QTc: how long is too long?

ECG Findings Are Poor Predictors for Adverse Events and Cardiac Death in Barth Syndrome

Background

Patients with Barth syndrome (BTHS) can present with cardiomyopathy. BTHS subjects are at risk for cardiac adverse outcomes throughout life, including malignant arrhythmias and death. Electrocardiogram (ECG) parameters have never been assessed as a tool to predict adverse outcomes in individuals with BTHS.

Objectives

The purpose of this study was to identify any ECG parameters including QRS fragmentation, presence of arrhythmia, or abnormal intervals that could predict adverse outcomes and cardiac death among the BTHS population.

Methods

We performed a retrospective case referent study on subjects with BTHS (n=43), and compared them with our reference group, subjects with idiopathic dilated cardiomyopathy (DCM) from a single institution (n=53) from 2007-2021. BTHS data was obtained from subjects attending the biennial Barth Syndrome Foundation International Scientific, Medical, and Family Conferences (BSFISMFC) from 2002-2018. ECG data from first and last available ECG's prior to an adverse event or cardiac death was analyzed, and then multivariable regression was performed to determine odd ratios between ECG characteristics and adverse events/cardiac death.

Results

No ECG variables were statistically significant predictors of adverse events or cardiac death in the BTHS group. Last ECG QRS fragmentation trended to statistically significance (OR 13.3, p=0.12) in predicting adverse events in the DCM group.

Conclusion

No ECG parameters, including QRS fragmentation, presence of arrhythmia, or abnormal interval values predict adverse events or cardiac death among BTHS patients. QRS fragmentation may be a predictor of adverse events in the DCM population.

Acute, dose-response effects of guayusa leaf extract on mood, cognitive and motor-cognitive performance, and blood pressure, heart rate, and ventricular repolarization

PURPOSE

We conducted a randomized, double-blind, placebo-controlled crossover trial in young adults to examine the dose-dependent (600 mg versus 1200 mg), acute effects of consumption of an Ilex guayusa tea extract (GLE) on mood, cognitive and motor-cognitive performance, as well as its acute cardiovascular effects.

METHODS

Twenty-five adults (mean ± SD, age = 28 ± 7 y; 9 M/16 F) completed familiarization and then three randomly ordered experimental visits where they consumed either 600 mg (GLE600) or 1200 mg (GLE1200) GLE or placebo (PLA). Following supplement consumption, participants completed a mood state survey, assessments of perceived jitteriness, energy, and focus, and neurocognitive and motor-cognitive testing. Blood pressure (BP), heart rate, and QT interval length were determined before and after supplementation.

RESULTS

GLE600 significantly improved total mood disturbance (mean ± SE difference = -6.9 ± 2.6 au, p = 0.034), fatigue-inertia (-2.84 ± 0.89 au, p = 0.008), perceived energy (+13.00 ± 4.49 au; p = 0.02), motor speed (+4.52 ± 1.42 au, p = 0.008), and psychomotor speed (+7.20 ± 2.16 au, p = 0.005) relative to PLA. GLE1200 also improved psychomotor speed (+5.08 ± 2.16 ms, p = 0.045) and uniquely increased motor-cognitive performance as reflected by a decrease in reaction time (-0.106 ± 0.04 ms, p = 0.026) during a neurocognitive hop test. The effect of GLE on jitteriness was both dose- and sex-dependent. Jitteriness increased with increasing GLE dose in women only (p < 0.001). Both GLE600 and GLE1200 similarly increased systolic and diastolic BP by 4-5 mmHg (p ≤ 0.022). Neither GLE600 nor GLE1200 acutely influenced QTc length (p = 0.31).

CONCLUSIONS

The goal of GLE supplementation should be considered when selecting a dosing strategy. Lower dosages of GLE (e.g. 600 mg) appear to optimize cognitive and mood-related outcomes while limiting side-effects such as jitteriness in women, and higher dosages may be necessary (e.g. 1200 mg) to promote improvements in motor-cognitive performance.

Impact of preoperative QTc interval prolongation on short-term postoperative outcomes: A retrospective study

STUDY OBJECTIVE

Although a prolonged heart rate-corrected QT interval (QTcI) is associated with an increased risk of mortality in the general population, its prognostic value in surgical patients remains unclear. We aimed to examine whether preoperative QTcI prolongation predicts short-term postoperative outcomes in elderly patients undergoing noncardiac surgery.

DESIGN

The study was a retrospective analysis using the TriNetX network database.

SETTING

Operating room.

INTERVENTION

Assessment and categorization of preoperative QTcI.

PATIENTS

Data of patients aged ≥65 years who underwent non-cardiac surgery between 2010 and 2023 were analyzed.

MEASUREMENTS

Patients were categorized into four groups based on preoperative QTcI: long (500-600 ms), borderline (460-500 ms), high-normal (420-460 ms) and control (370-420 ms) groups. The groups were compared using a propensity score-matched analysis. The primary outcome was the all-cause 90-day mortality risk. The secondary outcomes included 90-day risks of postoperative new-onset atrial fibrillation (Af), ventricular arrhythmias (VAs), emergency visits, hospital readmissions, and pneumonia.

RESULTS

In total, data on 519,929 patients were collected in this study. Pairwise comparisons showed that all QTcI prolongation groups demonstrated a heightened incidence of postoperative mortality, arrhythmias, and other complications compared to the control group. Patients with a long QTcI had a 3-fold higher risk of mortality (hazard ratio [HR] = 3.124, p < 0.001), Af (HR = 3.059, p < 0.001), and VAs (HR = 3.617, p < 0.001) than controls. The risks of emergency visits (HR = 1.287, p < 0.001), hospital readmissions (HR = 1.591, p < 0.001), and pneumonia (HR = 1.672, p < 0.001) were also higher in the long QTcI group than in the control group. A dose-dependent response was evident between QTcI and mortality as well as arrhythmia risk.

CONCLUSION

Preoperative QTcI screening effectively risk-stratifies elderly surgical patients, with a QTcI≥500 ms being strongly predictive of short-term postoperative mortality and other complications. Incorporating QTcI assessment into the preoperative evaluation may guide perioperative monitoring and management.

Uncovering possible silent acquired long QT syndrome using exercise stress testing in long-term pediatric acute lymphoblastic leukemia survivors

An example of chemotherapy-induced cardiotoxicity in cancer survivors is acquired long QT syndrome (aLQTS), which may cause serious yet preventable life-threatening consequences. Our objective was to identify and characterize childhood acute lymphoblastic leukemia (ALL) survivors with possible aLQTS using maximal exercise testing. In this cross-sectional study with exploratory analysis, a total of 250 childhood ALL survivors were evaluated for abnormal QT interval prolongation using the McMaster cycle exercise test. A total of 198 survivors (102 males; 96 females), having reached theirV ̇ O 2 $$ \dot{\mathrm{V}}{\mathrm{O}}_2 $$ peak (mean 32.1 ± 8.4 mL/kg/min; range 15.5-57.8 mL/kg/min), were included in our analyses. Two survivors were excluded for possible congenital LQTS. QT intervals were corrected for heart rate using the Bazett, Fridericia, and Rautaharju formulas at rest (supine, sitting, and standing positions), at the end of each stage of the CPET, and at 1, 3, and 5 minutes into the recovery period. The corrected QT (QTc) of borderline (n = 37) and long QT survivors (n = 20) was significantly longer than normal survivors (n = 141) at rest, exercise, and recovery. Out of 57 survivors presenting an abnormal QTc prolongation, 40 survivors (70%) showed no QT interval anomalies at rest but developed various anomalies during exercise. No significant differences were found between the groups for any of the measured clinical characteristics or cardiac parameters. The standardization of exercise testing in the regular follow-up of oncology patients is necessary for appropriate cardiac prevention and surveillance to enhance the health and quality of life of the ever-increasing number of cancer survivors.

The Effects of Cycle Ergometer Versus Treadmill Exercise Stress Testing on QTc Interval Prolongation in Patients With Long QT Syndrome: A Systematic Review and Meta-analysis

OBJECTIVE

The safest and most effective exercise stress tests (EST) modalities for long QT syndrome (LQTS) are currently unknown. The main objective was to explore the effects of EST on the corrected QT interval (QTc) in patients with LQTS, and to compare the effects of different EST modalities (cycle ergometer vs treadmill).

DATA SOURCES

Systematic searches were performed in September 2022 in accordance with the PRISMA statement through PubMed, Medline, EBM Reviews, Embase, and Web of Science.

MAIN RESULTS

A total of 1728 patients with LQTS, whether congenital or acquired, without any age restrictions (pediatric age ≤18 years and adult age >19 years), and 2437 control subjects were included in the 49 studies. The QT interval data were available for 15 studies. Our analyses showed that the QT interval prolonged in a similar manner using either a cycle ergometer or a treadmill (standardized mean difference [SMD] = 1.89 [95% CI, 1.07-2.71] vs SMD = 1.46 [95% CI, 0.78-2.14], respectively). Therefore, it seems that either modality may be used to evaluate patients with LQTS.

