer under anti-tumor treatment with radical intention that developed a reversible drug-induced QT prolongation when simultaneously treated with methadone, haloperidol and fluoxetine that presented with chest pain and bradycardia. An approach to cancer patients at risk for drug-induced QT prolongation is discussed highlighting the need of a thorough medication review with a special focus in the patient with polypharmacy.

QTc intervals at rest and during exercise assessed by group correction formulas in survivors of childhood acute lymphoblastic leukemia

INTRODUCTION

Early signs of subclinical cardiac damage must be identified before they turn into clinical manifestations. Tailoring a formula is relevant for precise QTc evaluation in childhood acute lymphoblastic leukemia (ALL) survivors considering they are at risk of long-term cardiac problems. Therefore, we aim to develop group heart rate correction formulas for QT intervals in childhood ALL survivors at rest and during exercise, and to assess the applicability of these methods across a variety of risk groups exposed to diverse chemotherapy dosages.

METHODS

Two hundred and fifty childhood ALL survivors in the PETALE study were classified into 3 groups depending on their prognostic risk group. ECG measurements (QT and RR intervals) were made at rest and during a cardiopulmonary exercise test. QT correction for heart rate was applied using 5 different formulas, which included 2 previously published formulas and 3 group-specific formulas for each sex.

RESULTS

The QT/RR relation showed 2 different curves between rest and during exercise, which was worse for females. Group-specific QTc formulas allowed adequate heart rate-corrected QT interval, independently of the cumulative dose of doxorubicin received during treatment. Group-specific formulas showed significantly shorter QTc intervals than QTc from Bazett's formula. QTc (Bazett's formula) values surpassed the established clinical norm in 22 males (11%) and 22 females (11%), with a majority occurring during exercise, affecting 15 males (7.5%) and 10 females (5%).

CONCLUSION

This study shows the applicability of personalized group correction of QT/RR data in childhood ALL survivors. Our comprehensive assessments (spanning rest, exercise, and recovery) is an effective approach for risk stratification of cardiac complications in childhood ALL survivors.

Genetic risk factors for drug-induced long QT syndrome: findings from a large real-world case-control study

Aim: Drug-induced long QT syndrome (diLQTS), an adverse effect of many drugs, can lead to sudden cardiac death. Candidate genetic variants in cardiac ion channels have been associated with diLQTS, but several limitations of previous studies hamper clinical utility. Materials & methods: Thus, the purpose of this study was to assess the associations of KCNE1-D85N, KCNE2-I57T and SCN5A-G615E with diLQTS in a large observational case-control study (6,083 self-reported white patients treated with 27 different high-risk QT-prolonging medications; 12.0% with diLQTS). Results: KCNE1-D85N significantly associated with diLQTS (adjusted odds ratio: 2.24 [95% CI: 1.35-3.58]; p = 0.001). Given low minor allele frequencies, the study had insufficient power to analyze KCNE2-I57T and SCN5A-G615E. Conclusion: KCNE1-D85N is a risk factor for diLQTS that should be considered in future clinical practice guidelines.

Evaluating Monitoring Guidelines of Clozapine-Induced Adverse Effects: a Systematic Review

BACKGROUND AND OBJECTIVES

Despite the evidence that no other antipsychotic is effective as clozapine for the treatment of resistant schizophrenia, it is associated with various metabolic, neuroendocrine, cardiovascular, and gastrointestinal adverse effects. Guidelines aiming to address the monitoring of clozapine's (serious) adverse effects can be helpful to prevent and treat these effects. However, many of these guidelines seem to lack one or more important monitoring recommendations. We aimed to systematically review the content and quality of existing monitoring guidelines/recommendations for clozapine-induced adverse effects.

METHODS

A comprehensive and systematic literature search, using the MEDLINE, Embase, Web of Science, and Cochrane databases, was conducted for guidelines/recommendations on the monitoring of clozapine-induced adverse events, published between January 2004 and April 2023 (last search 16 April 2023). Only peer-reviewed published guidelines reporting on the comprehensive monitoring of all major clozapine-induced adverse effects and including evidence-based recommendations, developed after the year 2004, were included. Studies reporting on the monitoring of adverse effects of clozapine without being a formal guideline, guidelines reporting on the monitoring of one or a limited number of adverse effects of clozapine, guidelines that were not peer reviewed or published, expert opinion papers without formal consensus guideline development, or guidelines developed before the year 2004, were excluded. The Appraisal of Guidelines for Research and Evaluation II (AGREE-II) tool was used to evaluate the guidelines/recommendations' quality.

RESULTS

Only one guideline met the inclusion criteria. This consensus statement made recommendations for hematological monitoring, and the monitoring of metabolic, cardiac, and three other adverse effects. Highest scores for the qualitative assessment were found for the domains "scope and purpose" (66.7%), "clarity of presentation" (44.4%), and "editorial independence" (66.7%). Lowest scores were found for "rigor of development" (14.6%) and "applicability" (0%).

