Relationships between the T-peak to T-end interval, ventricular tachyarrhythmia, and death in left ventricular systolic dysfunction

Epilepsy's effect on cardiac rhythm and the autonomic nervous system

OBJECTIVE

Sudden unexpected death in epilepsy is the most common cause of death in young patients with epilepsy. The aim of this study was to evaluate changes in interictal electrocardiogram parameters and sympathetic skin responses as markers of autonomic dysfunction in patients with epilepsy and to determine their effects on the type and duration of epilepsy, frequency of seizures, and responses to treatment.

METHODS

A total of 97 patients with epilepsy and 94 healthy controls were recruited. We recorded their clinical and demographic characteristics and analyzed sympathetic skin response latency and amplitude, electrocardiogram recordings, and seven cardiac rhythm parameters: P-wave duration, PR segment, QRS duration, QT interval, QT interval distribution, Tpe duration, and Tpe/QT interval ratio.

RESULTS

P-wave durations, T-wave durations, QT and QT interval durations, and Tpe and sympathetic skin response latency were significantly longer among patients with epilepsy than the controls, and their heart rate was significantly lower. However, sympathetic skin response latency and heart rate were negatively correlated, and T-wave duration, QT duration, QT interval duration, and Tpe were positively correlated.

CONCLUSION

Our results from interictal electrocardiograms indicate clinically significant arrhythmias among patients with epilepsy and the correlation of such arrhythmias with sympathetic skin responses. Thus, noninvasive tests that evaluate the autonomic system should be used to predict the risk of sudden unexpected death in epilepsy among patients with epilepsy.

Prognostic Value of Tpeak-Tend Interval in Early Diagnosis of Duchenne Muscular Dystrophy Cardiomyopathy

The most common cause of death in patients with Duchenne muscular dystrophy (DMD) is cardiomyopathy. Our aim was to investigate the relationship between the Tpeak-Tend (Tp-e) interval and the premature ventricular contraction (PVC) burden and therefore early arrhythmic risk and cardiac involvement in DMD patients. Twenty-five patients with DMD followed by pediatric cardiology were included in the study. Those with a frequency of <1% PVC in the 24 h Holter were assigned to Group 1 (n = 15), and those with >1% were assigned to Group 2 (n = 10). Comparisons were made with healthy controls (n = 27). Left ventricular ejection fraction (LVEF) was lowest in Group 2 and highest in the control group (p < 0.001). LV end-diastolic diameter was greater in Group 2 than in Group 1 and the control group (p = 0.005). Pro-BNP and troponin levels were higher in Group 1 and Group 2 than in the control group (p = 0.001 and p < 0.001, respectively). Tp-e interval was longer in Group 2 compared to Group 1 and the control group (p < 0.001). The LVEF (OR 0.879, 95% CI 0.812-0.953; p = 0.002) and Tp-e interval (OR 1.181, 95% CI 1.047-1.332; p = 0.007) were independent predictors of PVC/24 h frequency of >1%. A Tp-e interval > 71.65 ms predicts PVC > 1%, with a sensitivity of 80% and a specificity of 90% (AUC = 0.842, 95% CI (0.663-1.000), p = 0.001). Determination of Tp-e prolongation from ECG data may help in the determination of cardiac involvement and early diagnosis of arrhythmic risk in DMD.

A Longer Tpeak-Tend Interval Is Associated with a Higher Risk of Death: A Meta-Analysis

A noninvasive tool for cardiovascular risk stratification has not yet been established in the clinical routine analysis. Previous studies suggest a prolonged T_peak-T_end interval (the interval from the peak to the end of the T-wave) to be predictive of death. This meta-analysis was designed to systematically evaluate the association of the T_peak-T_end interval with mortality outcomes. Medline (via PubMed), Embase and the Cochrane Library were searched from 1 January 2008 to 21 July 2020 for articles reporting the ascertainment of the T_peak-T_end interval and observation of all-cause-mortality. The search yielded 1920 citations, of which 133 full-texts were retrieved and 29 observational studies involving 23,114 patients met the final criteria. All-cause deaths had longer T_peak-T_end intervals compared to survivors by a standardized mean difference of 0.41 (95% CI 0.23-0.58) and patients with a long T_peak-T_end interval had a higher risk of all-cause death compared to patients with a short T_peak-T_end interval by an overall odds ratio of 2.33 (95% CI 1.57-3.45). Heart rate correction, electrocardiographic (ECG) measurement methods and the selection of ECG leads were major sources of heterogeneity. Subgroup analyses revealed that heart rate correction did not affect the association of the T_peak-T_end interval with mortality outcomes, whereas this finding was not evident in all measurement methods. The T_peak-T_end interval was found to be significantly associated with all-cause mortality. Further studies are warranted to confirm the prognostic value of the T_peak-T_end interval.

The effect of ferric carboxymaltose treatment on the Tp-e interval and the Tp-e/QT and Tp-e/QTc ratios in heart failure patients with iron deficiency

Aim    In heart failure (HF) patients with iron deficiency, cardiac electrical irregularity is a cause of arrhythmias. The aim of our study was to evaluate the effect of ferric carboxymaltose (FCM) treatment on T wave peak to end (Tp-e) interval and the Tp-e / QT and Tp-e / corrected QT (QTc) ratios that reflect the transmural dispersion of repolarization in HF patients with iron deficiency.Material and methods    Forty HF patients with iron deficiency that were treated with FCM were included in our single center, observational study. Repolarization parameters on electrocardiograms recorded before and 12 wks after FCM treatment were compared. Additionally, these parameters were compared with ventricular repolarization parameters of 40 healthy age and gender matched individuals and with another group of 40 HF patients without iron deficiency.Results    In the HF patients with iron deficiency, the Tp-e interval and the Tp-e / QT and Tp-e / QTc ratios before FCM treatment were 103.7±19.1 ms, 0.25± 0.04, 0.23±0.04, respectively. These values were higher compared to the healthy the group and HF group without iron deficiency (p<0.001). In the HF patients with iron deficiency, the Tp-e interval and the Tp-e / QT and Tp-e / QTc ratios after FCM treatment were lower compared to pre-treatment and similar to the HF patients without iron deficiency (89.4±18.6 ms, 0.22±0.04, 0.20±0.04, respectively; p<0.001).Conclusion    FCM treatment of HF patients with iron deficiency corrects prolonged Tp-e interval and high Tp-e / QT and Tp-e / QTc ratios, which are risk factors for ventricular arrhythmias.