CONCLUSIONS

The methodology for the measurement of the QT interval was very heterogeneous between studies, which inevitably influenced the quality of the analyses. Hence, researchers should proceed with caution when exploring and interpreting data in the field of exercise and LQTS.

Prevalence of electrocardiographic markers associated with myocardial fibrosis in masters athletes: a cohort study

Objectives

Myocardial fibrosis (MF) is associated with an increased predisposition to adverse cardiac events. The accumulation of high-volume and high-intensity exercise over an extended duration potentially increases the risk of MF. Specific electrocardiographic markers have been correlated with the presence of MF. This study assessed the prevalence of MF-related electrocardiographic markers in a Track and Field Master Athletics Cohort (TaFMAC).

Methods

Twelve-lead resting electrocardiograms (ECGs) were conducted on 155 athletes (90 males and 65 females) participating in the World Masters Athletics 2022. The ECG markers associated with MF, including pathological Q waves, inverted T waves, fragmented QRS complex, and prolonged QRS complex, were compared among different athletic specialities (endurance athletes n=51, sprinters n=69 and strength and power n=35).

Results

Overall, 71 instances of MF-related markers were identified from 155 ECG recordings (46%). Fragmented QRS emerged as the most common marker, with a prevalence of 29% in endurance and strength and power athletes, and 35% in sprinters. No significant group differences were observed in the prevalence of MF markers, whether analysed collectively (p=0.467) or individually (pathological Q waves p=0.367, inverted T waves p=0.309, fragmented QRS complex p=0.747 and prolonged QRS complex p=0.132).

Conclusions

The prevalence of MF markers, as determined by resting ECG, was evident in nearly half of masters athletes, irrespective of sex and sporting specialisation. These findings suggest resting ECG as a promising non-invasive method for the early identification of MF in athlete's hearts.

Deep Learning-Augmented ECG Analysis for Screening and Genotype Prediction of Congenital Long QT Syndrome

Importance

Congenital long QT syndrome (LQTS) is associated with syncope, ventricular arrhythmias, and sudden death. Half of patients with LQTS have a normal or borderline-normal QT interval despite LQTS often being detected by QT prolongation on resting electrocardiography (ECG).

Objective

To develop a deep learning-based neural network for identification of LQTS and differentiation of genotypes (LQTS1 and LQTS2) using 12-lead ECG.

Design, Setting, and Participants

This diagnostic accuracy study used ECGs from patients with suspected inherited arrhythmia enrolled in the Hearts in Rhythm Organization Registry (HiRO) from August 2012 to December 2021. The internal dataset was derived at 2 sites and an external validation dataset at 4 sites within the HiRO Registry; an additional cross-sectional validation dataset was from the Montreal Heart Institute. The cohort with LQTS included probands and relatives with pathogenic or likely pathogenic variants in KCNQ1 or KCNH2 genes with normal or prolonged corrected QT (QTc) intervals.

Exposures

Convolutional neural network (CNN) discrimination between LQTS1, LQTS2, and negative genetic test results.

Main Outcomes and Measures

The main outcomes were area under the curve (AUC), F1 scores, and sensitivity for detecting LQTS and differentiating genotypes using a CNN method compared with QTc-based detection.

Results

A total of 4521 ECGs from 990 patients (mean [SD] age, 42 [18] years; 589 [59.5%] female) were analyzed. External validation within the national registry (101 patients) demonstrated the CNN's high diagnostic capacity for LQTS detection (AUC, 0.93; 95% CI, 0.89-0.96) and genotype differentiation (AUC, 0.91; 95% CI, 0.86-0.96). This surpassed expert-measured QTc intervals in detecting LQTS (F1 score, 0.84 [95% CI, 0.78-0.90] vs 0.22 [95% CI, 0.13-0.31]; sensitivity, 0.90 [95% CI, 0.86-0.94] vs 0.36 [95% CI, 0.23-0.47]), including in patients with normal or borderline QTc intervals (F1 score, 0.70 [95% CI, 0.40-1.00]; sensitivity, 0.78 [95% CI, 0.53-0.95]). In further validation in a cross-sectional cohort (406 patients) of high-risk patients and genotype-negative controls, the CNN detected LQTS with an AUC of 0.81 (95% CI, 0.80-0.85), which was better than QTc interval-based detection (AUC, 0.74; 95% CI, 0.69-0.78).

Conclusions and Relevance

The deep learning model improved detection of congenital LQTS from resting ECGs and allowed for differentiation between the 2 most common genetic subtypes. Broader validation over an unselected general population may support application of this model to patients with suspected LQTS.

A Novel Variant in AKAP9 Gene, a Controversial Gene, in Long QT Syndrome

Introduction

Long QT syndrome (LQTS) is a common congenital cause of fatal cardiac arrhythmia. Characteristic clinical findings are prolonged QT interval and ventricular arrhythmia on electrocardiogram (ECG), syncope, seizure, and sudden death. It is a genetically heterogeneous disease. To date, disease-causing variant have been reported in seventeen genes. The AKAP9 is still considered controversial among those genes.

Case Report

We report the case of a 10-year-old female who was born from a non-consanguineous Turkish couple. She visited pediatrics cardiology clinic presenting with dyspnea and tachycardia. Prolongation of the QT interval was detected in her ECG. Panel test associated with LQTS genes was performed. She was diagnosed with long QTS type 11 due to a heterozygous variant in AKAP9:c.11487_11489 delTACinsCGTA, p.(Thr3830ValfsTer12), that was revealed through next-generation sequencing test. The variant was also found in her mother and brother.

Discussion and Conclusion

Novel heterozygous frameshift variant in the AKAP9 gene was considered as "Uncertain Significance (VUS)" in the ACMG classification. The novel variant is absent from population databases (PM2); it is a null variant (PVS1_moderate). AKAP9 gene has the lowest known rate among the causes of LQTS. Information is limited on genotype-phenotype correlation. Yet it is still among the candidate genes. Although the relationship of the AKAP9 gene with LQTS has not yet been fully indicated, individuals with a pathogenic variant in AKAP9 gene and silent carriers may be at risk for fatal cardiac events. Improvements of the genetic tests in the near future may contribute to the literature and clinical research about AKAP9 gene.

Developing a Model for Quantifying QTc-Prolongation Risk to Enhance Medication Safety Assessment: A Retrospective Analysis

There are currently no established methods to predict quantitatively whether the start of a drug with the potential to prolong the QTc interval poses patients at risk for relevant QTc prolongation. Therefore, this retrospective study aimed to pave the way for the development of models for estimating QTc prolongation in patients newly exposed to medications with QTc-prolonging potential. Data of patients with a documented QTc prolongation after initiation of a QTc-prolonging drug were extracted from hospital charts. Using a standard model-building approach, general linear mixed models were identified as the best models for predicting both the extent of QTc prolongation and its absolute value after the start of a QTc-time-prolonging drug. The cohort consisted of 107 adults with a mean age of 64.2 years. Patients were taking an average of 2.4 drugs associated with QTc prolongation, with amiodarone, propofol, pipamperone, ondansetron, and mirtazapine being the most frequently involved. There was a significant but weak correlation between measured and predicted absolute QTc values under medication (r2 = 0.262, p < 0.05), as well as for QTc prolongation (r2 = 0.238, p < 0.05). As the developed models are based on a relatively small number of subjects, further research is necessary to ensure their applicability and reliability in real-world scenarios. Overall, this research contributes to the understanding of QTc prolongation and its association with medications, providing insight into the development of predictive models. With improvements, these models could potentially aid healthcare professionals in assessing the risk of QTc prolongation before adding a new drug and in making informed decisions in clinical settings.

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.

Serial electrocardiogram recordings revealed a high prevalence of QT interval prolongation in patients with tuberculosis receiving fluoroquinolones

BACKGROUND

Fluoroquinolones, crucial components of treatment regimens for drug-resistant tuberculosis (TB), are associated with QT interval prolongation and risks of fatal cardiac arrhythmias. However, few studies have explored dynamic changes in the QT interval in patients receiving QT-prolonging agents.

METHODS

This prospective cohort study recruited hospitalized patients with TB who received fluoroquinolones. The study investigated the variability of the QT interval by using serial electrocardiograms (ECGs) recorded four times daily. This study analyzed the accuracy of intermittent and single-lead ECG monitoring in detecting QT interval prolongation.

RESULTS

This study included 32 patients. The mean age was 68.6 ± 13.2 years. The results revealed mild-to-moderate and severe QT interval prolongation in 13 (41%) and 5 (16%) patients, respectively. The incremental yields in sensitivity of one to four daily ECG recordings were 61.0%, 26.1%, 5.6%, and 7.3% in detecting mild-to-moderate QT interval prolongation, and 66.7%, 20.0%, 6.7%, and 6.7% in detecting severe QT interval prolongation. The sensitivity levels of lead II and V5 ECGs in detecting mild-to-moderate and severe QT interval prolongation exceeded 80%, and their specificity levels exceeded 95%.