CONCLUSIONS

Future guidelines should develop more comprehensive recommendations about specific clozapine-induced adverse effects, including constipation, myocarditis, tachycardia, and seizures, as well as include a rechallenge policy. There is an urgent need for well-developed, methodologically stringent, guidelines.

REGISTRATION

PROSPERO registration number, CRD42023402480.

Exploring the Connection Between Relaxed Myosin States and the Anrep Effect

The Anrep effect is an adaptive response that increases left ventricular contractility following an acute rise in afterload. Although the mechanistic origin remains undefined, recent findings suggest a two-phase activation of resting myosin for contraction, involving strain-sensitive and posttranslational phases. We propose that this mobilization represents a transition among the relaxed states of myosin-specifically, from the super-relaxed (SRX) to the disordered-relaxed (DRX)-with DRX myosin ready to participate in force generation. This hypothesis offers a unified explanation that connects myosin's SRX-DRX equilibrium and the Anrep effect as parts of a singular phenomenon. We underscore the significance of this equilibrium in modulating contractility, primarily studied in the context of hypertrophic cardiomyopathy, the most common inherited cardiomyopathy associated with diastolic dysfunction, hypercontractility, and left ventricular hypertrophy. As we posit that the cellular basis of the Anrep effect relies on a two-phased transition of myosin from the SRX to the contraction-ready DRX configuration, any dysregulation in this equilibrium may result in the pathological manifestation of the Anrep phenomenon. For instance, in hypertrophic cardiomyopathy, hypercontractility is linked to a considerable shift of myosin to the DRX state, implying a persistent activation of the Anrep effect. These valuable insights call for additional research to uncover a clinical Anrep fingerprint in pathological states. Here, we demonstrate through noninvasive echocardiographic pressure-volume measurements that this fingerprint is evident in 12 patients with hypertrophic obstructive cardiomyopathy before septal myocardial ablation. This unique signature is characterized by enhanced contractility, indicated by a leftward shift and steepening of the end-systolic pressure-volume relationship, and a prolonged systolic ejection time adjusted for heart rate, which reverses post-procedure. The clinical application of this concept has potential implications beyond hypertrophic cardiomyopathy, extending to other genetic cardiomyopathies and even noncongenital heart diseases with complex etiologies across a broad spectrum of left ventricular ejection fractions.

QTc Prolongation to Predict Mortality in Patients Admitted with COVID-19 Infection: An Observational Study

BACKGROUND

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) causes Coronavirus disease 2019 (COVID-19), characterized by pulmonary infection ranging from asymptomatic forms to respiratory insufficiency and death. Evidence of cardiac involvement in COVID-19 is increasing, and systemic inflammation or direct heart damage by SARS-CoV-2 can prolong the corrected QT interval (QTc).

METHODS

In this observational study, a total of 333 consecutive patients admitted to the Covid Center of Verona University Hospital from November 2020 to April 2021 were included. Patients with bundle branch block, pacemaker-controlled heart rhythm and heart rate >120 beats/min were excluded. A complete electrocardiogram (ECG) was performed at admission, and QTc values of ≥440 ms for males and ≥460 ms for females were considered prolonged.

RESULTS

Overall, 153 patients had prolonged QTc (45.5%). In multivariate logistic regression analysis, male sex (odds ratio (OR)=6.612, p=0.046), troponin (OR=1.04, p=0.015) and lymphocyte count (OR=3.047, p=0.019) were independently associated with QTc prolongation. Multivariate logistic regression showed that QTc was independently associated with mortality (OR=4.598, p=0.036). Age, sex, the ratio between the partial pressure of oxygen (PaO2) and the fraction of inspired oxygen (FiO2) (P/F), and fibrosis-4 index for liver fibrosis (FIB-4) were also independently associated with mortality.

CONCLUSION

QTc interval prolongation appears to be a frequent finding in patients with COVID-19. Moreover, prolonged QTc may be predictive of more severe forms of COVID-19 and worse outcome.

Comparison of QTc interval changes in drug-resistant tuberculosis patients on delamanid-containing regimens versus shorter treatment regimens

BACKGROUND

Delamanid (DLM) is a relatively new drug for drug-resistant tuberculosis (DR-TB) that has been used in Indonesia since 2019 despite its limited safety data. DLM is known to inhibit hERG potassium channel with the potential to cause QT prolongation which eventually leads to Torsades de pointes (TdP).

OBJECTIVE

This study aims to analyse the changes of QTc interval in DR-TB patients on DLM regimen compared to shorter treatment regimens (STR).

METHODS

A retrospective cohort was implemented on secondary data obtained from two participating hospitals. The QTc interval and the changes in QTc interval from baseline (ΔQTc) were assessed every 4 weeks for 24 weeks.

RESULTS

The maximum increased of QTc interval and ΔQTc interval were smaller in the DLM group with mean difference of 18,6 (95%CI 0.3 to 37.5) and 31.6 milliseconds (95%CI 14.1 to 49.1) respectively. The proportion of QTc interval prolongation in DLM group were smaller than STR group (RR=0.62; 95%CI 0.42 to 0.93).