Arrhythmogenic Remodeling in the Failing Heart

Chronic heart failure is a clinical syndrome with multiple etiologies, associated with significant morbidity and mortality. Cardiac arrhythmias, including ventricular tachyarrhythmias and atrial fibrillation, are common in heart failure. A number of cardiac diseases including heart failure alter the expression and regulation of ion channels and transporters leading to arrhythmogenic electrical remodeling. Myocardial hypertrophy, fibrosis and scar formation are key elements of arrhythmogenic structural remodeling in heart failure. In this article, the mechanisms responsible for increased arrhythmia susceptibility as well as the underlying changes in ion channel, transporter expression and function as well as alterations in calcium handling in heart failure are discussed. Understanding the mechanisms of arrhythmogenic remodeling is key to improving arrhythmia management and the prevention of sudden cardiac death in patients with heart failure.

Clinical Associations between Serial Electrocardiography Measurements and Sudden Cardiac Death in Patients with End-Stage Renal Disease Undergoing Hemodialysis

The rate of sudden cardiac death (SCD) for hemodialysis (HD) patients is significantly higher than that observed in the general population and have the highest risk for arrhythmogenic death. In this multi-center study, patients starting hemodialysis in each hospital were enrolled; they underwent regular check-ups in an open-patient clinic. We examined serial electrocardiography (ECG) data in patients undergoing HD and determined their associations with the occurrence of SCD. Of 678 enrolled subjects who underwent serial ECG before and after hemodialysis, 291 died and 39 developed SCD. In all subjects, the QT peak-to-end (QTpe) interval at all leads and QRS duration were shortened after hemodialysis. The SCD group showed a significant change in the QTpe interval of the inferior, anterior, and lateral leads before and after hemodialysis compared with the survivor group (p < 0.001). In the pre-hemodialysis ECG, SCD patients had significantly longer QTpe intervals in all leads (p < 0.001) and a longer QRS duration (92.6 ± 14.0 vs. 100.6 ± 14.9 ms, p = 0.015) than survivors. In conclusion, patients with a longer QTpe interval before hemodialysis and large changes in ECG parameters after hemodialysis might be at a higher risk of SCD. Therefore, changes in the ECG before and after hemodialysis could help to predict SCD.

Cardiac arrhythmias and electrophysiologic responses during spontaneous hyperglycaemia in adults with type 1 diabetes mellitus

AIM

We examined the effect of spontaneous hyperglycaemia in adults with type 1 diabetes mellitus (T1DM) and without history of cardiovascular disease on heart rate variability (HRV), cardiac repolarisation and incidence of cardiac arrhythmias.

METHODS

Thirty-seven individuals with T1DM (age 17-50 years, 19 males, mean duration of diabetes 19.3 SD(9.6) years) underwent 96 h of simultaneous ambulatory 12-lead Holter ECG and blinded continuous interstitial glucose (IG) monitoring (CGM). HRV, QT interval and cardiac repolarisation were assessed during hyperglycaemia (IG ≥ 15 mmol/l) and compared with matched euglycaemia (IG 5-10 mmol/l) on a different day, separately during the day and night. Rates of arrhythmias were assessed by calculating incidence rate differences.

RESULTS

Simultaneous ECG and CGM data were recorded for 2395 hours. During daytime hyperglycaemia vs euglycaemia the mean QT_c interval duration was 404 SD(21)ms vs 407 SD(20)ms, P = 0.263. T-peak to T-end interval duration corrected for heart rate (T_pT_endc) shortened: 74.8 SD(16.1)ms vs 79.0 SD(14.8)ms, P = 0.033 and T-wave symmetry increased: 1.62 SD(0.33) vs 1.50 SD(0.39), P = 0.02. During night-time hyperglycaemia vs euglycaemia, the mean QT_c interval duration was 401 SD(26)ms vs 404 SD(27)ms, P = 0.13 and T_pT_end shortened: 62.4 SD(12.0)ms vs 67.1 SD(11.8)ms, P = 0.003. The number of cardiac arrhythmias was low and confined to bradycardia and isolated ectopic beats. A considerable inter-subject and diurnal variability was observed.

CONCLUSIONS

Hyperglycaemia in individuals with T1DM without known cardiovascular disease was not associated with clinically important cardiac arrhythmias.

The impact of fever on myocardial repolarization parameters

BACKGROUND

It has been reported in the literature that the increase in body temperature shortens QT interval on electrocardiogram through heart rate modulation. However, the effects of fever on ventricular repolarization are not clearly known. This study elaborates on QT interval of isolated fever, corrected QT (cQT), Tp-e interval, the ratio of corrected Tp-e (cTp-e) and Tp-e/QT, and their impacts on arrhythmia potential.

METHODS

This prospective study was performed on 74 patients without any active and chronic diseases other than fever and upper respiratory tract infection. The study included patients at the age of 18-50 years suffering from fever above 38.2 °C. QT and Tp-e intervals of the patients were measured from their ECGs taken in febrile and afebrile periods. cQT and cTp-e values were calculated according to Bazett, Fridericia, and Framingham formulations.

