Electrocardiographic T Wave Abnormalities and the Risk of Sudden Cardiac Death: The Finnish Perspective

Exploration of Clozapine-Induced Cardiomyopathy and Its Mechanism

In this study, by pooling the clinical data of patients who died with a history of long-term clozapine use and by examining their hearts, it was found that long-term clozapine use can lead to cardiomyopathy and that its presentation resembles arrhythmogenic cardiomyopathy (ACM), i.e., it exhibits a predominantly right ventricular fatty infiltration with mild left ventricular damage. The transcriptomic data of rat cardiomyocytes after clozapine intervention were analyzed by transcriptomic approach to explore the causes of clozapine cardiomyopathy. The cause of clozapine cardiomyopathy was then explored by a transcriptomic approach, which revealed that its clozapine action on cardiomyocytes enriched cardiomyocyte-related differential genes in biological processes such as muscle development and response to hypoxia, as well as pathways such as fatty acid metabolism and cellular autophagy. Transcriptomic analysis showed that Egr1, Egr2, ler2, Jun, Mapk9, Nr1d2, Atf3, Bhlhe40, Crem, Cry1, Cry2, Dbp were hub genes for clozapine injury to the myocardium, and that these genes may play an important role in the myocardial ACM-like changes caused by clozapine. Combined with the results of pathological examination and transcriptomic analysis, it can be concluded that the long-term action of clozapine on cardiomyocytes leads to cellular autophagy and subsequent structural remodeling of the heart, and in the remodeling affects fatty acid metabolism, which eventually leads to ACM-like changes.

Greater Disease Severity and Worse Clinical Outcomes in Patients Hospitalised with COVID-19 in Africa

Background

COVID-19 cardiovascular research from Africa is limited. This study describes cardiovascular risk factors, manifestations, and outcomes of patients hospitalised with COVID-19 in the African region, with an overarching goal to investigate whether important differences exist between African and other populations, which may inform health policies.

Methods

A multinational prospective cohort study was conducted on adults hospitalised with confirmed COVID-19, consecutively admitted to 40 hospitals across 23 countries, 6 of which were African countries. Of the 5,313 participants enrolled globally, 948 were from African sites (n = 9). Data on demographics, pre-existing conditions, clinical outcomes in hospital (major adverse cardiovascular events (MACE), renal failure, neurological events, pulmonary outcomes, and death), 30-day vitality status and re-hospitalization were assessed, comparing African to non-African participants.

Results

Access to specialist care at African sites was significantly lower than the global average (71% vs. 95%), as were ICU admissions (19.4% vs. 34.0%) and COVID-19 vaccination rates (0.6% vs. 7.4%). The African cohort was slightly younger than the non-African cohort (55.0 vs. 57.5 years), with higher rates of hypertension (48.8% vs. 46.9%), HIV (5.9% vs. 0.3%), and Tuberculosis (3.6% vs. 0.3%). In African sites, a higher proportion of patients suffered cardiac arrest (7.5% vs. 5.1%) and acute kidney injury (12.7% vs. 7.2%), with acute kidney injury (AKI) appearing to be one of the strongest predictors of MACE and death in African populations compared to other populations. The overall mortality rate was significantly higher among African participants (18.2% vs. 14.2%).

Conclusions

Overall, hospitalised African patients with COVID-19 had a higher mortality despite a lower mean age, contradicting literature that had previously reported a lower mortality attributed to COVID-19 in Africa. African sites had lower COVID-19 vaccination rates and higher AKI rates, which were positively associated with increased mortality. In conclusion, African patients were hospitalized with more severe COVID-19 cases and had poorer outcomes.

Speckle tracking echocardiography for diagnosis of right ventricular failure in children with totally corrected tetralogy of Fallot in Sulaimani, Iraq

Objectives

The study was aimed at using speckle tracking echocardiography as a novel technique to diagnose right ventricular failure (RVF) in children with total correction of tetralogy of Fallot (TOF) through surgery.