CONCLUSION

This study has shown that DLM regimens are less likely to increase QTc interval compared to STR. However, close monitoring of the risk of QT interval prolongation needs to be carried out upon the use of QT interval prolonging antituberculoid drugs.

Residential greenness alleviated the adverse associations of long-term exposure to ambient PM1 with cardiac conduction abnormalities in rural adults

BACKGROUND

Ambient air pollution was linked to elevated risks of adverse cardiovascular events, and alterations in electrophysiological properties of the heart might be potential pathways. However, there is still lacking research exploring the associations between PM1 exposure and cardiac conduction parameters. Additionally, the interactive effects of PM1 and residential greenness on cardiac conduction parameters in resource-limited areas remain unknown.

METHODS

A total of 27483 individuals were enrolled from the Henan Rural Cohort study. Cardiac conduction parameters were tested by 12-lead electrocardiograms. Concentrations of PM1 were evaluated by satellite-based spatiotemporal models. Levels of residential greenness were assessed using Enhanced Vegetation Index (EVI) and Normalized difference vegetation index (NDVI). Logistic regression models and restricted cubic splines were fitted to explore the associations of PM1 and residential greenness exposure with cardiac conduction abnormalities risk, and the interaction plot method was performed to visualize their interaction effects.

RESULTS

The 3-year median concentration of PM1 was 56.47 (2.55) μg/m3, the adjusted odds rate (ORs) and 95% confidence intervals (CIs) for abnormal HR, PR, QRS, and QTc interval risk in response to 1 μg/m3 increase in PM1 were 1.064 (1.044, 1.085), 1.037 (1.002, 1.074), 1.061 (1.044, 1.077) and 1.046 (1.028, 1.065), respectively. Participants exposure to higher levels of PM1 had increased risks of abnormal HR (OR = 1.221, 95%CI: 1.144, 1.303), PR (OR = 1.061, 95%CI: 0.940, 1.196), QRS (OR = 1.225, 95%CI: 1.161, 1.294) and QTc interval (OR = 1.193, 95%CI: 1.121, 1.271) compared with lower levels of PM1. Negative interactive effects of exposure to PM1 and residential greenness on abnormal HR, QRS, and QTc intervals were observed (Pfor interaction < 0.05).

CONCLUSION

Long-term PM1 exposure was associated with elevated cardiac conduction abnormalities risks, and this adverse association might be mitigated by residential greenness to some extent. These findings emphasize that controlling PM1 pollution and increasing greenness levels might be effective strategies to reduce cardiovascular disease burdens in resource-limited areas.

The optimal QTc selection in patients of acute myocardial infarction with poor perioperative prognosis

BACKGROUND

The predictive utility of QTc values, calculated through various correction formulas for the incidence of postoperative major adverse cardiovascular and cerebrovascular events (MACCE) in patients experiencing acute myocardial infarction (AMI), warrants further exploration. This study endeavors to ascertain the predictive accuracy of disparate QTc values for MACCE occurrences in patients with perioperative AMI.

METHODS

A retrospective cohort of three hundred fourteen AMI patients, comprising 81 instances of in-hospital MACCE and 233 controls, was assembled, with comprehensive collection of baseline demographic and clinical data. QTc values were derived employing the correction formulas of Bazett, Fridericia, Hodges, Ashman, Framingham, Schlamowitz, Dmitrienko, Rautaharju, and Sarma. Analytical methods encompassed comparative statistics, Spearman correlation analysis, binary logistic regression models, receiver operating characteristic (ROC) curves, and decision curve analysis (DCA).

RESULTS

QTc values were significantly elevated in the MACCE cohort compared to controls (P < 0.05). Spearman's correlation analysis between heart rate and QTc revealed a modest positive correlation for the Sarma formula (QTcBaz) (ρ = 0.46, P < 0.001). Within the multifactorial binary logistic regression, each QTc variant emerged as an independent risk factor for MACCE, with the Sarma formula-derived QTc (QTcSar) presenting the highest hazard ratio (OR = 1.025). ROC curve analysis identified QTcSar with a threshold of 446 ms as yielding the superior predictive capacity (AUC = 0.734), demonstrating a sensitivity of 60.5% and a specificity of 82.8%. DCA indicated positive net benefits for QTcSar at high-risk thresholds ranging from 0 to 0.66 and 0.71-0.96, with QTcBaz, prevalent in clinical settings, showing positive net benefits at thresholds extending to 0-0.99.

CONCLUSION

For perioperative AMI patients, QTcSar proves more advantageous in monitoring QTc intervals compared to alternative QT correction formulas, offering enhanced predictive prowess for subsequent MACCE incidents.