RESULTS

QT and Tp-e intervals were observed to be shorter in the febrile period (p < 0.001 and p = 0.006 respectively). cTp-e was found to be longer in the febrile period according to Bazett, Fridericia, and Framingham formulations (p < 0.001, p = 0.002, p < 0.001, respectively). Tp-e/QT ratio was found to be higher in the febrile period than in the afebrile period (p < 0.001).

CONCLUSION

Although QT, cQT, and Tpe intervals were shorter, cTpe interval and Tpe/QT ratio were longer and higher in the febrile period, respectively. These findings may indicate that fever may create a proarrhythmic effect by causing variability in the transmural distribution of myocardial repolarization.

No Association Between T-peak to T-end Interval on the Resting ECG and Long-Term Incidence of Ventricular Arrhythmias Triggering ICD Interventions

Background and Objectives

Potential of using the T-peak to T-end (TpTe) interval as an electrocardiographic parameter reflecting the transmural dispersion of ventricular repolarization (TDR) to identify patients (pts.) with higher risk of malignant ventricular arrhythmias (MVA) for better selection of candidates for implantable cardioverter-defibrillator (ICD) in primary prevention (PP) of sudden cardiac death (SCD) remains controversial. The primary objective of this study was to investigate the relationship between the TpTe interval in patient’s preimplantation resting 12-lead electrocardiogram (ECG) and the incidence of MVA resulting in appropriate ICD intervention (AI). The secondary objective was to assess its relationship to overall mortality.

Methods

A total of 243 consecutive pts. with severe left ventricular (LV) systolic dysfunction after myocardial infarction (MI) with a single-chamber ICD for PP of SCD from one implantation center were included. Excluded were all pts. with any other disease that could interfere with the indication of ICD implantation. Primarily investigated intervals were measured manually in accordance with accepted methodology. Data on ICD interventions were acquired from device interrogation during regular outpatient visits. Survival data were collected from the databases of health insurance and regulatory authorities.

Results

We did not find a significant relationship between the duration of the TpTe interval and the incidence of MVA (71.5 ms in pts. with MVA vs. 70 ms in pts. without MVA; p = 0.408). Similar results were obtained for the corrected TpTe interval (TpTec) and the ratio of TpTe to QT interval (76.3 ms vs. 76.5 ms; p = 0.539 and 0.178 vs. 0.181; p = 0.547, respectively). There was also no significant difference between the duration of TpTe, TpTec and TpTe/QT ratio in pts. groups by overall mortality (71.5 ms in the deceased group vs. 70 ms in the survivors group; HR 1.01; 95% CI, 0.99–1.02; p = 0.715, 76.3 ms vs. 76.5 ms; HR 1.01; 95% CI, 0.99–1.02; p = 0.208 and 0.178 vs. 0.186; p = 0.116, respectively).

Conclusion

This study suggests no significant association of overall or MVA-free survival with ECG parameters reflecting TDR (TpTe, TpTec) in patients with systolic dysfunction after MI and ICD implanted for primary prevention.

Correlation Between T Peak to End Interval and Left Ventricular Time to Peak Longitudinal Strain in Ischemic Cardiomyopathy Patients

Background

Ischemic cardiomyopathy is the most frequent etiology of heart failure with reduced ejection fraction (HFrEF) and a result of ventricular structural, functional and electrical remodeling. T peak to end (Tpe) interval is an electrocardiographic parameter that represents repolarization heterogeneity and had prognostic value for ventricular arrhythmia. Patients with ischemic cardiomyopathy face a significant burden of arrhythmias. Mechanical dispersion is a functional remodeling parameter that can be measured by time to peak longitudinal strain using speckle tracking echocardiography. This study aimed to assess the relationship between Tpe interval with time to peak longitudinal strain in ischemic cardiomyopathy patients.

Methods

This study was conducted with an observational analytical cross-sectional design. Ischemic cardiomyopathy subjects were included at Dr. Hasan Sadikin General Hospital, Bandung, from August to October 2019. Tpe interval was measured manually with the tangential method. Time to peak longitudinal strain was measured using speckle tracking echocardiography. The correlation between Tpe interval and time to peak longitudinal strain was analyzed using Pearson correlation.

Results

A total of 30 subjects were included in this study. The average age was 58 ± 8 years old, and the average left ventricular ejection fraction was 27±5.5%. The average of Tpe interval was 83.4 ± 7.62 ms, and the average time to peak longitudinal strain was 93.13 ± 34.51 ms. The Pearson correlation test showed a significant weak positive correlation (r = 0.386, 95% confidence interval: 0.029 - 0.743, P = 0.018) between Tpe interval and time to peak longitudinal strain in ischemic cardiomyopathy patients.

Conlucions

There was a significant weak positive correlation between Tpe interval and time to peak longitudinal strain in ischemic cardiomyopathy patients.

The relationship between electrocardiographic data and mortality in children diagnosed with dilated cardiomyopathy

The mortality causes of patients followed up due to dilated cardiomyopathy (DCM) include complications related to heart failure, ventricular arrhythmia, and transplantation. This study aims to evaluate the electrocardiographic findings of patients diagnosed with dilated cardiomyopathy and determine its relationship with mortality. The electrocardiographic, clinical, and laboratory findings of patients diagnosed with dilated cardiomyopathy between January 1, 2012, and September 1, 2018, in our university's pediatric cardiology department were retrospectively evaluated. The electrocardiographic findings of surviving and exitus dilated cardiomyopathy patients were compared and their effect on mortality was investigated. Twelve of the total 85 patients diagnosed with dilated cardiomyopathy were deceased. According to the electrocardiographic findings of surviving and exitus patients, there was a statistically significant difference in terms of P maximum (Pmax), P dispersion (Pdis), QT dispersion (QTdis), QTc maximum (QTcmax), QTc dispersion (QTcdis), Tp-e maximum (Tp-emax), Tp-e dispersion (Tp-edis), and QRS time. Hypertrophy and ischemia findings of electrocardiography were also statistically significant. There was a statistically significant difference between the two groups according to the echocardiographic findings of left ventricular ejection fraction (LVEF), left ventricular shortening fraction (LVSF), left ventricular end-diastolic diameter (LVEDd), and left ventricular end-systolic diameter (LVESd) measurements. It is well known that children diagnosed with dilated cardiomyopathy are at greater risk of arrhythmia compared with normal children. Although previous studies have determined the relationship between mortality and a limited number of electrocardiographic findings, especially in adults, the relationship between electrocardiography findings of children diagnosed with DCM and mortality has not been investigated before in such detail, as in our study.Conclusion: In this study, the significant difference between the electrocardiographic data of deceased and surviving dilated cardiomyopathy patients suggests that electrocardiographic data should be evaluated in detail in order to determine the low and high risk of mortality in patients with dilated cardiomyopathy.What is Known:• Previous studies on the relationship between limited electrocardiography data of adult patients diagnosed with DCM and mortality have been determinedWhat is New:• ECG data has not been investigated in such detail in child DCM patients, as in our study.