Methods

A quasi-experimental study was performed at the Children's Heart Hospital of Sulaimani for 9 months. A total of 150 children with completely repaired TOF were enrolled to investigate RVF. Conventional echocardiographic data were recorded, including right ventricular (RV) ejection fraction (EF), tricuspid annular plane systolic excursion (TAPSE), myocardial performance index (MPI), and RV end-systolic and diastolic volume (RVESV and RVEDV). Additionally, speckle tracking was performed for the regional and longitudinal strain and strain rate in four-chamber apical view. RVF diagnosis was determined on the basis of electrocardiography measurement of P-wave dispersion, T-wave dispersion, and QRS duration.

Results

Children with repaired TOF who were diagnosed with RVF through conventional echocardiography exhibited abnormalities with respect to children with normal RV function, including a TAPSE of 1.3 ± 0.11 cm, RVEF of 35.5 ± 6.72, RVESV of 69.8 ± 15.13 ml, RVEDV of 110.1 ± 14.13 ml, MPI of 0.60 ± 0.12, and Pmax of 52.4 ± 14.08. The use of speckle tracking in RVF diagnosis revealed a relatively lower longitudinal strain and strain rate (-12.1 ± 2.3 and -0.9 ± 0.3, respectively) in the children with RVF. Moreover, longitudinal right ventricular strain was positively correlated with TAPSE (r = 0.656) and EF (r = 0.675), and negatively correlated with RVEDV (r = -0.684), RVESV (r = -0.718), MPI (r = -0.735), and Pmax (r = -0.767).

Conclusions

The application of speckle tracking with the longitudinal RV strain and strain rate to estimate RV function in children with repaired TOF is a new advanced method that, compared with conventional echo, significantly improves the diagnosis of regional myocardial deformations and cardiac muscle motion velocity.

Fibroblast growth factor 21 is associated with widening QRS complex and prolonged corrected QT interval in patients with stable angina

BACKGROUND

Fibroblast growth factor 21 (FGF21) is produced by cardiac cells, may acts in an autocrine manner, and was suggested to has a cardioprotective role in atherosclerosis. Wide QRS complex and heart rate-corrected QT interval (QTc interval) prolongation are associated to dangerous ventricular arrhythmias and cardiovascular disease mortality. Yet, the role of FGF21 in cardiac arrhythmia has never been studied. The aim of the study was to investigate the relationship between plasma FGF21 and the QRS duration and QTc interval in patients with stable angina.

METHODS

Three hundred twenty-one consecutive stable angina patients were investigated. Plasma FGF21 was measured through ELISA, and each subject underwent 12-lead electrocardiography.

RESULTS

FGF21 plasma levels were positively associated with the QRS duration (β = 0.190, P = 0.001) and QTc interval (β = 0.277, P < 0.0001). With increasing FGF21 tertiles, the patients had higher frequencies of wide QRS complex and prolonged QTc interval. After adjusting for patients' anthropometric parameters, the corresponding odd ratios (ORs) for wide QRS complex of the medium and high of FGF21 versus the low of FGF21 were 1.39 (95% CI 0.51-3.90) and 4.41 (95% CI 1.84-11.59), respectively, and p for trend was 0.001. Furthermore, multiple logistic regression analysis also showed the corresponding odd ratios (ORs) for prolonged QTc interval of the medium and high of FGF21 versus the low of FGF21 were 1.02 (95% CI 0.53-1.78) and 1.93 (95% CI 1.04-3.60) respectively with the p for trend of 0.037. In addition, age- and sex-adjusted FGF21 levels were positively associated with fasting glucose, HbA1c, creatinine, and adiponectin, but negatively associated with albumin, and the estimated glomerular filtration rate.

CONCLUSIONS

This study indicates that plasma FGF21 is associated with wide QRS complex and prolonged corrected QT interval in stable angina patients, further study is required to investigate the role of plasma FGF21 for the underlying pathogenesis.

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.

Nonspecific ventricular repolarization abnormalities: A wolf in sheep's clothing

The term nonspecific ventricular repolarization abnormalities refers to a set of minor alterations of the ST segment and/or the T wave. For a long time, they have been of little clinical interest as they do not translate into specific diagnoses. It has even been asserted that they constitute benign electrocardiographic findings. Their presence has been reported in various cardiovascular and non-cardiovascular diseases. However, it is frequently identified in apparently healthy asymptomatic people. A growing number of studies demonstrate their importance as predictors of cardiovascular morbidity and mortality, expanding their spectrum towards cardiovascular prevention. In light of the body of scientific evidence, it is imperative that the traditional view of nonspecific ventricular repolarization abnormalities changes.