Risk assessment of post-myocardial infarction patients with preserved ejection fraction using 45-min short resting Holter electrocardiographic recordings

BACKGROUND

Risk stratification for sudden cardiac death in post-myocardial infarction (post-MI) patients remains a challenging task. Several electrocardiographic noninvasive risk factors (NIRFs) have been associated with adverse outcomes and were used to refine risk assessment. This study aimed to evaluate the performance of NIRFs extracted from 45-min short resting Holter ECG recordings (SHR), in predicting ventricular tachycardia inducibility with programmed ventricular stimulation (PVS) in post-MI patients with preserved left ventricular ejection fraction (LVEF).

METHODS

We studied 99 post-MI ischemia-free patients (mean age: 60.5 ± 9.5 years, 86.9% men) with LVEF ≥40%, at least 40 days after revascularization. All the patients underwent PVS and a high-resolution SHR. The following parameters were evaluated: mean heart rate, ventricular arrhythmias (premature ventricular complexes, couplets, tachycardias), QTc duration, heart rate variability (HRV), deceleration capacity, heart rate turbulence, late potentials, and T-wave alternans.

RESULTS

PVS was positive in 24 patients (24.2%). HRV, assessed by the standard deviation of normal-to-normal R-R intervals (SDNN), was significantly decreased in the positive PVS group (42 ms vs. 51 ms, p = .039). SDNN values <50 ms were also associated with PVS inducibility (OR 3.081, p = .032 in univariate analysis, and 4.588, p = .013 in multivariate analysis). No significant differences were identified for the other NIRFs. The presence of diabetes, history of ST-elevation MI (STEMI) and LVEF <50% were also important predictors of positive PVS.

CONCLUSIONS

HRV assessed from SHR, combined with other noninvasive clinical and echocardiographic variables (diabetes, STEMI history, LVEF), can provide an initial, practical, and rapid screening tool for arrhythmic risk assessment in post-MI patients with preserved LVEF.

Provocation testing in congenital long QT syndrome: A practical guide

Congenital long QT syndrome (LQTS) is a hereditary cardiac channelopathy with an estimated prevalence of 1 in 2500. A prolonged resting QT interval corrected for heart rate (QTc interval) remains a key diagnostic component; however, the QTc value may be normal in up to 40% of patients with genotype-positive LQTS and borderline in a further 30%. Provocation of QTc prolongation and T-wave changes may be pivotal to unmasking the diagnosis and useful in predicting genotype. LQTS provocation testing involves assessment of repolarization during and after exercise, in response to changes in heart rate or autonomic tone, with patients with LQTS exhibiting a maladaptive repolarization response. We review the utility and strengths and limitations of 4 forms of provocation testing-stand-up test, exercise stress test, epinephrine challenge, and mental stress test-in diagnosing LQTS and provide some practical guidance for performing provocation testing. Ultimately, exercise testing, when feasible, is the most useful form of provocation testing when considering diagnostic sensitivity and specificity.

Tools to differentiate between Filamin C and Titin truncating variant carriers: value of MRI

Whereas truncating variants of the giant protein Titin (TTNtv) are the main cause of familial dilated cardiomyopathy (DCM), recently Filamin C truncating variants (FLNCtv) were identified as a cause of arrhythmogenic cardiomyopathy (ACM). Our aim was to characterize and compare clinical and MRI features of TTNtv and FLNCtv in the Belgian population. In index patients referred for genetic testing of ACM/DCM, FLNCtv and TTNtv were found in 17 (3.6%) and 33 (12.3%) subjects, respectively. Further family cascade screening yielded 24 and 19 additional truncating variant carriers in FLNC and TTN, respectively. The main phenotype was ACM in FLNCtv carriers whereas TTNtv carriers showed either an ACM or DCM phenotype. Non-sustained Ventricular Tachycardia was frequent in both populations. MRI data, available in 28/40 FLNCtv and 32/52 TTNtv patients, showed lower Left Ventricular (LV) ejection fraction and lower LV strain in TTNtv patients (p < 0.01). Conversely, both the frequency (68% vs 22%) and extent of non-ischemic myocardial late gadolinium enhancement (LGE) was significantly higher in FLNCtv patients (p < 0.01). Hereby, ring-like LGE was found in 16/19 (84%) FLNCtv versus 1/7 (14%) of TTNtv patients (p < 0.01). In conclusion, a large number of FLNCtv and TTNtv patients present with an ACM phenotype but can be separated by cardiac MRI. Whereas FLNCtv patients often have extensive myocardial fibrosis, typically following a ring-like pattern, LV dysfunction without or limited replacement fibrosis is the common TTNtv phenotype.

Proarrhythmic changes in human cardiomyocytes during hypothermia by milrinone and isoprenaline, but not levosimendan: an experimental in vitro study

BACKGROUND

Accidental hypothermia, recognized by core temperature below 35 °C, is a lethal condition with a mortality rate up to 25%. Hypothermia-induced cardiac dysfunction causing increased total peripheral resistance and reduced cardiac output contributes to the high mortality rate in this patient group. Recent studies, in vivo and in vitro, have suggested levosimendan, milrinone and isoprenaline as inotropic treatment strategies in this patient group. However, these drugs may pose increased risk of ventricular arrhythmias during hypothermia. Our aim was therefore to describe the effects of levosimendan, milrinone and isoprenaline on the action potential in human cardiomyocytes during hypothermia.