CONCLUSION

This study revealed a high prevalence of QT interval prolongation in older patients with TB who receive fluoroquinolones, particularly those with multiple cardiovascular risk factors. Sparsely intermittent ECG monitoring, the prevailing strategy in active drug safety monitoring programs, is inadequate owing to multifactorial and circadian QT interval variability. Additional studies performing serial ECG monitoring are warranted to enhance the understanding of dynamic QT interval changes in patients receiving QT-prolonging anti-TB agents.

Impact of Fluoroquinolone Susceptibility Suppression on Discharge Prescribing for Acute Uncomplicated Cystitis

Background

Fluoroquinolones (FQs) are associated with adverse effects and increasing resistance. However, uncomplicated cystitis remains a frequent reason for FQ use. Selective reporting involves withholding susceptibilities for select antimicrobial agents on microbiology reports, in hopes of dissuading use by providers. The purpose of this study was to investigate the impact of FQ susceptibility suppression on discharge prescribing for hospitalized patients with uncomplicated cystitis.

Methods

This retrospective quasi-experimental analysis was conducted among adult patients at a 350-bed academic medical center. Its aim was to compare the incidence of FQ prescribing for cystitis at hospital discharge, one year before and after implementation (1 March 2017-31 March 2019) of a policy to suppress FQ urinary susceptibility results for pansusceptible Klebsiella spp and Escherichia coli. FQ appropriateness and risk factors for FQ use were also examined.

Results

There was a relative risk reduction of 39% in discharge FQ prescribing when adjusted for discharge team (adjusted risk ratio, 0.61; 95% CI, .40-.93). Almost all FQ use was inappropriate, largely due to organisms' susceptibility to a guideline-preferred agent (n = 61). In multivariate analysis, odds ratios of discharge FQ prescribing were 0.22 (95% CI, .12-.39) for insured patients, 0.43 (95% CI, .21-.86) for patients with antibiotic allergy, and 57.8 (95% CI, 13.7-244) for those receiving inpatient FQ. Discharge from a medicine team was protective against discharge FQ prescribing.

Conclusions

With multidisciplinary inpatient medicine services and avoidance of inpatient FQ use, suppression of FQ susceptibilities on pansusceptible urine isolates for Klebsiella spp and E coli may represent an attractive strategy for antibiotic stewardship at hospital discharge.

KCNH2 mutation c.3099_3112del causes congenital long QT syndrome type 2 with gender differences

INTRODUCTION

Long QT Syndrome (LQTS) is an inherited disease with an abnormal electrical conduction system in the heart that can cause sudden death as a result of QT prolongation. LQT2 is the second most common subtype of LQTS caused by loss of function mutations in the potassium voltage-gated channel subfamily H member 2 (KCNH2) gene. Although more than 900 mutations are associated with the LQTS, many of these mutations are not validated or characterized.

METHODS AND RESULTS

Sequencing analyses of genomic DNA of a family with LQT2 identified a putative mutation. i.e., KCNH2(NM_000238.3): c.3099_3112del, in KCNH2 gene which appeared to be a definite pathogenic mutation. The family pedigree information showed a gender difference in clinical features and T-wave morphology between male and female patients. The female with mutation exhibited recurring ventricular arrhythmia and syncope, while two male carriers did not show any symptoms. In addition, T-wave in females was much flatter than in males. The female proband showed a positive reaction to the lidocaine test. Lidocaine injection almost completely blocked ventricular arrhythmia and shortened the QT interval by ≥30 ms. Treatment with propranolol, mexiletine, and implantation of cardioverter-defibrillators prevented the sustained ventricular tachycardia, ventricular fibrillation, and syncope, as assessed by a 3-year follow-up evaluation.

CONCLUSIONS

A putative mutation c.3099_3112del in the KCNH2 gene causes LQT2 syndrome, and the pathogenic mutation mainly causes symptoms in female progeny.

Corrected QT interval in cirrhosis: A systematic review and meta-analysis

BACKGROUND

Corrected QT (QTc) interval is prolonged in patients with liver cirrhosis and has been proposed to correlate with the severity of the disease. However, the effects of sex, age, severity, and etiology of cirrhosis on QTc have not been elucidated. At the same time, the role of treatment, acute illness, and liver transplantation (Tx) remains largely unknown.

AIM

To determine the mean QTc in patients with cirrhosis, assess whether QTc is prolonged in patients with cirrhosis, and investigate whether QTc is affected by factors such as sex, age, severity, etiology, treatment, acute illness, and liver Tx.

METHODS

In the present systematic review and meta-analysis, the searching protocol "{[QTc] OR [QT interval] OR [QT-interval] OR [Q-T syndrome]} AND {[cirrhosis] OR [Child-Pugh] OR [MELD]}" was applied in PubMed, EMBASE, and Google Scholar databases to identify studies that reported QTc in patients with cirrhosis and published after 1998. Seventy-three studies were considered eligible. Data concerning first author, year of publication, type of study, method used, sample size, mean age, female ratio, alcoholic etiology of cirrhosis ratio, Child-Pugh A/B/C ratio, mean model for end-stage liver disease (MELD) score, treatment with β-blockers, episode of acute gastrointestinal bleeding, formula for QT correction, mean pulse rate, QTc in patients with cirrhosis and controls, and QTc according to etiology of cirrhosis, sex, Child-Pugh stage, MELD score, and liver Tx status (pre-Tx/post-Tx) were retrieved. The Newcastle-Ottawa quality assessment scale appraised the quality of the eligible studies. Effect estimates, expressed as proportions or standardized mean differences, were combined using the random-effects, generic inverse variance method of DerSimonian and Laird. Subgroup, sensitivity analysis, and meta-regressions were applied to assess heterogeneity. The study has been registered in the PROSPERO database (CRD42023416595).

RESULTS

QTc combined mean in patients with cirrhosis was 444.8 ms [95% confidence interval (CI): 440.4-449.2; P < 0.001 when compared with the upper normal limit of 440 ms], presenting high heterogeneity (I2 = 97.5%; 95%CI: 97.2%-97.8%); both Egger's and Begg's tests showed non-significance. QTc was elongated in patients with cirrhosis compared with controls (P < 0.001). QTc was longer in patients with Child-Pugh C cirrhosis when compared with Child-Pugh B and A (P < 0.001); Child-Pugh B patients presented longer QTc when compared with Child-Pugh A patients (P = 0.003). The MELD score was higher in patients with cirrhosis with QTc > 440 ms when compared with QTc ≤ 440 ms (P < 0.001). No correlation of QTc with age (P = 0.693), sex (P = 0.753), or etiology (P = 0.418) was detected. β-blockers shortened QTc (P< 0.001). QTc was prolonged during acute gastrointestinal bleeding (P = 0.020). Tx tended to improve QTc (P < 0.001). No other sources of QTc heterogeneity were revealed.

CONCLUSION

QTc is prolonged in cirrhosis independently of sex, age, and etiology but is correlated with severity and affected by β-blockers and acute gastrointestinal bleeding. QTc is improved after liver Tx.

Preclinical safety and biodistribution assessment of Ad-KCNH2-G628S administered via atrial painting in New Zealand white rabbits

Post-operative atrial fibrillation (POAF) is the most common complication after cardiac surgery. Despite implementation of several pharmacological strategies, incidence of POAF remains at approximately 30%. An adenovirus vector encoding KCNH2-G628S has proven efficacious in a porcine model of AF. In this preclinical study, 1.5 × 1010 or 1.5 × 1012 Ad-KCNH2-G628S vector particles (vp) were applied to the atrial epicardium or 1.5 × 1012 vp were applied to the whole epicardial surface of New Zealand White rabbits. Saline and vector vehicle served as procedure controls. Animals were followed for up to 42 days. Vector genomes persisted in the atria up to 42 days, with no distribution to extra-thoracic organs. There were no adverse effects attributable to test article on standard toxicological endpoints or on blood pressure, left atrial or ventricular ejection fractions, electrocardiographic parameters, or serum IL-6 or troponin concentrations. Mononuclear infiltration of the myocardium of the atrial free walls of low-dose, but not high-dose animals was observed at 7 and 21 days, but these changes did not persist or affect cardiac function. After scaling for heart size, results indicate the test article is safe at doses up to 25 times the maximum proposed for the human clinical trial.