Combined Effects of Age and Comorbidities on Electrocardiographic Parameters in a Large Non-Selected Population

Background: Previous studies have evaluated average electrocardiographic (ECG) values in healthy subjects or specific subpopulations. However, none have evaluated ECG average values in not selected populations, so we examined ECG changes with respect to age and sex in a large primary population. Methods: From digitized ECG stored from 2008 to 2021 in the Modena province, 130,471 patients were enrolled. Heart rate, P, QRS and T wave axis, P, QRS and T wave duration, PR interval, QTc, and frontal QRS-T angle were evaluated. Results: All ECG parameters showed a dependence on age, but only some of them with a straight-line correlation: QRS axis (p < 0.001, R2 = 0.991, r = 0.996), PR interval (p < 0.001, R2 = 0.978, r = 0.989), QTc (p < 0.001, R2 = 0.935, r = 0.967), and, in over 51.5 years old, QRS-T angle (p < 0.001, R2 = 0.979, r = 0.956). Differences between females and males and in different clinical settings were observed. Conclusions: ECG changes with ageing are explainable by intrinsic modifications of the heart and thorax and with the appearance of cardiovascular diseases and comorbidities. Age-related reference values were computed and applicable in clinical practice. Significant deviations from mean values and from Z-scores should be investigated.

Predictive value of electrocardiographic markers in children with dilated cardiomyopathy

Dilated cardiomyopathy (DCM) refers to a heterogeneous group of cardiomyopathies characterized by ventricular dilatation and myocardial systolic dysfunction, which can lead to serious consequences such as malign arrhythmia, sudden death, heart failure, and thromboembolism. With its economical, non-invasive, simple and reproducible advantages, electrocardiogram (ECG) has become an important indicator for assessing the prognosis of cardiovascular diseases. In recent years, more and more studies of electrocardiography on DCM have been carried out, but there is still a lack of a comprehensive summary of its prognostic value. This article reviews the prognostic value of electrocardiographic markers in children with DCM.

Interleukin-6 expression and its modulation by diacerein in a rat model of chronic stress induced cardiac dysfunction

People with chronic stress have higher levels of pro-inflammatory cytokines, which enhance their susceptibility to cardiovascular diseases. Diacerein has ability to modulate pro-inflammatory cytokines such as IL-1β and IL-6; however, its efficacy in chronic stress associated cardiovascular diseases is not yet assessed. In this study, we standardized a rat model of chronic unpredictable stress (CUS) demonstrating cardiovascular dysfunctions and further assessed the effect of IL-6 modulator, diacerein, on cardiovascular functions in CUS exposed rats. The CUS procedure consisted of exposing male albino Wistar rats to random stressors, everyday for 8 weeks. The binding affinity of diacerein with IL-6 was ascertained using Docking tools viz AutoDock and SwissDock. Moreover, diacerein was administered (50 mg/kg/day x 20 days P.O) post CUS exposure to rats and the serum IL-6 levels and heart functions of CUS rats were determined by ELISA and ECG-HRV analysis, respectively. 8 weeks of CUS exposure resulted in two-fold increase in serum corticosterone and IL-6 levels in rats. The ECG and HRV analysis of CUS rats showed altered sinus rhythm, elevated heart rate, systolic blood pressure and sympathetic tone. Molecular docking studies revealed diacerein high binding affinity towards IL-6 receptor. The post-treatment of diacerein in CUS rats prevented these cardiovascular dysfunctions. Our findings thus suggests that IL-6 may have a prominent role in chronic stress induced cardiovascular dysfunctions and diacerein, could be used as a preventive measure for such conditions.

Prognostic significance of flat T-waves in the lateral leads in general population

BACKGROUND

Negative T-waves are associated with sudden cardiac death (SCD) risk in the general population. Whether flat T-waves also predict SCD is not known. The aim of the study was to examine the clinical characteristics and risk of SCD in general population subjects with flat T-waves.