The relationship between T-wave peak-to-end interval and hemodynamic parameters in patients with pulmonary arterial hypertension

Background

T‐wave peak‐to‐end interval (TPEI) is a measure of repolarization dispersion on surface electrocardiogram (ECG). TPEI has been reported as a prognostic parameter with heart disorders. In this study, we aimed to evaluate the relationship between echocardiogram‐derived right heart parameters, right heart catheterization (RHC) measurements, and TPEI in patients with precapillary pulmonary arterial hypertension (PAH).

Methods

Thirty‐eight patients (29 females and 9 males, mean age of 54.9 ± 10.9 years) who had undergone RHC for a preliminary diagnosis of pulmonary hypertension (PH) were included in the study. We performed transthoracic echocardiography (TTE), and resting 12‐lead ECG was recorded before RHC. TPEI was measured from leads of V1‐V6, DII, DIII, and aVF, and these values are averaged to obtain the global TPEI.

Results

Duration of TPEI was significantly correlated with mean PAP, pulmonary vascular resistance (PVR), and cardiac index (CI). Longer TPEI was associated with higher N terminal probrain natriuretic peptide (NT pro‐BNP) level, lower 6‐min walk distance (6MWD), and lower tricuspid annular plane systolic excursion (TAPSE).

Conclusion

Prolongation of TPEI could be a new predictor of adverse outcome in PAH and may provide additional prognostic information for patients with PAH.

Evaluation of Tpeak–Tend and QT intervals in Chagas’ Disease, Chronic Phase and Normal Electrocardiogram

Introduction: Chagas’ disease lacks elements to predict which carriers will evolve into cardiac form and which will remain in undetermined form. Objective: To evaluate the relationship between electrocardiographic evolution and Tpeak–Tend and QT intervals, both corrected for heart rate, in chagasic patients with normal initial electrocardiogram. Method: Chagasic patients admitted to the institution until 2002 were retrospectively evaluated, and the electrocardiogram was normal at the first consultation. The Tpeak–Tend and QT intervals were measured in milliseconds at the V2 and V5 derivations, with the mean values corrected for heart rate (Bazett). The relationship of these values with the electrocardiographic evolution of the individuals was analyzed, considering the gender, time of evolution and whether they received benznidazole or not. Results: The corrected Tpeak–Tend interval showed no statistical significance among those who maintained or not normal electrocardiogram. The corrected QT interval, the treatment with benznidazole and the time of evolution showed significance for the maintenance of normal electrocardiogram. In the multivariate evaluation, treatment with benznidazole, the QTc interval and the time of evolution were independent variables for the maintenance of normal electrocardiogram. Conclusion: The Tpeak–Tend interval showed no predictor of electrocardiographic evolution. The increased QT interval favored changes.

Avaliação do Intervalo Tpico–Tfim e QT em Doença de Chagas, Fase Crônica e Eletrocardiograma Normal

Introdução: A doença de Chagas carece de elementos que proporcionem prever quais portadores evoluirão para a forma cardíaca e quais permanecerão na forma indeterminada. Objetivo:Avaliar relação entre evolução eletrocardiográfica e intervalos Tpico–Tfim e QT, ambos corrigidos para a frequência cardíaca, em chagásicos com eletrocardiograma inicial normal. Método: Avaliamos retrospectivamente chagásicos admitidos na instituição até 2002, tendo eletrocardiograma normal na primeira consulta. Os intervalos Tpico–Tfim e QT foram medidos em milissegundos nas derivações V2 e V5, sendo a média dos valores corrigida para a frequência cardíaca (Bazett). Analisou-se a relação desses valores com a evolução eletrocardiográfica dos indivíduos, tendo em vista sexo, tempo de evolução e se receberam benzonidazol ou não. Resultados: O intervalo Tpico–Tfim corrigido não mostrou significância estatística entre os que mantiveram ou não eletrocardiograma normal. O intervalo QT corrigido, o tratamento com benzonidazol e o tempo de evolução mostraram significância quanto à manutenção do eletrocardiograma normal. Na avaliação multivariada, o tratamento com benzonidazol, o intervalo QTc e o tempo de evolução se mostraram variáveis independentes para a manutenção do eletrocardiograma normal. Conclusão:O intervalo Tpico–Tfim não se mostrou preditor da evolução eletrocardiográfica. O intervalo QT aumentado favoreceu aparecimento de alterações.