METHODS

Using an experimental in vitro-design, levosimendan, milrinone and isoprenaline were incubated with iCell2 hiPSC-derived cardiomyocytes and cellular action potential waveforms and contraction were recorded from monolayers of cultured cells. Experiments were conducted at temperatures from 37 °C down to 26 °C. One-way repeated measures ANOVA was performed to evaluate differences from baseline recordings and one-way ANOVA was performed to evaluate differences between drugs, untreated control and between drug concentrations at the specific temperatures.

RESULTS

Milrinone and isoprenaline both significantly increases action potential triangulation during hypothermia, and thereby the risk of ventricular arrhythmias. Levosimendan, however, does not increase triangulation and the contractile properties also remain preserved during hypothermia down to 26 °C.

CONCLUSIONS

Levosimendan remains a promising candidate drug for inotropic treatment of hypothermic patients as it possesses ability to treat hypothermia-induced cardiac dysfunction and no increased risk of ventricular arrhythmias is detected. Milrinone and isoprenaline, on the other hand, appears more dangerous in the hypothermic setting.

Dose-dependent QTc interval prolongation under haloperidol and pipamperone in the management of delirium in a naturalistic setting

Objective

Delirium is an acute, life-threatening neuropsychiatric disorder frequently occurring among hospitalized patients. Antipsychotic medications are often recommended for delirium management but are associated with cardiovascular risks. This study aimed to investigate the frequency and magnitude of QTc interval prolongation and clinically relevant side effects occurring in delirium patients managed with haloperidol and/or pipamperone.

Methods

This descriptive retrospective cohort study evaluated 102 elderly (mean age: 73.2 years) inpatients with delirium treated with either haloperidol, pipamperone, a combination of both, or neither in a naturalistic setting over the course of up to 20 days or until the end of delirium.

Results

A total of 86.3% of patients were treated with haloperidol and/or pipamperone at a mean daily haloperidol-equipotent dose of 1.2 ± 1 mg. Non-cardiovascular side effects were registered in 2.9% of all patients and correlated with higher scores on the Delirium Observation Screening Scale. They did not occur more frequently under antipsychotic treatment. The frequency of QTc interval prolongation was comparably common among all groups, but prolongation magnitude was higher under antipsychotic treatment. It was positively correlated with antipsychotic dosage and the total number of QTc interval-prolonging substances administered. Critical QTc interval prolongation was registered in 21.6% (n = 19) of patients in the group treated with antipsychotics compared to 14.3% (n = 2) of patients in the unmedicated group; however, the difference was not statistically significant. Polypharmacy was associated with a higher risk of critical QTc interval prolongation and increased mortality during delirium.

Conclusion

Delirium treatment with haloperidol and/or pipamperone was not associated with a higher risk of QTc-interval prolongation in this naturalistic patient sample but was greater in magnitude and correlated with equipotent dosage and the number of QT interval-prolonging substances used. Polypharmacy was associated with higher mortality and increased risk of critical QTc prolongation.

Corrected QTc interval combined with troponin value and mortality in acute ischemic stroke

Background and Purpose

Cardiac biomarkers including, elevated troponin (ET) and prolonged heart rate-corrected QT (PQTc) interval on electrocardiography are known to frequent and have a prognostic significance in patients with acute ischemic stroke (AIS). However, it is still challenging to practically apply the results for appropriate risk stratification. This study evaluate whether combining ET and PQTc interval can better assess the long-term prognosis in AIS patients.

Methods

In this prospectively registered observational study between May 2007 and December 2011, ET was defined as serum troponin-I ≥ 0.04 ng/ml and PQTc interval was defined as the highest tertile of sex-specific QTc interval (men ≥ 469 ms or women ≥ 487 ms).

Results

Among the 1,668 patients [1018 (61.0%) men; mean age 66.0 ± 12.4 years], patients were stratified into four groups according to the combination of ET and PQTc intervals. During a median follow-up of 33 months, ET (hazard ratio [HR]: 4.38, 95% confidence interval [CI]: 2.94-6.53) or PQTc interval (HR: 1.53, 95% CI: 1.16-2.01) alone or both (HR: 1.77, 95% CI: 1.16-2.71) was associated with increased all-cause mortality. Furthermore, ET, PQTc interval alone or both was associated with vascular death, whereas only ET alone was associated with non-vascular death. Comorbidity burden, especially atrial fibrillation and congestive heart failure, and stroke severity gradually increased both with troponin value and QTc-interval.

Conclusions

In patients with AIS, combining ET and PQTc interval on ECG enhances risk stratification for long-term mortality while facilitating the discerning ability for the burden of comorbidities and stroke severity.