Electrocardiographic QTc as a Surrogate Measure of Cardiac Risk in Children, Adolescents, and Young Adults With Eating Disorders

The study goal was to investigate electrocardiographic findings, including corrected QT interval (QTc), in patients aged 8 to 23 with eating disorders (EDs) at presentation, compared with an age-and sex-matched control population. We retrospectively reviewed 200 ED patients, and 200 controls. Blinded electrocardiograms (ECGs) were interpreted by an expert reader, and QT intervals corrected using the Bazett formula. Eating disorder patients were 89.5% female, with mean age 16.4 years and median percent median body mass index (BMI)-for-age (%mBMI)a of 91.1%. In ED patients, QTc was significantly shorter than controls (399.6 vs 415.0msec, P < .001). After adjusting for height, %mBMI, sex, magnesium level, and bradycardia, mean QTc duration in patients with anorexia nervosa-restricting subtype (AN-R) was significantly shorter than other ED patients (P = .010). Higher %mBMI was associated with shorter QTc duration (P = .041) after adjusting for height, magnesium, bradycardia, and Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) diagnosis. Within the ED group, no significant association was identified between QTc and medications, electrolytes, or inpatient status.

Cardiovascular risk factors and metabolic syndrome in patients treated with long-acting injectables antipsychotics: a retrospective study

The present cross-sectional, retrospective study aimed to assess the prevalence of cardiovascular disease (CVD) risk factors and metabolic syndrome in a sample of psychiatric patients treated with long-acting injectable antipsychotics (LAIs). The clinical charts of 120 patients, mainly diagnosed with schizophrenia (30.0%), schizoaffective disorder (15.0%), and bipolar disorder (13.3%) on LAIs therapy - initiated in the period from 2013 to 2019 and lasting at least one year - were retrospectively reviewed and related socio-demographic, clinical and laboratory variables were collected. The 70.8% of patients were treated with first-generation LAIs, and the remaining 29.2% with second-generation LAIs. The overall sample showed low compliance in performing the required exams and evaluations related to CVD risk factors. The prevalence of metabolic syndrome was 30.8%, and, considering specific CVD risk factors, 55% of the total sample reported abdominal obesity, 43.3% arterial hypertension, 41.7% low HDL-cholesterol, 25.8% hypertriglyceridemia, and 20.8% fasting hyperglycemia. Lastly, 6.7% showed prolonged corrected QT (QTc) interval at the ECG. Patients treated with LAIs should be regularly monitored for metabolic changes and CVD risk factors. Metabolic changes rapidly develop after initiating an antipsychotic therapy and these often involve parameters, that can be easily recorded in an outpatient setting (e.g. abdominal obesity and hypertension).

Long QTc in hypertrophic cardiomyopathy: A consequence of structural myocardial damage or a distinct genetic disease?

Hypertrophic cardiomyopathy (HCM) is an autosomal dominant disease, characterized by the presence of unexplained left ventricular hypertrophy. This condition is often associated with electrocardiographic abnormalities including QTc prolongation occurring in 13% of patients. The main explanation for prolonged QTc in HCM is myocardial hypertrophy and the related structural damage. However, other mechanisms, including long QT syndrome (LQTS) genes mutations, may be involved. In the present study we explored the hypothesis of a distinct genetic basis underlying QTc prolongation in HCM by investigating the potential co-inheritance of pathogenic gene variants associated with LQTS and HCM. For this purpose, starting from a cohort of 150 HCM patients carrying pathogenic variants in sarcomere genes, we selected 25 patients carrying a QTc prolongation unexplained by any other cause. The QTc was considered prolonged if greater than 450 ms in males and greater than 470 ms in females. The NGS analysis was performed with Illumina TrueSight Cardio panel genes on Illumina MiniSeq platform. We identified pathogenic/likely pathogenic variants in the KCNQ1 in two patients (c.1781G &gt; A, p. Arg594Gln; c.532G &gt; A, p. Ala178Thr) (8%). Variants of uncertain significance were identified in SCN5A, KCNJ5, AKAP9 and ANK2 in four patients (16%). Although the results are limited by the small number of patients included in the study, they highlight a minor contribution of LQTS genes for QTc prolongation in HCM patients. The screening for ion channel genes mutations may be considered in HCM patients with prolonged QTc unexplained by any other cause. This in-depth molecular diagnosis may contribute to improve risk stratification and treatment planning.

Action potential metrics and automated data analysis pipeline for cardiotoxicity testing using optically mapped hiPSC-derived 3D cardiac microtissues

Recent advances in human induced pluripotent stem cell (hiPSC)-derived cardiac microtissues provide a unique opportunity for cardiotoxic assessment of pharmaceutical and environmental compounds. Here, we developed a series of automated data processing algorithms to assess changes in action potential (AP) properties for cardiotoxicity testing in 3D engineered cardiac microtissues generated from hiPSC-derived cardiomyocytes (hiPSC-CMs). Purified hiPSC-CMs were mixed with 5-25% human cardiac fibroblasts (hCFs) under scaffold-free conditions and allowed to self-assemble into 3D spherical microtissues in 35-microwell agarose gels. Optical mapping was performed to quantify electrophysiological changes. To increase throughput, AP traces from 4x4 cardiac microtissues were simultaneously acquired with a voltage sensitive dye and a CMOS camera. Individual microtissues showing APs were identified using automated thresholding after Fourier transforming traces. An asymmetric least squares method was used to correct non-uniform background and baseline drift, and the fluorescence was normalized (ΔF/F0). Bilateral filtering was applied to preserve the sharpness of the AP upstroke. AP shape changes under selective ion channel block were characterized using AP metrics including stimulation delay, rise time of AP upstroke, APD30, APD50, APD80, APDmxr (maximum rate change of repolarization), and AP triangulation (APDtri = APDmxr-APD50). We also characterized changes in AP metrics under various ion channel block conditions with multi-class logistic regression and feature extraction using principal component analysis of human AP computer simulations. Simulation results were validated experimentally with selective pharmacological ion channel blockers. In conclusion, this simple and robust automated data analysis pipeline for evaluating key AP metrics provides an excellent in vitro cardiotoxicity testing platform for a wide range of environmental and pharmaceutical compounds.

Guide to the Female Student Athlete ECG: A Comprehensive Study of 3466 Young, Racially Diverse Athletes

OBJECTIVES

The 12-lead electrocardiogram (ECG) is used in the preparticipation screening examination for athletes. Despite known differences in ECG findings by sex, only QTc prolongation is given a sex-specific threshold. We hypothesize that our large dataset-with diversity in age, race, and sport participation-can be utilized to improve ECG screening in female student athletes.

METHODS

Computerized 12-lead ECGs were recorded and analyzed in female athletes who underwent preparticipation screening examination between June 2010 and September 2021. The quantitative, empirical 2017 international criteria for electrocardiographic interpretation were compared with either the 99th percentile in our cohort or the percentile that corresponded to the known disease prevalence.

RESULTS

Of 3466 female athletes with ECGs as part of preparticipation screening examination, the 2017 international criteria classified 2.1% of athletes with at least one ECG abnormality requiring cardiological evaluation. Rates were similar across age, race/ethnicity, and sporting discipline. Using ranges based on our population, 2.7% of athletes would require additional workup. Surprisingly, ST depression up to 0.03 mV was a normal finding in this cohort. If RS voltage extremes were considered findings requiring follow-up, an additional 9.6% of the athlete population would be flagged using current definitions. This number decreases to 2.7% if using the 99th percentile in this cohort.

CONCLUSION

These results highlight a difference in the reported prevalence of ECG abnormalities when comparing empirically derived thresholds to statistically derived ranges. Consideration of new metrics specific to the female athlete population has the potential to further refine athlete ECG screening.

AKAP9-Related Channelopathy: Novel Pathogenic Variant and Review of the Literature

Disease-associated pathogenic variants in the A-Kinase Anchor Protein 9 (AKAP9) (MIM *604001) have been recently identified in patients with autosomal dominant long QT syndrome 11 (MIM #611820), lethal arrhythmia (ventricular fibrillation, polymorphic ventricular tachycardia), Brugada syndrome, and sudden unexpected death. However, AKAP9 sequence variations were rarely reported and AKAP9 was classified as a "disputed evidence" gene to support disease causation due to the insufficient genetic evidence and a limited number of reported AKAP9-mutated patients. Here, we describe a 47-year-old male carrying a novel frameshift AKAP9 pathogenic variant who presented recurrent syncopal attacks and sudden cardiac arrest that required a semi-automatic external defibrillator implant and an electric shock treatment of ventricular arrhythmia. This study provides insight into the mechanism underlying cardiac arrest and confirms that AKAP9 loss-of-function variants predispose to serious, life-threatening ventricular arrhythmias.