Evaluation of electrocardiographic parameters in patients with epileptic seizure

The aim of the study is to evaluate the changes in electrocardiographic parameters, including QTc dispersion (QTcd), Tpeak-Tend (Tp-e)/QTc ratio and P-wave dispersion (Pd), during the period without seizure activation in patients, presented to the emergency department (ED) with epileptic seizures. This prospective case-control study was conducted between January 2017 and January 2018. Patients, over 18 years old and presented to the ED with epileptic seizure, were consecutively included in the study. Interictal period ECGs of patients were obtained at least 2 hours after the end of the postictal period. ST-segment changes, QT interval, corrected QT interval (QTc), QTd, Pd, Tp-e, Tp-e dispersion (Tp-ed), Tp-e/QTc ratio and arrhythmias were evaluated in interictal ECGs. A total of 103 epileptic patients and 31 control cases were included in the study. Heart rate, QTc, QTcd, Pd, Tp-ed and Tp-e/QTc ratio were significantly higher in the epilepsy group than in the control group (p < 0.05 for all values). No statistically significant difference in those parameters was observed between the patients with known epilepsy and the patients who had seizure for the first time. There was also no statistically significant difference between patients who had recurrent seizures during the observation period and who did not. The patients with epileptic seizures had increased Pd, QTd, QTcd, Tp-ed and Tpe/QTc ratio during interictal period compared to healthy subjects. These electrocardiographic changes might be associated with an increased risk of dysrhythmia. However, prospective large cohorts with short- and long-term follow-up are needed for clinical reflections.

Tpeak-Tend, Tpeak-Tend dispersion and Tpeak-Tend/QT in children and its relationship with clinical variables

Aim

To characterize the Tpeak-Tend, the Tpeak-Tend dispersion and Tpeak-Tend/QT in children and its relationship with clinical variables.

Methods

Cross-sectional study in 126 children between 9 and 12 years of the Camilo Cienfuegos School in Santa Clara, Cuba. Clinical and anthropometric variables were obtained to determine their relationship with electrocardiographic parameters: Tpeak-Tend V5, Tpeak-Tend dispersion and Tpeak-Tend/QT ratio V5. In addition, laboratory tests were conducted.

Results

Age and systolic blood pressure are associated with an increased probability of having values of Tpeak-Tend/QT V5 ≥75 percentile for both sexes (OR: 1.72, CI 95%: 1.02-2.91; p= 0.043), (OR: 1.08, CI 95%: 1.01-1.16; p= 0.017) respectively. The body mass index and systolic blood pressure are linearly and significantly correlated with the Tpeak-Tend/QT V5 (r= 0.224; p= 0.012) and (r= 0.220; p= 0.014) respectively.

Conclusions

The age of the patients and the systolic blood pressure figures are factors that increase the probability of having values of the Tpeak-Tend/QT V5 ≥75 percentile. There was a significant linear correlation between the Tpeak-Tend/QT V5 with the body mass index and the systolic blood pressure.

Predictive value of Tpeak-Tend interval for ventricular arrhythmia and mortality in heart failure patients with an implantable cardioverter-defibrillator: A cohort study

BACKGROUND

Tpeak-Tend interval (TpTe), a measurement of transmural dispersion of repolarization (TDR), has been shown to predict ventricular tachyarrhythmia in cardiac resynchronization therapy with defibrillator (CRT-D) patients. However, the ability of TpTe to predict ventricular tachyarrhythmia and mortality for heart failure patients with a cardioverter-defibrillator (ICD) is not clear. The purpose of this study was to assess the predictive ability of TpTe in heart failure patients with ICD.

METHODS AND RESULTS

We enrolled 318 heart failure patients treated after ICD. Patients were divided into 3 groups according to their post-implantation TpTe values and were evaluated every 6 months. The primary endpoint was appropriate ICD therapy. The secondary endpoint was all-cause mortality. During long-term follow-up, the TpTe > 110 ms group (n = 111) experienced more VT/VF episodes (45%) and all-cause mortality (25.2%) than the TpTe 90-110 ms group (n = 109) (26.4%, 14.5%) and TpTe < 90 ms group (n = 98) (11.3%, 11.3%) (overall P < .05, respectively). In Cox regression, longer post-implantation TpTe was associated with an increased number of VT/VF episodes [HR: 1.017; 95% CI: 1.008-1.026; P < .001], all-cause mortality [HR: 1.015; 95% CI: 1.004-1.027; P = .010] and the combined endpoint [HR: 1.018; 95%CI: 1.010-1.026; P < .001].

CONCLUSIONS

Post-implantation TpTe was an independent predictor of both ventricular arrhythmias and all-cause mortality in heart failure patients with an implanted ICD.

Associations between QT interval subcomponents, HIV serostatus, and inflammation

Background

The total QT interval comprises both ventricular depolarization and repolarization currents. Understanding how HIV serostatus and other risk factors influence specific QT interval subcomponents could improve our mechanistic understanding of arrhythmias.

Methods

Twelve‐lead electrocardiograms (ECGs) were acquired in 774 HIV‐infected (HIV+) and 652 HIV‐uninfected (HIV−) men from the Multicenter AIDS Cohort Study. Individual QT subcomponent intervals were analyzed: R‐onset to R‐peak, R‐peak to R‐end, JT segment, T‐onset to T‐peak, and T‐peak to T‐end. Using multivariable linear regressions, we investigated associations between HIV serostatus and covariates, including serum concentrations of inflammatory biomarkers such as interleukin‐6 (IL‐6), and each QT subcomponent.

Results

After adjustment for demographics and risk factors, HIV+ versus HIV− men differed only in repolarization phase durations with longer T‐onset to T‐peak by 2.3 ms (95% CI 0–4.5, p < .05) and T‐peak to T‐end by 1.6 ms (95% CI 0.3–2.9, p < .05). Adjusting for inflammation attenuated the strength and significance of the relationship between HIV serostatus and repolarization. The highest tertile of IL‐6 was associated with a 7.3 ms (95% CI 3.2–11.5, p < .01) longer T‐onset to T‐peak. Age, race, body mass index, alcohol use, and left ventricular hypertrophy were each associated with up to 2.2–12.5 ms longer T‐wave subcomponents.