METHODS

We examined the electrocardiograms of 6750 Finnish general population adults aged ≥30 years and classified the subjects into 3 groups: 1) negative T-waves with an amplitude ≥0.1 mV in ≥2 of the leads I, II, aVL, V4-V6, 2) negative or positive low amplitude T-waves with an amplitude <0.1 mV and the ratio of T-wave and R-wave <10% in ≥2 of the leads I, II, aVL, V4-V6, and 3) normal positive T-waves (not meeting the aforesaid criteria). The association between T-wave classification and SCD was assessed during a 10-year follow-up.

RESULTS

A total of 215 (3.2%) subjects had negative T-waves, 856 (12.7%) flat T-waves, and 5679 (84.1%) normal T-waves. Flat T-wave subjects were older and had more often cardiovascular morbidities compared to normal T-wave subjects, while negative T-wave subjects were the oldest and had most often cardiovascular morbidities. After adjusting for multiple factors, both flat T-waves (hazard ratio [HR] 1.81; 95% confidence interval [CI] 1.13-2.91) and negative T-waves (HR 3.27; 95% CI 1.85-5.78) associated with SCD.

CONCLUSIONS

Cardiovascular risk factors and disease are common among subjects with flat T-waves, but these minor T-wave abnormalities are also independently associated with increased SCD risk.

The Changes of T-Wave Amplitude and QT Interval Between the Supine and Orthostatic Electrocardiogram in Children With Dilated Cardiomyopathy

Objectives: Electrocardiogram (ECG) can be affected by autonomic nerves with body position changes. The study aims to explore the ECG changes of children with dilated cardiomyopathy (DCM) when their posture changes. Materials and methods: Sixty-four children diagnosed with DCM were recruited as research group and 55 healthy children as control group. T-wave amplitude and QT interval in ECG were recorded, and their differences between supine and orthostatic ECG were compared in both groups. Subsequently, the children with DCM were followed up and the differences before and after treatment compared. Results: ① Comparisons in differences: Differences of T-wave amplitude in lead II and III, aVF, and V₅ and differences of QT interval in lead II, aVL, aVF, and V₅ were lower in the research group than in the control group. ② Logistic regression analysis and diagnostic test evaluation: The differences of T-wave amplitude in lead III and QT interval in lead aVL may have predictive value for DCM diagnosis. When their values were 0.00 mV and 30 ms, respectively, the sensitivity and specificity of the combined index were 37.5 and 83.6%. ③ Follow-up: In the response group, the T-wave amplitude difference in lead aVR increased and the difference of QT interval in lead V₆ decreased after treatment. In the non-response group, there was no difference before and after treatment. When the combined index of the differences of T-wave amplitude difference in lead aVR and QT interval difference in lead V₆, respectively, were -0.05 mV and 5 ms, the sensitivity and specificity of estimating the prognosis of DCM were 44.4 and 83.3%. Conclusions: The differences of T-wave amplitude and QT interval may have a certain value to estimate DCM diagnosis and prognosis.

[Association of T-wave amplitude on electrocardiogram with left ventricular ejection fraction in children with dilated cardiomyopathy]

OBJECTIVE

To study the association of T-wave amplitude on electrocardiogram (ECG) with left ventricular ejection fraction (LVEF) in children with dilated cardiomyopathy.

METHODS

A retrospective analysis was performed for the clinical data of 44 children who were diagnosed with dilated cardiomyopathy from May 2009 to June 2018. According to LVEF, they were divided into two groups: LVEF ≥50% group (n=26) and LVEF <50% group (n=18). After treatment, 25 children were followed up for 3-42 months (mean 14±9 months). The Guangdong Zhongshan SR-1000A ECG Automatic Analyzer was used to obtain the 12-lead body surface ECG results in the supine position. T-wave amplitude on ECG was evaluated by software and manual measurement.

RESULTS

Compared with the LVEF ≥50% group, the LVEF <50% group had a significant reduction in the T-wave amplitude in leads II, V4, V5 and V6 (P<0.05). The increased-LVEF group (an increase in LVEF > 5% after treatment) had a significant increase in the T-wave amplitude in leads aVR, V5, and V6 after treatment (P<0.05), while the unchanged-LVEF group (an increase in LVEF ≤ 5% after treatment) had a significant reduction in the T-wave amplitude in lead aVR after treatment (P<0.05). The receiver operating characteristic curve analysis showed that the T-wave amplitude in leads II, V4, V5 and V6 had a certain value in predicting LVEF <50% in children with dilated cardiomyopathy (P<0.05). A combination of T-wave amplitude of ≤0.20 mV in lead II, ≤0.40 mV in lead V4, and ≤0.30 mV in leads V5 and V6 had a sensitivity of 88.2% and specificity of 76.0% in the predication of LVEF <50% in children with dilated cardiomyopathy.