Frequency of QTc Interval Prolongation in Children and Adults with Williams Syndrome

QTc prolongation (≥ 460 ms), according to Bazett formula (QTcB), has been identified to be increased in Williams syndrome (WS) and suggested as a potential cause of increased risk of sudden cardiac death. The Bazett formula tends to overestimate QTc in higher heart rates. We performed a retrospective chart review of WS patients with ≥ 1 electrocardiogram (EKG) with sinus rhythm, no evidence of bundle branch blocks, and measurable intervals. A total of 280 EKGs from 147 patients with WS were analyzed and 123 EKGs from 123 controls. The QTc was calculated using Bazett formula. The average QTcB for individuals with WS and controls was 444 ± 24 ms and 417 ± 26 ms, respectively (p < 0.001). In our WS cohort 34.4% had at least 1 EKG with a QTcB ≥ 460 ms. The mean heart rate (HR) from patients with WS was significantly higher than controls (96 bpm vs 76 bpm, p < 0.001). Linear regression showed that HR contributed 27% to QTcB prolongation in the patients with WS. Patients with WS have a mean QTcB in the normal range but higher than controls, and a higher than expected frequency of QTc ≥ 460 ms compared to the general population. HR is also higher in WS and contributes modestly to the WS QTcB prolongation. Future studies are needed to assess if these findings contribute risk to sudden cardiac death but in the interim we recommend routine EKG testing, especially when starting QTc prolonging medications.

Sex Differences and Utility of Treadmill Testing in Long‐QT Syndrome

Background

Diagnosis of congenital long‐QT syndrome (LQTS) is complicated by phenotypic ambiguity, with a frequent normal‐to‐borderline resting QT interval. A 3‐step algorithm based on exercise response of the corrected QT interval (QTc) was previously developed to diagnose patients with LQTS and predict subtype. This study evaluated the 3‐step algorithm in a population that is more representative of the general population with LQTS with milder phenotypes and establishes sex‐specific cutoffs beyond the resting QTc.

Methods and Results

We identified 208 LQTS likely pathogenic or pathogenic KCNQ1 or KCNH2 variant carriers in the Canadian NLQTS (National Long‐QT Syndrome) Registry and 215 unaffected controls from the HiRO (Hearts in Rhythm Organization) Registry. Exercise treadmill tests were analyzed across the 5 stages of the Bruce protocol. The predictive value of exercise ECG characteristics was analyzed using receiver operating characteristic curve analysis to identify optimal cutoff values. A total of 78% of male carriers and 74% of female carriers had a resting QTc value in the normal‐to‐borderline range. The 4‐minute recovery QTc demonstrated the best predictive value for carrier status in both sexes, with better LQTS ascertainment in female patients (area under the curve, 0.90 versus 0.82), with greater sensitivity and specificity. The optimal cutoff value for the 4‐minute recovery period was 440 milliseconds for male patients and 450 milliseconds for female patients. The 1‐minute recovery QTc had the best predictive value in female patients for differentiating LQTS1 versus LQTS2 (area under the curve, 0.82), and the peak exercise QTc had a marginally better predictive value in male patients for subtype with (area under the curve, 0.71). The optimal cutoff value for the 1‐minute recovery period was 435 milliseconds for male patients and 455 milliseconds for femal patients.

Conclusions

The 3‐step QT exercise algorithm is a valid tool for the diagnosis of LQTS in a general population with more frequent ambiguity in phenotype. The algorithm is a simple and reliable method for the identification and prediction of the 2 major genotypes of LQTS.

Importance of Formula-Specific Centile Thresholds for Evaluation of Heart Rate-Corrected QT Prolongation in Williams Syndrome

Patients with Williams syndrome (WS) have a 25- to 100-fold higher risk of sudden death and prolonged heart rate-corrected QT (QTc). A recent study using the Fridericia formula for QT correction suggested that prolongation is principally an issue of heart rate. We used multiple published heart rate correction formulas to reevaluate the prevalence of QTc prolongation in our original dataset from our 2010 study at the Children's Hospital of Philadelphia. The ninety-eighth centile for QTc and corrected JT Interval (JTc) of the control population for each formula were used to set the threshold for prolongation. Prevalence comparison was done with Fisher's exact test. Predictors of longer QTc/JTc were assessed using linear regression models adjusting for age, gender, and heart rate. Adjusted odds of QTc/JTc prolongation were evaluated with conditional logistic regression models matched based on age and heart rate. There were 482 electrocardiograms from 188 patients with WS and 1,522 from normal controls. Patients with WS were younger, with higher heart rates and shorter RR and QRS intervals. WS was associated with longer QTc/JTc compared with controls. There were higher odds of prolonged QTc/JTc in patients with WS than controls using both Bazett and Fridericia formulas. In conclusion, this study confirms the higher prevalence of QTc prolongation in WS compared with controls and highlights the importance of setting appropriate formula-specific upper thresholds for QTc prolongation for accurate diagnosis.

ECG T-Wave Morphologic Variations Predict Ventricular Arrhythmic Risk in Low- and Moderate-Risk Populations

Background Early identification of individuals at risk of sudden cardiac death (SCD) remains a major challenge. The ECG is a simple, common test, with potential for large-scale application. We developed and tested the predictive value of a novel index quantifying T-wave morphologic variations with respect to a normal reference (TMV), which only requires one beat and a single-lead ECG. Methods and Results We obtained reference T-wave morphologies from 23 962 participants in the UK Biobank study. With Cox models, we determined the association between TMV and life-threatening ventricular arrhythmia in an independent data set from UK Biobank study without a history of cardiovascular events (N=51 794; median follow-up of 122 months) and SCD in patients with coronary artery disease from ARTEMIS (N=1872; median follow-up of 60 months). In UK Biobank study, 220 (0.4%) individuals developed life-threatening ventricular arrhythmias. TMV was significantly associated with life-threatening ventricular arrhythmias (hazard ratio [HR] of 1.13 per SD increase [95% CI, 1.03-1.24]; P=0.009). In ARTEMIS, 34 (1.8%) individuals reached the primary end point. Patients with TMV ≥5 had an HR for SCD of 2.86 (95% CI, 1.40-5.84; P=0.004) with respect to those with TMV <5, independently from QRS duration, corrected QT interval, and left ventricular ejection fraction. TMV was not significantly associated with death from a cause other than SCD. Conclusions TMV identifies individuals at life-threatening ventricular arrhythmia and SCD risk using a single-beat single-lead ECG, enabling inexpensive, quick, and safe risk assessment in large populations.

Increasing Daily Physical Activity and Its Effects on QTc Time in Severe to Very Severe COPD: A Secondary Analysis of a Randomised Controlled Trial

Approximately, half of COPD patients die from cardiovascular diseases. A prolongation of cardiac repolarization (measured as QTc interval) is associated with cardiovascular events or cardiovascular deaths in populations of older adults and COPD. One way to reduce the QTc could be to increase physical activity (PA). We investigated whether QTc can be reduced by an increase in PA in patients with severe COPD. This is a secondary outcome analysis from a randomized controlled trial investigating the effects of a 3 months pedometer based program to improve PA. 12-lead ECG was assessed at baseline and after 3 months. We measured PA using a validated triaxial accelerometer. Data were analyzed from 59 participants. Multiple regression modeling, including adjustment for baseline QTc, sex, QT prolonging medications, BMI, smoking status and FEV1%, showed no evidence for an association between an improvement of ≥15% PA and QTc reduction. A 15% improvement in PA according to step counts over 3 months seems not to reduce QTc interval by its MCID of 20 ms in patients with severe to very severe COPD.

Role of electrocardiogram findings in predicting 48-h mortality in patients with traumatic brain injury

OBJECTIVE

Electrocardiogram (ECG) patterns can change, especially in patients with central nervous system disorders such as spontaneous subarachnoid hemorrhage. However, the association between the prognosis of traumatic brain injury (TBI) and ECG findings is unknown. Therefore, this study aimed to compare and to analyze ECG findings to predict early mortality in patients with TBI.

METHODS

This retrospective observational study included patients with severe trauma and TBI who were admitted to the emergency department (ED) between January 2018 and December 2020. TBI was defined as an abbreviated injury scale score of the head of ≥3. We examined ECG findings, including PR prolongation (≥ 200 ms), QRS complex widening (≥ 120 ms), corrected QT interval prolongation (QTP, ≥ 480 ms), ST-segment elevation, and ST-segment depression (STD) at ED arrival. The primary outcome was 48-h mortality.

RESULTS

Of the total patients with TBI, 1024 patients were included in this study and 48-h mortality occurred in 89 patients (8.7%). In multivariate analysis, QTP (odds ratio [OR], 2.017; confidence interval [CI], 1.203-3.382) and STD (OR, 8.428; 95% CI, 5.019-14.152) were independently associated with 48-h mortality in patients with TBI. The areas under the curve (AUCs) of the revised trauma score (RTS), injury severity score (ISS), QTP, STD, and the combination of QTP and STD were 0.790 (95% CI, 0.764-0.815), 0.632 (95% CI, 0.602-0.662), 0.605 (95% CI, 0.574-0.635), 0.723 (95% CI, 0.695-0.750), and 0.786 (95% CI, 0.759-0.811), respectively. The AUC of the combination of QTP and STD significantly differed from that of ISS, QTP, and STD, but not RTS.