Domain randomization using synthetic electrocardiograms for training neural networks

We present a method for training neural networks with synthetic electrocardiograms that mimic signals produced by a wearable single lead electrocardiogram monitor. We use domain randomization where the synthetic signal properties such as the waveform shape, RR-intervals and noise are varied for every training example. Models trained with synthetic data are compared to their counterparts trained with real data. Detection of r-waves in electrocardiograms recorded during different physical activities and in atrial fibrillation is used to assess the performance. By allowing the randomization of the synthetic signals to increase beyond what is typically observed in the real-world data the performance is on par or superseding the performance of networks trained with real data. Experiments show robust model performance using different seeds and on different unseen test sets that were fully separated from the training phase. The ability of the model to generalize well to hidden test sets without any specific tuning provides a simple and explainable alternative to more complex adversarial domain adaptation methods for model generalization. This method opens up the possibility of extending the use of synthetic data towards domain insensitive cardiac disease classification when disease specific a priori information is used in the electrocardiogram generation. Additionally, the method provides training with free-to-collect data with accurate labels, control of the data distribution eliminating class imbalances that are typically observed in health-related data, and the generated data is inherently private.

Modeling time-delayed concentration-QT effects with ACT-1014-6470, a novel oral complement factor 5a receptor 1 (C5a1 receptor) antagonist

The novel oral complement factor 5a receptor 1 antagonist ACT-1014-6470 was well tolerated in single- and multiple-ascending dose studies, including 24 h Holter electrocardiogram (ECG) recordings evaluating its cardiodynamics based on data from single doses of 30-200 mg and twice-daily (b.i.d.) dosing of 30-120 mg for 4.5 days. By-time point, categorical, and morphological analyses as well as concentration-QT modeling and simulations were performed. No relevant effect of ACT-1014-6470 on ECG parameters was observed in the categorical and morphological analyses. After single-dose administration, the by-time point analysis indicated a delayed dose-dependent increase in placebo-corrected change from baseline in QT interval corrected with Fridericia's formula (ΔΔQTcF) at >6 h postdose. After b.i.d. dosing, ΔΔQTcF remained elevated during the 24-h recording period, suggesting that the effect was not directly related to ACT-1014-6470 plasma concentration. The concentration-QT model described change from baseline in QTcF (ΔQTcF)-time profiles best with a 1-oscillator model of 24 h for circadian rhythm, an effect compartment, and a sigmoidal maximum effect model. Model-predicted ΔΔQTcF was derived for lower doses and less-frequent dosing than assessed clinically. Median and 90% prediction intervals of ΔΔQTcF for once-daily doses of 30 mg and b.i.d. doses of 10 mg did not exceed the regulatory threshold of 10 ms but would achieve ACT-1014-6470 plasma concentrations enabling adequate target engagement. Results from cardiodynamic assessments identified dose levels and dosing regimens that could be considered for future clinical trials, attempting to reduce QT liability.

Screening for Rare Coding Variants That Associate With the QTc Interval in Iceland

Background Long-QT syndrome (LQTS) is a cardiac repolarization abnormality that can lead to sudden cardiac death. The most common causes are rare coding variants in the genes KCNQ1, KCNH2, and SCN5A. The data on LQTS epidemiology are limited, and information on expressivity and penetrance of pathogenic variants is sparse. Methods and Results We screened for rare coding variants associated with the corrected QT (QTc) interval in Iceland. We explored the frequency of the identified variants, their penetrance, and their association with severe events. Twelve variants were associated with the QTc interval. Five in KCNQ1, 3 in KCNH2, 2 in cardiomyopathy genes MYBPC3 and PKP2, and 2 in genes where coding variants have not been associated with the QTc interval, ISOC1 and MYOM2. The combined carrier frequency of the 8 variants in the previously known LQTS genes was 530 per 100 000 individuals (1:190). p.Tyr315Cys and p.Leu273Phe in KCNQ1 were associated with having a mean QTc interval longer than 500 ms (P=4.2×10^-7; odds ratio [OR], 38.6; P=8.4×10^-10, OR, 26.5; respectively), and p.Leu273Phe was associated with sudden cardiac death (P=0.0034; OR, 2.99). p.Val215Met in KCNQ1 was carried by 1 in 280 Icelanders, had a smaller effect on the QTc interval (P=1.8×10^-44; effect, 22.8 ms), and did not associate with severe clinical events. Conclusions The carrier frequency of associating variants in LQTS genes was higher than previous estimates of the prevalence of LQTS. The variants have variable effects on the QTc interval, and carriers of p.Tyr315Cys and p.Leu273Phe have a more severe disease than carriers of p.Val215Met. These data could lead to improved identification, risk stratification, and a more precise clinical approach to those with QTc prolongation.

Electrocardiographic parameters and the risk of new-onset atrial fibrillation in the general population: the Rotterdam Study

AIMS

We aimed to assess the (shape of the) association and sex differences in the link between electrocardiographic parameters and new-onset atrial fibrillation (AF).