Conclusions

HIV seropositivity, in combination with additional risk factors including increased systemic inflammation, is associated with longer T‐wave subcomponents. These findings could suggest mechanisms by which the ventricular repolarization phase is lengthened and thereby contribute to increased arrhythmic risk in men living with HIV.

Changes on the electrocardiogram in anorexia nervosa: A case control study

PURPOSE

Anorexia nervosa is a complex psychiatric condition with increased mortality. The electrocardiogram (ECG) may show repolarization changes which may associate with an increased risk of sudden death. Up to 80% of patients may be prescribed psychopharmacotherapies which alter the ECG, potentially compounding arrhythmic risk. This study aimed to describe and improve understanding of ECG changes in eating disorders and assess the effect of psychopharmacotherapies.

METHODS

Adolescent patients diagnosed with anorexia nervosa were reviewed. ECGs were reviewed by blinded expert reviewers, and repolarization parameters were compared to healthy controls. Patients on and off psychopharmacotherapies were compared.

RESULTS

Thirty-eight anorexia nervosa patients off psychopharmacotherapies were age matched to 53 healthy controls. Heart rate was lower in anorexia nervosa patients (56 vs. 74 bpm, p < 0.001). The absolute QT interval was longer in patients compared to controls (408 vs. 383 ms, p < 0.001), but the QTc by Hodges' formula was similar between groups (401 vs. 408 ms, p = 0.16). The prevalence of T-wave flattening and inversion was also similar between groups (13% vs. 4%, p = 0.12) and T-peak to T-end interval (Tpe) was shorter in patients compared to controls (p < 0.01). ECG parameters were similar between patients on and off psychopharmacotherapies aside from off-drug patients showing lower HR (56 vs. 65, p = 0.04).

CONCLUSIONS

Autonomic and repolarization changes are evident on the ECG of anorexia nervosa patients, though the QTc interval was in fact similar between groups. Changes in T-wave morphology and duration may be promising metrics of repolarization effects of anorexia nervosa.

Assessment of Tp-Te Interval and Tp-Te/Qt Ratio in Patients with Aortic Aneurysm

BACKGROUND

Arrhythmic disorders in the aortic aneurysm (AA) have been rarely reported.

AIM

The study aimed to assess the repolarisation indices of ventricular arrhythmia (VA) (mainly Tp-Te interval and Tp-Te/QT ratio) in patients with AA.

METHODS

A group of 98 patients with AA and 75 patients as control were recruited. Many of indices of ventricular arrhythmia were assessed.

RESULTS

Many of indices like QT, QTc, QTpc, Tp-Te/QT, Tp-Te/QTc, Tp-Tec/QTc, S-Tp, S-Tpc, S-Te, S-Tec and fQRS were found to be significantly different in AA group (for all P < 0.05). However, QTp, mean Tp-Te and Tp-Tec were not found different (for all P < 0.05). Aortic diameter (Ao-D) was found to have a positive correlation with QTc, QTpc, S-Tp, S-Tpc, S-Te, S-Tec, fQRS (for all P < 0,05) and negative correlation withTp-Te/QT (P = 0.047). The best cut-off level for prediction of Tp-Te ≥100 ms was found the Ao-D > 43.5 mm in ROC analysis (AUC: 0.69; P = 0.151) with sensitivity 60% and specificity 79.6%.

CONCLUSIONS

Although our study did not find any differences for mean Tp-Te interval between groups, many of other indexes of TDR were found to be significantly different. Ao-D was found to have significant correlations with many indices.

Comparing of Tp-Te Interval and Tp-Te/Qt Ratio in Patients with Preserved, Mid-Range and Reduced Ejection Fraction Heart Failure

BACKGROUND

Heart failure (HF) is classified in three class: HF with preserved EF (HFpEF); normal or LVEF ≥ 50%, HF with reduced EF (HFrEF); LEVF < 40% and newly HF mid-range EF (HFmrEF); LVEF 40-49%. On Electrocardiography (ECG) T wave, Tpeak-Tend (Tp-Te) interval reflects transmural dispersion of repolarisation (TDR) which of these indexes have been proposed as predictors of risk for ventricular arrhythmia (VA) in many cardiac diseases.

AIM

Aim of this study to asses these indices of TDR among three HF class.

METHODS

Total of 192 patients were included in this study.

RESULTS

Many of indices like Tp-Te, Tp-Te/QT wasn't different between groups (P > 0.05). But mean Q-Tpeak (QTp), S-Tend (S-Te) and S-Tpeak (S-Tp) were found significantly different between groups (P < 0.05). Again S-Te was found different according to having fragmented QRS (fQRS) on ECG (P = 0.031). Comparing to mitral inflow E/A parameters showed significant differences for Tp-Te, Tp-Tec, Tp-Te/QT, Tp-Te/QTc and Tp-Tec/QTc parameters. Finally, we found correlations between S-Te and white blood cell (WBC) (r = - 0.171; P = 0.037) and S-Tp and WBC (r = - 0.170; P = 0.038) and between S-Te and fQRS (r = 0.158; P = 0.031).

CONCLUSIONS

We didn't find differences for many of indices of TDR like Tp-Te interval between groups except QTp, S-Te, S-Tp intervals. Also, S-Te and fQRS showed significant correlation. For prediction of ventricular arrhythmia and cardiovascular death newer indexes on ECG are needed to be established in the future which will make us facilitate to distinguish high risk patients.

Optimal method of measuring the T-peak to T-end interval for risk stratification in primary prevention

Aims

Several published investigations demonstrated that a longer T-peak to T-end interval (Tpe) implies increased risk for ventricular tachyarrhythmia (VT/VF) and mortality. Tpe has been measured using diverse methods. We aimed to determine the optimal Tpe measurement method for screening purposes.