CONCLUSION

Based on the ECG findings, QTP and STD were associated with 48-h mortality in patients with TBI.

Electrocardiogram in Pediatric Syncope: Practice Variation Among Pediatric Emergency Physicians

OBJECTIVES

We intended to assess emergency department physician's practice pattern and their motivations for obtaining electrocardiograms (ECGs) in pediatric vasovagal syncope presentations. We also explored if borderline ECG findings alters emergency department physicians' management in this population.

METHODS

We conducted a cross-sectional survey of emergency physicians enrolled in the Pediatric Emergency Research Canada network. The survey questionnaire introduced 2 clinical vignettes presenting a typical vasovagal syncope and a presentation suggestive of a cardiac etiology. Outcome measures included frequency investigations, specialist consultation, and disposition stratified by type of syncope presentation. We also evaluated which specific ECG findings were likely to change physicians' management and explored factors influencing the decision to perform or not perform the ECG.

RESULTS

The analyzable response rate was 47% (105/225). In the low-risk scenario, 51% of respondents requested an ECG, and none consulted the cardiology service, given that all requested investigations are normal. Forty-five percent of physicians modified their management if an ECG was reported as anything but totally normal. In the high-risk scenario, all respondents requested either a 12-lead ECG or a high-lead ECG, and 94% consulted the cardiology service. Physicians also identified clear differences in the motivations behind their decision to perform an ECG in typical vasovagal syncope.

CONCLUSIONS

This study highlights the significant practice variation in the evaluation and management of typical vasovagal syncope among physicians, which is informed by complex interactions of patient, provider, and institutional factors and the perceived clinical significance of borderline ECG findings.

QTc prolongation in patients with COVID-19: a retrospective chart review

Drug-induced corrected QT (QTc) prolongation can cause Torsade de Pointes (TdP) which leads to severe arrhythmia or sudden cardiac death. However, information on the prevalence of QTc prolongation in coronavirus disease 2019 (COVID-19) patients and risk factors is limited. A retrospective chart review was conducted in COVID-19 patients admitted to Chonburi Hospital from April to October 2020. The outcomes were the incidence of QTc prolongation and prevalence of risk factor QTc prolongation. We included 29 COVID-19 patients. After treatments were initiated, QTc prolongation occurred in 17 patients (58.62%). QT prolongation could be found as early as two days after the treatment initiation (median = 6 days interquartile range [IQR], 4-7). The median QTc interval in those 17 patients increased from 410 (IQR, 399.5-425.0) ms to 460 (453.50-466.50) ms, with the maximum QTc interval of 488 ms. They were treated with multiple drugs that were reported as a cause of QTc prolongation. 64.71% (n = 11) of them were treated with chloroquine. The median TdP risk score in patients with and without QTc prolongation was 3 (IQR, 2-3) and 2 (IQR, 1-2), respectively. The percentage of patients with comorbidities including atrial fibrillation, bradycardia, concomitant use of diuretics, diabetes, electrolyte imbalance was higher in patients with QTc prolongation. COVID-19 patients were treated with multiple drugs that were reported as a cause of QTc prolongation. COVID-19 patients with QTc prolongation had more comorbidities that are risk factors for QTc prolongation.

Repolarization in systemic sclerosis: a meta-analysis

OBJECTIVES

Systemic sclerosis (SSc) is a rare connective tissue disease characterized by immune dysregulation, vascular damage, and increased deposition of extracellular matrix. In SSc, cardiac manifestations are common and account for 14% of deaths. Numerous studies have examined electrocardiographic findings in SSc patients yielding conflicting reports regarding QTc duration. We conducted a systematic review and meta-analysis of existing studies to investigate whether QTc duration may aid in diagnosis and risk stratification of SSc patients.

METHODS

Two electronic databases (PubMed and Embase) were searched for case-control and cohort studies assessing QTc duration in SSc patients published before March 1, 2021. A random-effects model was used to meta-analyze the results, and included studies were tested for heterogeneity. Linear regression was performed to determine correlations between comorbidities, and QTc duration.

RESULTS

Ninety-six studies, abstracts, and posters were identified. After abstract review and duplicate removal, 23 manuscripts remained. After application of the inclusion and exclusion criteria, 10 studies remained which were quantitatively analyzed. The weighted mean QTc was found to be 422.21 ms for SSc patients and 411.43 ms for control subjects. A significant increase in QTc duration among SSc patients was found, with a standardized mean difference of 0.59 (p < 0.01, 95% CI 0.27-0.92). No significant correlation was found between underlying traits and QTc values. Substantial heterogeneity was found between the studies (I² = 83%, p < 0.01).

CONCLUSION

A significant increase in QTc duration is observed in SSc patients, though the absolute prolongation is not extreme. Therefore, the clinical utility of this finding is unclear and merits large prospective observations. Key Points • A statistically significant prolongation of the QTc interval exists in patients with systemic sclerosis. • Absolute QTc differences between healthy controls and scleroderma patients are not extreme, and, as such, may be of limited clinical utility. • When assessing the underlying traits of systemic sclerosis patients, no statistically significant correlations were found between underlying parameters and QTc duration.

QTc interval on 24-hour holter monitor: To trust or not to trust?

Introduction

QT interval represents the ventricular depolarization and repolarization. Its accurate measurement is critical since prolonged QT can lead to sudden cardiac death. QT is affected by heart rate and is corrected to QTc via several formulae. QTc is commonly calculated on the ECG and not the 24‐h Holter.

Methods

100 patients presenting to our institution were evaluated by an ECG followed by a 24‐h Holter. QTc measurement on both platforms using Bazett and Fridericia formulae was recorded and compared.

Results

Mean age was 14.09 years, with the majority being males. Mean heart rate was 125.87. In the ECG, the mean QTc interval via the Bazett formula was 0.40 s compared with 0.38 s using the Fridericia formula. The mean corrected QT via the Bazett formula was 0.45, 0.39, and 0.42 s for the shortest RR, the longest RR, and the average RR, respectively. In contrast to the Fridericia formula, the corrected QT interval was 0.40, 0.39, and 0.40 s for the shortest RR, the longest RR, and the average RR, respectively. Using the Bazett formula, the highest specificity was reached during the longest RR interval (92.2%), while the highest sensitivity was recorded during the shortest RR interval (40%). As for the Fridericiaformula, sensitivity always reached 0%, while the highest specificity was reached during the average RR interval.

Conclusion

QTc measured during Holter ECG reached a high specificity regardless of RR interval using the Fridericia and during the longest and the average RR interval for the Bazett formula. The consistently low sensitivity reveals that Holter ECG should not be used to rule out prolonged QT.

Pediatric Palliative Care Pharmacy Pearls—A Focus on Pain and Sedation

Determining the optimal dosing regimen for pediatric patients is a challenge due to the lack of dosing guidelines and studies. In addition, many developmental pharmacology changes that occur throughout childhood that have profound impacts on the absorption, distribution, metabolism, and elimination of medications are commonly used in palliative care. Adding to that complexity, certain medications have different effects in the pediatric patient compared to the adult patient. Being aware of the pharmacokinetic changes, impact on neurodevelopment and unique medication factors that are present in pediatric patients helps clinicians treat the pediatric palliative care patient in the best and safest way possible.

Association between exposure to Efavirenz and substrates of dysrhythmia in HIV-infected young adults

Background

Dysrhythmia and sudden cardiac arrest occur more likely in HIV patients than healthy subjects. Thus, we need to examine dysrhythmias adverse effects of medications including Efavirenz as early as possible especially in young subjects.

Hypothesis

Efavirenz might have contributed to increased risk of developing common types of dysrhythmia in young HIV infected patients.

Methods

We performed a retrospective cohort study among 62 patients on Efavirenz and 38 controls. All participants were under 40 years old without cardiovascular disease. Total significant dysrhythmia in 24‐hour ECG monitoring was the primary endpoint determined as the composite of high premature ventricular contraction (PVC) (>500 beats per 24 hours), high premature atrial contraction (PAC) (>500 bp24h), sinus pause, atrioventricular blocks, ventricular tachycardia, prolonged QTc, and low heart rate variability (HRV). Modified composite dysrhythmia consisted of low HRV (SD of normal‐to‐normal [SDNN]), high PVC and prolonged QT.

Results

Mean heart rate, Efavirenz regimen, male gender, and CD4 count predicted total dysrhythmia. Odds ratios were 1.108, 2.90, 4.36, and 0.96, respectively. The incidence of total dysrhythmia, high PVC, high PAC, low HRV(SDNN), and prolonged QTc were 54.8%, 41.85%, 9.71%, 45.2%, and 12.9% in patients on Efavirenz against 42.11%, 31.64%, 0%, 34.2%, and 7.91% in controls, respectively (p‐values: .031, .001, <.0001, .063, and .043 respectively). Modified composite dysrhythmia was also more frequent in Efavirenz group than that of control group (69.42% vs. 52.60%, respectively p = .032).