CONCLUSIONS

T-wave amplitude on ECG can be used as the indexes for the evaluation of the left ventricular systolic function in children with dilated cardiomyopathy.

An Improved Sliding Window Area Method for T Wave Detection

BACKGROUND

The T wave represents ECG repolarization, whose detection is required during myocardial ischemia, and the first significant change in the ECG signal is being observed in the ST segment followed by changes in other waves like P wave and QRS complex. To offer guidance in clinical diagnosis, decision-making, and daily mobile ECG monitoring, the T wave needs to be detected firstly. Recently, the sliding area-based method has received an increasing amount of attention due to its robustness and low computational burden. However, the parameter setting of the search window's boundaries in this method is not adaptive. Therefore, in this study, we proposed an improved sliding window area method with more adaptive parameter setting for T wave detection.

METHODS

Firstly, k-means clustering was used in the annotated MIT QT database to generate three piecewise functions for delineating the relationship between the RR interval and the interval from the R peak to the T wave onset and that between the RR interval and the interval from the R peak to the T wave offset. Then, the grid search technique combined with 5-fold cross validation was used to select the suitable parameters' combination for the sliding window area method.

RESULTS

With respect to onset detection in the QT database, F1 improved from 54.70% to 70.46% and 54.05% to 72.94% for the first and second electrocardiogram (ECG) channels, respectively. For offset detection, F1 also improved in both channels as it did in the European ST-T database.

CONCLUSIONS

F1 results from the improved algorithm version were higher than those from the traditional method, indicating a potentially useful application for the proposed method in ECG monitoring.

Evidence for cardiotoxicity associated with sertraline in rats

Sertraline is an antidepressant that is frequently prescribed to treat depression, obsessive-compulsive disorder, panic disorder, and anxiety. This drug had a safe cardiotoxicity profile, until the reporting of cases of sertraline-associated cardiotoxicities in the early 2000s. Since then, there have been conflicting results on the cardiotoxicity of this drug. In the study reported here we aimed to identify the cardiotoxic effects of sertraline by evaluating serum cardiac biomarkers, such as serum aspartate aminotransferase (AST), creatinine phosphokinase-myoglobin band (CK-MB), lactate dehydrogenase (LDH), and cardiac troponin T (cTn-T) levels as well as electrocardiographic parameters, DNA damage in cardiomyocytes, and histological findings of heart tissue in rats that were administered oral doses of 5, 10, or 20 mg kg-1 of sertraline for 28 days. Additionally, to investigate the possible mechanisms underlying cardiotoxicity, glutathione and malondialdehyde levels in cardiac tissue were determined to evaluate oxidative stress. According to our results, AST, LDH, and cTn-T levels were significantly increased in the 10 and 20 mg kg-1 sertraline groups when compared to the control group. Heart rates were increased, PR intervals prolonged, a short QTc value was observed, and T-wave amplitudes were decreased significantly in the 20 mg kg-1 sertraline group when compared to the control group. Significant DNA damage was observed in the high-dose groups. Histopathological investigations also revealed some degenerative changes in the 10 and 20 mg kg-1 sertraline groups. Glutathione levels were significantly decreased in the 10 and 20 mg kg-1 sertraline groups when compared with the control group. In conclusion, our findings support the cardiotoxic potential of sertraline and also suggest that oxidative stress may play a role in the toxicity of sertraline.

New approaches to predicting the risk of sudden death

In this review article, we will explore some of the contemporary methods for predicting sudden cardiac death (SCD). These include experimental methods yet to be adopted in the clinical setting, and methods that have been extrapolated from observational data in those with a history of SCD. We will discuss how these relate to the different aetiologies and disease processes. We will also explore how these may be used in the clinical setting to decide on management.