Methods and results

We evaluated 305 patients with LVEF ≤ 35% and an implantable cardioverter-defibrillator implanted for primary prevention. Tpe was measured using seven different methods described in the literature, including six manual methods and the automated algorithm '12SL', and was corrected for heart rate. Endpoints were VT/VF and death. To account for differences in the magnitude of Tpe measurements, results are expressed in standard deviation (SD) increments. We evaluated the clinical utility of each measurement method based on predictive ability, fraction of immeasurable tracings, and intra- and interobserver correlation. >Over 31 ± 23 months, 82 (27%) patients had VT/VF, and over 49 ± 21 months, 91 (30%) died. Several rate-corrected Tpe measurement methods predicted VT/VF (HR per SD 1.20-1.34; all P < 0.05), and nearly all methods (both corrected and uncorrected) predicted death (HR per SD 1.19-1.35; all P < 0.05). Optimal predictive ability, readability, and correlation were found in the automated 12SL method and the manual tangent method in lead V2.

Conclusion

For the prediction of VT/VF, the utility of Tpe depends upon the measurement method, but for the prediction of mortality, most published Tpe measurement methods are similarly predictive. Heart rate correction improves predictive ability. The automated 12SL method performs as well as any manual measurement, and among manual methods, lead V2 is most useful.

Can abnormal dispersion of ventricular repolarization be a predictor of mortality in arrhythmogenic right ventricular cardiomyopathy: The importance of Tp-e interval

BACKGROUND

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an inherited cardiomyopathy characterized by ventricular arrhythmias and specific ventricular pathology. Repolarization abnormalities, the significant contributor to life-threatening arrhythmias and mortality, are frequently observed ECG changes in patients with ARVC. This study aimed to evaluate the changes in Tp-e interval, Tp-e/QT, Tp-e/QTc ratio, and traditional electrocardiographic features of electrical dispersion in patients with ARVC.

METHODS

A total of 105 participants were enrolled in the current study. The ARVC group consisted of 40 subjects (30 men, with a median of 35 (26-41) years), and the control group included of 65 age and sex-matched individuals (42 men, with a median of 37 (24-45) years). The Tp-e interval, Tp-e/QT ratio, and Tp-e/QTc ratio were measured by the 12-lead electrocardiogram.

RESULTS

Tp-e interval, cTp-e interval, Tp-e/QT, and Tp-e/QTc ratio were significantly higher in ARVC patients compared to the control group (all p < 0.001). Tp-e interval, cTp-e interval, Tp-e/QT ratio, and Tp-e/QTc ratio were significantly increased in deceased ARVC patients compared to the survival group (p = 0.038, p < 0.001, p = 0.006, p = 0.032, respectively). In the multivariate analysis, RV-FAC and cTp-e interval level (p < 0.05 for each parameter) were associated with all-cause mortality [odds ratio 1.747 95% CI (1.012-3.018); p = 0.045 and odds ratio 1.166, 95% CI (1.017-1.336); p = 0.027, respectively].

CONCLUSION

Tp-e interval, cTp-e interval, Tp-e/QT ratio, and Tp-e/QTc ratio were prolonged in patients with NC. We revealed that abnormal dispersion of ventricular repolarization suggests the increased risk of mortality in ARVC.

QTc ınterval is prolonged in Wilson's disease with neurologic ınvolvement

Background Neurologic and liver involvement in Wilson's disease (WD) is well-documented, however, few reports demonstrated cardiac involvement. Tpe and Tpe/QT are new measures of ventricular repolarization which were recently suggested as predictor of arrythmogenesis. We aimed to evaluate ventricular depolarization and repolarization parameters including QT, QTc, Tpe intervals, Tpe/QT, Tpe/QTc ratios, and QT dispersion (QTd) in patients with WD. Materials and methods Thirty-five patients with WD and 30 healthy controls were included in the study. Patients were evaluated by a neurologist in addition to MR imaging. Twenty-one of 35 patients were diagnosed as neuroWilson (NW), whereas 14 patients as non-NW. ECG recordings were obtained using a 12-lead commercial device (Cardiac Science, Burdick s500,USA). All patients underwent standard echocardiographic evaluation. These two groups of patients and healthy controls were compared. Results There were no difference between patients with WD and healthy controls in terms of age sex, BMI, liver, and kidney functions where as patients with WD were anemic and thrombocytopenic. Left atrial, ventricular dimensions, left ventricular systolic, and diastolic functions were similar between patients and healthy control. QT interval was prolonged in patient group, however, QTc, Tpe intervals, Tpe/QT, and Tpe/QTc ratios and QTd did not differ between groups. When patients with NW and non-NW were compared, both QT and QTc intervals were significantly longer in patients with NW, however, Tpe interval, Tpe/QT and Tpe/QTc ratios, and QTd did not differ. Conclusion QT and QTc intervals are prolonged in patients with Wilson's disease and neurologic involvement.

The assessment of P-wave dispersion and myocardial repolarization parameters in patients with chronic kidney disease

Objective: The risks of sudden death and cardiac arrhythmia are increased in patients with chronic kidney disease (CKD). Here, we aimed to evaluate the indicators of arrhythmias, such as p-wave dispersion (P-WD), QTc dispersion, Tp-e and Tp-e/QT ratio in patients with CKD stages 3–5 on no renal replacement therapy (RRT).

Material and methods: One-hundred and thirty three patients with CKD stages 3–5 and 32 healthy controls were enrolled into the study. No patients received RRT. QTc dispersion, P-WD and Tp-e interval were measured using electrocardiogram and Tp-e/QT ratio was also calculated.