Conclusions

We found that patients with Efavirenz had higher prevalence of frequent PVC, frequent PAC, total significant dysrhythmia, Low HRV and prolonged QTc than controls.

Post hoc assessment of relationship between coronary stenosis, ECG and ventricular function in patients with heart disease

Cardiovascular diseases including cardiac arrhythmias lead to fatal events in patients with coronary artery disease, however clinical associations from echocardiography, electrocardiography (ECG) and biomarkers remain unknown. We sought to identify the factors that may be related to elevated QRS intervals in patients with risk for coronary artery disease. In this study, we performed analysis of clinical data from 503 patients and divided into two groups, i.e., patients with either <50% coronary artery stenosis or >50% coronary artery stenosis. We further examined patients with elevated ECG parameters such as QRS>100ms and QTc>440ms. Patients with >50% coronary artery stenosis exhibited significant increases in age, triglycerides, and troponin levels. Further, ECG parameters demonstrated increased QRS and QTc durations, while echocardiographic parameters highlighted a decreased in ejection fraction (EF) and fractional shortening (FS). Patients with QTc>440ms exhibited increased Brain natriuretic peptide and Creatinine levels with a decrease in eGFR clearance rates. Patients with QRS>100ms had greater left ventricular (LV) mass, LV internal diameter in systole and diastole. Multimodal logistic regression showed significant relation between QTc, age and creatinine. These findings suggest that patients with significant coronary stenosis may have lower EF and FS with prolonged QRS intervals demonstrating greater risk for arrhythmic events.

Life-threatening complications of hyperemesis gravidarum

Hyperemesis gravidarum (HG) refers to severe nausea and emesis noted during pregnancy. However, no consensus exists on the specific diagnostic criteria that can be used for this condition. The aim of the present systematic review was to summarize the available evidence regarding the severe complications observed during HG with a heightened risk of fatality. A systematic search was conducted on PubMed, Cochrane Library, EMBASE and WILEY databases for the relevant publications regarding the severe and life-threatening complications of HG. The search terms were as follows: '(Hyperemesis gravidarum)' AND ('complications' OR 'severe' OR 'adverse pregnancy outcomes' OR 'stroke' OR 'seizures' OR 'Wernicke's encephalopathy' OR 'arrhythmias' OR 'pneumomediastinum' OR 'coagulopathy' OR 'electrolytic imbalance'). Abstracts, conference presentations, letters to the editor, studies written in languages other than English and editorials were all excluded. This search identified 43 studies analyzing life-threatening complications of HG, of which 11, seven, eight and 17 articles analyzed neurological, cardiovascular, thoracic and systemic complications, respectively. Reports on life-threatening complications were exceptionally rare in HG. The most frequent severe complications noted were Wernicke's encephalopathy, electrolyte imbalance and vitamin K deficiency. The low mortality rate for patients with HG over the last decade could be explained by the high efficiency of modern therapy, and the precise management of every complication according to current guidelines.

Pediatric athletes' ECG and diagnostic performance of contemporary ECG interpretation criteria

BACKGROUND

Electrocardiographic (ECG) pre-participation screening(PPS) can prevent sudden cardiac death(SCD) but the Interpretation of the athlete's ECG is based on specific criteria addressed for adult athletes while few data exist about the pediatric athlete's ECG. We aimed to assess the features of pediatric athletes' ECG and compared the diagnostic performance of 2017 International ECG recommendation, 2010 European Society of Cardiology recommendation and 2013-Seattle criteria in detecting clinical conditions at risk of SCD.

METHODS

886 consecutive pediatric athletes (mean age 11.7 ± 2.5 years; 7-16-years) were enrolled and prospectively evaluated with medical history, physical examination, resting and exercise ECG and transthoracic echocardiography during their PPS.

RESULTS

The most common physiological ECG patterns in pediatric athletes were isolated left ventricular hypertrophy criteria (26.9%), juvenile T-wave pattern (22%) and early repolarization pattern (13.2%). The most frequent borderline abnormalities were left axis deviation (1.8%) and right axis deviation (0.9%) while T-wave inversion (0.8%) especially located in inferior leads (0.7%) was the most prevalent abnormal findings. Seven athletes (0.79%) were diagnosed with a condition related to SCD. Compared to Seattle and ESC, the International improved ECG specificity (International = 98% ESC = 64% Seattle = 95%) with lower sensitivity (ESC and Seattle 86%vs International 57%). The false-positive rate decreases from 36% of ESC to 2.2% of International but the latter showed a higher false-negative rate(0.34%).

CONCLUSION

Pediatric athletes like the adult counterpart exhibit a high prevalence of ECG abnormalities mostly representing training-related ECG adaptation. The International criteria showed a lower false-positive rate but at the cost of loss of sensitivity.

Effect of Memantine on QT/QTc Interval in a Healthy Korean Population

Studies on the effects of memantine on QT prolongation have yielded conflicting results. For a long time, memantine was reported to be a safe drug without QT prolongation; however, several case studies have reported memantine-induced QT prolongation in Alzheimer's patients. This study evaluated the relationship between memantine blood levels, and QT interval changes. Over a 2-week period, we orally administered 20 mg of memantine daily to achieve a steady state in 57 healthy Korean subjects. We measured and analyzed the QT interval and blood memantine concentrations simultaneously before and after treatment, as well as 2 weeks after the last dosing. Correlation analysis was done between blood memantine level and QT interval. No serious adverse events occurred during the study period. Repeated dosing of memantine did not show clinically significant QT interval changes after treatment. Regression analysis was performed based on the results; there was no statistical association between memantine blood level and QT prolongation. In conclusion, the results of the present study demonstrated no clinically significant changes in the QT interval with therapeutic blood levels of memantine.

Human biventricular electromechanical simulations on the progression of electrocardiographic and mechanical abnormalities in post-myocardial infarction

AIMS

Develop, calibrate and evaluate with clinical data a human electromechanical modelling and simulation framework for multiscale, mechanistic investigations in healthy and post-myocardial infarction (MI) conditions, from ionic to clinical biomarkers.

METHODS AND RESULTS

Human healthy and post-MI electromechanical simulations were conducted with a novel biventricular model, calibrated and evaluated with experimental and clinical data, including torso/biventricular anatomy from clinical magnetic resonance, state-of-the-art human-based membrane kinetics, excitation-contraction and active tension models, and orthotropic electromechanical coupling. Electromechanical remodelling of the infarct/ischaemic region and the border zone were simulated for ischaemic, acute, and chronic states in a fully transmural anterior infarct and a subendocardial anterior infarct. The results were compared with clinical electrocardiogram and left ventricular ejection fraction (LVEF) data at similar states. Healthy model simulations show LVEF 63%, with 11% peak systolic wall thickening, QRS duration and QT interval of 100 ms and 330 ms. LVEF in ischaemic, acute, and chronic post-MI states were 56%, 51%, and 52%, respectively. In linking the three post-MI simulations, it was apparent that elevated resting potential due to hyperkalaemia in the infarcted region led to ST-segment elevation, while a large repolarization gradient corresponded to T-wave inversion. Mechanically, the chronic stiffening of the infarct region had the benefit of improving systolic function by reducing infarct bulging at the expense of reducing diastolic function by inhibiting inflation.

CONCLUSION

Our human-based multiscale modelling and simulation framework enables mechanistic investigations into patho-physiological electrophysiological and mechanical behaviour and can serve as testbed to guide the optimization of pharmacological and electrical therapies.

Opium-associated QT Interval Prolongation: A Cross-sectional Comparative Study

Background

Toxicity and side effects of long-term use of opioids are well studied, but little information exists regarding electrophysiological disturbances of opium consumption. While natural opium has been regarded safe to a great extent among traditional communities, concerns are emerging owing to the available evidence of QT prolongation that have been exposed during recent outcome surveillance of patients under opioid use. Potential QT prolonging interactions would raise a higher level of such concern in opium users during COVID pandemic and warrant attention.

Materials and methods

This study was designed to detect the prevalence of QTc prolongation among opium users and nonusers. Two groups were compared with regard to gender, age, and median QTc interval. Normal and prolonged QTc intervals of user group were compared with respect to age, sex, dose of opium consumption, and duration of opium consumption.

Results

123 opium users and 39 controls were investigated. Median QTc interval in opium user and non-user group was 460 vs 386 milliseconds, respectively (p value < 0.001). In all, 59.3%, (95% CI: 50.51–67.62%) of cases and none of non-user had prolonged QTc interval (p value < 0.001). There was no significance between normal and prolonged QTc intervals with respect to dose and duration of opium use.