METHODS AND RESULTS

A total of 12 212 participants free of AF at baseline from the population-based Rotterdam Study were included. Up to five repeated measurements of electrocardiographic parameters including PR, QRS, QT, QT corrected for heart rate (QTc), JT, RR interval, and heart rate were assessed at baseline and follow-up examinations. Cox proportional hazards- and joint models, adjusted for cardiovascular risk factors, were used to determine the (shape of the) association between baseline and longitudinal electrocardiographic parameters with new-onset AF. Additionally, we evaluated potential sex differences. During a median follow-up of 9.3 years, 1282 incident AF cases occurred among 12 212 participants (mean age 64.9 years, 58.2% women). Penalized cubic splines revealed that associations between baseline electrocardiographic measures and risk of new-onset AF were generally U- and N-shaped. Sex differences in terms of the shape of the various associations were most apparent for baseline PR, QT, QTc, RR interval, and heart rate in relation to new-onset AF. Longitudinal measures of higher PR interval [fully adjusted hazard ratio (HR), 95% confidence interval (CI), 1.43, 1.02-2.04, P = 0.0393] and higher QTc interval (fully adjusted HR, 95% CI, 5.23, 2.18-12.45, P = 0.0002) were significantly associated with new-onset AF, in particular in men.

CONCLUSION

Associations of baseline electrocardiographic measures and risk of new-onset AF were mostly U- and N-shaped. Longitudinal electrocardiographic measures of PR and QTc interval were significantly associated with new-onset AF, in particular among men.

Ventricular Arrhythmia in Cancer Patients: Mechanisms, Treatment Strategies and Future Avenues

Cardiovascular disease and cancer are the leading causes of morbidity and mortality in the US. Despite the significant progress made in cancer treatment leading to improved prognosis and survival, ventricular arrhythmias (VA) remain a known cardiovascular complication either exacerbated or induced by the direct and indirect effects of both traditional and novel cancer treatments. Although interruption of cancer treatment because of VA is rarely required, knowledge surrounding this issue is essential for optimising the overall care of patients with cancer. The mechanisms of cancer-therapeutic-induced VA are poorly understood. This review will discuss the ventricular conduction (QRS) and repolarisation abnormalities (QTc prolongation), and VAs associated with cancer therapies, as well as existing strategies for the identification, prevention and management of cancer-treatment-induced VAs.

Individualized QT interval (QTi) is a powerful diagnostic tool in long QT syndrome: results from a large validation study

Aims

Diagnosis of Long QT syndrome (LQTS) is based on prolongation of the QT interval corrected for heart rate (QTc) on surface ECG and genotyping. However, up to 25% of genotype positive patients have a normal QTc interval. We recently showed that individualized QT interval (QTi) derived from 24 h holter data and defined as the QT value at the intersection of an RR interval of 1,000 ms with the linear regression line fitted through QT-RR data points of each individual patient was superior over QTc to predict mutation status in LQTS families. This study aimed to confirm the diagnostic value of QTi, fine-tune its cut-off value and evaluate intra-individual variability in patients with LQTS.

Methods

From the Telemetric and Holter ECG Warehouse, 201 recordings from control individuals and 393 recordings from 254 LQTS patients were analysed. Cut-off values were obtained from ROC curves and validated against an in house LQTS and control cohort.

Results

ROC curves indicated very good discrimination between controls and LQTS patients with QTi, both in females (AUC 0.96) and males (AUC 0.97). Using a gender dependent cut-off of 445 ms in females and 430 ms in males, a sensitivity of 88% and specificity of 96% were achieved, which was confirmed in the validation cohort. No significant intra-individual variability in QTi was observed in 76 LQTS patients for whom at least two holter recordings were available (483 ± 36 ms vs. 489 ± 42 ms, p = 0.11).

Conclusions

This study confirms our initial findings and supports the use of QTi in the evaluation of LQTS families. Using the novel gender dependent cut-off values, a high diagnostic accuracy was achieved.

Cardiovascular Safety of Hydroxychloroquine-Azithromycin in 424 COVID-19 Patients

Background and Objectives: Hydroxychloroquine (HCQ) combined with azithromycin (AZM) has been widely administered to patients with COVID-19 despite scientific controversies. In particular, the potential of prolong cardiac repolarization when using this combination has been discussed. Materials and Methods: We report a pragmatic and simple safety approach which we implemented among the first patients treated for COVID-19 in our center in early 2020. Treatment contraindications were the presence of severe structural or electrical heart disease, baseline corrected QT interval (QTc) > 500 ms, hypokalemia, or other drugs prolonging QTc that could not be interrupted. Electrocardiogram and QTc was evaluated at admission and re-evaluated after 48 h of the initial prescription. Results: Among the 424 consecutive adult patients (mean age 46.3 ± 16.1 years; 216 women), 21.5% patients were followed in conventional wards and 78.5% in a day-care unit. A total of 11 patients (2.6%) had contraindications to the HCQ-AZ combination. In the remaining 413 treated patients, there were no arrhythmic events in any patient during the 10-day treatment regimen. QTc was slightly but statistically significantly prolonged by 3.75 ± 25.4 ms after 2 days of treatment (p = 0.003). QTc prolongation was particularly observed in female outpatients <65 years old without cardiovascular disease. Ten patients (2.4%) developed QTc prolongation > 60 ms, and none had QTc > 500 ms. Conclusions: This report does not aim to contribute to knowledge of the efficacy of treating COVID-19 with HCQ-AZ. However, it shows that a simple initial assessment of patient medical history, electrocardiogram (ECG), and kalemia identifies contraindicated patients and enables the safe treatment of COVID-19 patients with HCQ-AZ. QT-prolonging anti-infective drugs can be used safely in acute life-threatening infections, provided that a strict protocol and close collaboration between infectious disease specialists and rhythmologists are applied.

Added value of patient- and drug-related factors to stratify drug-drug interaction alerts for risk of QT prolongation: Development and validation of a risk prediction model

AIMS

Many clinical decision support systems trigger warning alerts for drug-drug interactions potentially leading to QT prolongation and torsades de pointes (QT-DDIs). Unfortunately, there is overalerting and underalerting because stratification is only based on a fixed QT-DDI severity level. We aimed to improve QT-DDI alerting by developing and validating a risk prediction model considering patient- and drug-related factors.

METHODS

We fitted 31 predictor candidates to a stepwise linear regression for 1000 bootstrap samples and selected the predictors present in 95% of the 1000 models. A final linear regression model with those variables was fitted on the original development sample (350 QT-DDIs). This model was validated on an external dataset (143 QT-DDIs). Both true QTc and predicted QTc were stratified into three risk levels (low, moderate and high). Stratification of QT-DDIs could be appropriate (predicted risk = true risk), acceptable (one risk level difference) or inappropriate (two risk levels difference).

RESULTS

The final model included 11 predictors with the three most important being use of antiarrhythmics, age and baseline QTc. Comparing current practice to the prediction model, appropriate stratification increased significantly from 37% to 54% appropriate QT-DDIs (increase of 17.5% on average [95% CI +5.4% to +29.6%], p_adj  = 0.006) and inappropriate stratification decreased significantly from 13% to 1% inappropriate QT-DDIs (decrease of 11.2% on average [95% CI -17.7% to -4.7%], p_adj  ≤ 0.001).

CONCLUSION

The prediction model including patient- and drug-related factors outperformed QT alerting based on QT-DDI severity alone and therefore is a promising strategy to improve DDI alerting.

Comparison of different QT correction methods for nonclinical safety assessment in ketamine-anesthetized Indian rhesus monkeys (Macaca mulatta)

Rhesus monkeys are a non-rodent species employed in the preclinical safety evaluation of pharmaceuticals and biologics. These nonhuman primate species have been increasingly used in biomedical research because of the similarity in their ionic mechanisms of repolarization with humans. Heart rate and QT interval are two primary endpoints in determining the pro-arrhythmic risk of drugs. As heart rate and QT interval have an inverse relationship, any change in heart rate causes a subsequent change in QT interval. This warrants for calculation of a corrected QT interval. This study aimed to identify an appropriate formula that best corrected QT for change in heart rate. We employed seven formulas based on source-species type, clinical relevance, and requirements of various international regulatory guidelines. Data showed that corrected QT interval values varied drastically for different correction formulas. Equations were compared on their slope values based on QTc versus RR plots. The rank order of the slope for different formulas was (closest to farthest from zero) QTcNAK, QTcHAS, QTcBZT, QTcFRD, QTcVDW, QTcHDG, and QTcFRM. QTcNAK emerged to be the best correcting formula in this study. It showed the least correlation with the RR interval (r = -0.01) and displayed no significant difference amongst the sexes. As there is no universally recognized formula for preclinical use, the authors recommend developing a best-case scenario model for specific study designs and individual organizations. The data from this research will be helpful in deciding an appropriate QT correction formula for the safety assessment of new pharmaceuticals and biologics.

C-L Case Conference: Torsades de Pointes in a Patient With Lifelong Medical Trauma, COVID-19, Remdesivir, Citalopram, Quetiapine, and Hemodialysis

We present a case of Torsades de Pointes (TdP) in a patient with COVID-19 infection and multiple TdP risk factors including QT-interval prolongation, hemodialysis, bradycardia, and treatment with remdesivir, citalopram, and quetiapine. The case was complicated by post-resuscitation anxiety superimposed on a history of medical trauma since childhood. Top experts in the field of consultation-liaison psychiatry, trauma informed care, and cardiac electrophysiology provide perspectives on this case with a review of the literature. Key teaching topics include identification of TdP risk factors in patients with a complex illness; the necessity for prompt electrophysiology consultation in clinical scenarios with high risk for TdP; and the approach to patients with medical trauma using a trauma-informed lens. We highlight the contributions of COVID-19, the pharmacokinetics of QT-interval-prolonging psychotropic medications, the risks of hemodialysis, and the role of remdesivir-induced bradycardia in this first reported case of TdP in a patient treated with remdesivir.