Conclusion

This study indicated that opium consumption is associated with QTc prolongation. This prolongation does not relate to dose and duration of opium use. Further study is propounded to assess the clinical significance of these results and to determine risk rating of opium compared to other opioids in this regard.

How to cite this article

Javadi HR, Mirakbari SM, Allami A, Yazdi Z, Katebi K. Opium-associated QT Interval Prolongation: A Cross-sectional Comparative Study. Indian J Crit Care Med 2021;25(1):43–47.

Problems with Bazett QTc correction in paediatric screening of prolonged QTc interval

Background

Bazett formula is frequently used in paediatric screening for the long QT syndrome (LQTS) and proposals exist that using standing rather than supine electrocardiograms (ECG) improves the sensitivity of LQTS diagnosis. Nevertheless, compared to adults, children have higher heart rates (especially during postural provocations) and Bazett correction is also known to lead to artificially prolonged QTc values at increased heart rates. This study assessed the incidence of erroneously increased QTc values in normal children without QT abnormalities.

Methods

Continuous 12-lead ECGs were recorded in 332 healthy children (166 girls) aged 10.7 ± 2.6 years while they performed postural manoeuvring consisting of episodes (in the following order) of supine, sitting, standing, supine, standing, sitting, and supine positions, each lasting 10 min. Detailed analyses of QT/RR profiles confirmed the absence of prolonged individually corrected QTc interval in each child. Heart rate and QT intervals were measured in 10-s ECG segments and in each segment, QTc intervals were obtained using Bazett, Fridericia, and Framingham formulas. In each child, the heart rates and QTc values obtained during supine, sitting and standing positions were averaged. QTc durations by the three formulas were classified to < 440 ms, 440–460 ms, 460–480 ms, and > 480 ms.

Results

At supine position, averaged heart rate was 77.5 ± 10.5 beat per minute (bpm) and Bazett, Fridericia and Framingham QTc intervals were 425.3 ± 15.8, 407.8 ± 13.9, and 408.2 ± 13.1 ms, respectively. At sitting and standing, averaged heart rate increased to 90.9 ± 10.1 and 100.9 ± 10.5 bpm, respectively. While Fridericia and Framingham formulas showed only minimal QTc changes, Bazett correction led to QTc increases to 435 ± 15.1 and 444.9 ± 15.9 ms at sitting and standing, respectively. At sitting, Bazett correction identified 51, 4, and 0 children as having the QTc intervals 440–460, 460–480, and > 480 ms, respectively. At sitting, these numbers increased to 118, 11, and 1, while on standing these numbers were 151, 45, and 5, respectively. Irrespective of the postural position, Fridericia and Framingham formulas identified only a small number (< 7) of children with QT interval between 440 and 460 ms and no children with longer QTc.

Conclusion

During screening for LQTS in children, the use of Bazett formula leads to a high number of false positive cases especially if the heart rates are increased (e.g. by postural manoeuvring). The use of Fridericia formula can be recommended to replace the Bazett correction not only for adult but also for paediatric ECGs.

Acquired long QT syndrome in chronic kidney disease patients

Cardiovascular disease (CVD) is the leading cause of morbidity and mortality in chronic kidney disease (CKD) patients. QT interval prolongation is a congenital or acquired condition that is associated with an increased risk of torsade de pointes (TdP), sudden cardiac death (SCD), and all-cause mortality in the general population. The prevalence of acquired long QT syndrome (aLQTS) is high, and various acquired conditions contribute to the prolonged QT interval in patients with CKD. More notably, the prolonged QT interval in CKD is an independent risk factor for SCD and all-cause mortality. In this review, we focus on the epidemiological characteristics, risk factors, underlying mechanisms and treatments of aLQTS in CKD, promoting the management of aLQTS in CKD patients.

Plasma methylcitric acid and its correlations with other disease biomarkers: The impact in the follow up of patients with propionic and methylmalonic acidemia

Methylcitric acid (MCA) analysis has been mainly utilized for the diagnosis of propionate disorders or as a second-tier test in newborn screening, but its utility for patients monitoring still needs to be established. We explored the potential contribution of MCA in the long-term management of organic acidurias. We prospectively evaluated plasma MCA and its relationship with disease biomarkers, clinical status, and disease burden in 22 patients, 13 with propionic acidemia (PA) and nine with methylmalonic acidemia (MMA) on standard treatment and/or after transplantation. Samples were collected at scheduled routine controls or during episodes of metabolic decompensation (MD), 10 patients were evaluated after transplantation (six liver, two combined liver and kidney, 2 kidney). MCA levels were higher in PA compared to MMA and its levels were not influenced by the clinical status (MD vs well state). In MMA, MCA was higher in elder patients and, along with fibroblast growth factor 21 (FGF21) and plasma methylmalonic acid, negatively correlated with GFR. In both diseases, MCA correlated with ammonia, glycine, lysine, C3, and the C3/C2, C3/C16 ratios. The disease burden showed a direct correlation with MCA and FGF21, for both diseases. All transplanted patients showed a significant reduction of MCA in comparison to baseline values, with some differences dependent on the type of transplantation. Our study provided new insights in understanding the disease pathophysiology, showing similarities between MCA and FGF21 in predicting disease burden, long-term complications and in evaluating the impact of organ transplantation.

Automatic identification of a stable QRST complex for non-invasive evaluation of human cardiac electrophysiology

BACKGROUND

A vectorcardiography approach to electrocardiology contributes to the non-invasive assessment of electrical heterogeneity in the ventricles of the heart and to risk stratification for cardiac events including sudden cardiac death. The aim of this study was to develop an automatic method that identifies a representative QRST complex (QRSonset to Tend) from a Frank vectorcardiogram (VCG). This method should provide reliable measurements of morphological VCG parameters and signal when such measurements required manual scrutiny.

METHODS

Frank VCG was recorded in a population-based sample of 1094 participants (550 women) 50-65 years old as part of the Swedish CArdioPulmonary bioImage Study (SCAPIS) pilot. Standardized supine rest allowing heart rate stabilization and adaptation of ventricular repolarization preceded a recording period lasting ≥5 minutes. In the Frank VCG a recording segment during steady-state conditions and with good signal quality was selected based on QRST variability. In this segment a representative signal-averaged QRST complex from cardiac cycles during 10s was selected. Twenty-eight morphological parameters were calculated including both conventional conduction intervals and VCG-derived parameters. The reliability and reproducibility of these parameters were evaluated when using completely automatic and automatic but manually edited annotation points.

RESULTS

In 1080 participants (98.7%) our automatic method reliably selected a representative QRST complex where its instability measure effectively identified signal variability due to both external disturbances ("noise") and physiologic and pathophysiologic variability, such as e.g. sinus arrhythmia and atrial fibrillation. There were significant sex-related differences in 24 of 28 VCG parameters. Some VCG parameters were insensitive to the instability value, while others were moderately sensitive.

CONCLUSION

We developed an automatic process for identification of a signal-averaged QRST complex suitable for morphologic measurements which worked reliably in 99% of participants. This process is applicable for all non-invasive analyses of cardiac electrophysiology including risk stratification for cardiac death based on such measurements.

Electrocardiographic findings of methanol toxicity: a cross-sectional study of 356 cases in Iran

BACKGROUND

Methanol is widely used in industry; however, methanol poisoning is not common. In this regard, a number of outbreaks have been recently reported due to inappropriate processing of alcoholic beverages. Shiraz, a city located in the southern part of Iran, faced one of such outbreaks in 2020 during COVID-19 pandemic. There is no sufficient literature on the electrocardiographic findings in methanol toxicity. This study aimed to address this gap in the literature.

METHOD

A total of 356 cases with methanol toxicity referred to Shiraz University of Medical Science Tertiary Hospitals (Faghihi and Namazi) in March and April, 2020. The clinical findings of blindness and impaired level of consciousness, lab data such as arterial blood gas, electrolytes, and creatinine, and the most common findings from ECGs were collected.

RESULTS

The most common ECG findings were J point elevation (68.8%), presence of U wave (59.2%), QTc prolongation (53.2% in males and 28.6% in females), and fragmented QRS (33.7%). An outstanding finding in this study was the presence of myocardial infarction in 5.3% of the cases. This finding, to the best of our knowledge, has only been reported in a few case reports. Brugada pattern (8.1%) and Osborn wave (3.7%) were the other interesting findings. In multivariate analysis, when confounding factors were adjusted, myocardial infarction, atrioventricular conduction disturbances, sinus tachycardia, and the prolonged QTC > 500 msecond were four independent factors correlated with methanol toxicity severity measured with arterial blood PH on arterial blood gas measurements, with odds ratios of 12.82, 4.46, 2.32 and 3.15 (P < 0.05 for all), respectively.

CONCLUSION

Electrocardiographic variations during methanol intoxication are remarkable and well-correlated with poisoning severity. Myocardial infarction was an egregious and yet a common concerning finding in this sample, which need to be ruled out in methanol toxicity.