Results: Mean age rates were found similar in patients and controls (60.8 ± 14.2 and 61 ± 12.9 y, p = .937, respectively). Compared patients with controls, P-WD (45.85 ± 12.42 vs. 21.17 ± 6.6 msec, p < .001), QTc-min (366.99 ± 42.31 vs. 387.15 ± 20.5 msec, p < .001), QTc dispersion (71.13 ± 27.95 vs. 41.25 ± 14.55 msec, p < .001), Tp-e maximum (81.04 ± 10.34 vs. 75.49 ± 10.9 msec, p < .001), Tp-e minimum (62.25 ± 7.58 vs. 54.8 ± 6.72 msec, p < .001) and Tp-e/QTc ratio (0.19 ± 0.02 vs. 0.18 ± 0.01, p = .001) were found to be different. QTc-max and Tp-e interval were found to be similar in both groups.

Conclusion: P-WD and QTc dispersion, Tp-e interval and Tp-e/QTc ratio were found to be increased in with CKD stages 3–5 on no RRT.

Reduced N-Type Ca2+ Channels in Atrioventricular Ganglion Neurons Are Involved in Ventricular Arrhythmogenesis

Background

Attenuated cardiac vagal activity is associated with ventricular arrhythmogenesis and related mortality in patients with chronic heart failure. Our recent study has shown that expression of N‐type Ca²⁺ channel α‐subunits (Ca_v2.2‐α) and N‐type Ca²⁺ currents are reduced in intracardiac ganglion neurons from rats with chronic heart failure. Rat intracardiac ganglia are divided into the atrioventricular ganglion (AVG) and sinoatrial ganglion. Ventricular myocardium receives projection of neuronal terminals only from the AVG. In this study we tested whether a decrease in N‐type Ca²⁺ channels in AVG neurons contributes to ventricular arrhythmogenesis.

Methods and Results

Lentiviral Ca_v2.2‐α shRNA (2 μL, 2×10⁷ pfu/mL) or scrambled shRNA was in vivo transfected into rat AVG neurons. Nontransfected sham rats served as controls. Using real‐time single‐cell polymerase chain reaction and reverse‐phase protein array, we found that in vivo transfection of Ca_v2.2‐α shRNA decreased expression of Ca_v2.2‐α mRNA and protein in rat AVG neurons. Whole‐cell patch‐clamp data showed that Ca_v2.2‐α shRNA reduced N‐type Ca²⁺ currents and cell excitability in AVG neurons. The data from telemetry electrocardiographic recording demonstrated that 83% (5 out of 6) of conscious rats with Ca_v2.2‐α shRNA transfection had premature ventricular contractions (P<0.05 versus 0% of nontransfected sham rats or scrambled shRNA‐transfected rats). Additionally, an index of susceptibility to ventricular arrhythmias, inducibility of ventricular arrhythmias evoked by programmed electrical stimulation, was higher in rats with Ca_v2.2‐α shRNA transfection compared with nontransfected sham rats and scrambled shRNA‐transfected rats.

Conclusions

A decrease in N‐type Ca²⁺ channels in AVG neurons attenuates vagal control of ventricular myocardium, thereby initiating ventricular arrhythmias.

Is myocardial repolarization duration associated with repolarization heterogeneity?

BACKGROUND

Dispersion of repolarization is theorized as one mechanism by which myocardial repolarization prolongation causes lethal torsades de pointes, (TdP). Our primary purpose was to determine whether prolongation of myocardial repolarization as measured by the heart rate-corrected J-to-T peak interval (JTpkc), is associated with repolarization heterogeneity as measured by transmural dispersion, defined as the median duration from the peak to the end of the T wave (TpTe).

METHODS

A retrospective cohort study was performed at a single urban tertiary ED from July 2011-September 2012. Inclusion criteria included all consecutive ED patients with ECG based on QTc and QRS intervals. Automated measurements of all intervals were performed. The association of JTpkc with the dependent variable TpTe was assessed after adjustment for QRS and RR interval durations with a multiple linear regression model. A secondary analysis included a similar adjusted assessment of the association of JTpkc with QT dispersion, QTd. Finally, we constructed two multiple regression models to assess the association of clinical causative factors of TdP with TpTe and JTpkc.

RESULTS

Eight hundred seventy-four cases were included: 186 with QTc <500 ms, 118 with QTc ≥500 and QRS ≥120 ms, and 570 with QTc ≥500 and QRS <120 ms. The coefficient for association of JTpkc with TpTe was -0.10 (95%CI -0.15 to -0.05), and for JTpkc with QTd was 0.03 (95% CI -0.01 to 0.06). Clinical causative TdP factors were associated more with JTpkc than TpTe.

CONCLUSION

Repolarization duration as measured by JTpkc is not positively associated with dispersion of repolarization as measured by TpTe or QTd. Dispersion of repolarization may not be a critical mechanistic link between QTc prolongation and TdP.

Electrocardiographic Markers of Appropriate Implantable Cardioverter-Defibrillator Therapy in Young People with Congenital Heart Diseases

Implantable cardioverter-defibrillators (ICDs) are increasingly utilized in patients with congenital heart disease (CHD). Prediction of the occurrence of shocks is important if improved patient selection is desired. The electrocardiogram (ECG) has been the first-line tool predicting the risk of sudden death, but data in CHD patients are lacking. We aim to evaluate the predictive value of electrocardiographic markers of appropriate therapy of ICD in young people with CHD. We conducted a prospective, longitudinal study, in twenty-six CHD patients (mean age 24.7 ± 5.3 years) who underwent first ICD implantation. Forty-two age- and diagnosis-matched controls were recruited. Twelve-lead ECG and 24 h Holter analysis were performed during a mean follow-up of 38.9 months. Data included heart rate, heart rate variability, QRS duration (QRSd), QTc interval and its dispersion, Tpeak-Tend (Tp-Te) interval and its dispersion, presence of fragmented QRS (fQRS), T wave alternans, atrial arrhythmias, and non-sustained ventricular tachycardia. Implant indication was primary prevention in ten cases (38.5%) and secondary prevention in 16 (61.5%). Overall, 17 subjects (65.3%) received at least one appropriate and effective ICD discharge. fQRS was present in 64.7% of cases with ICD therapy compared with patients without events or controls (p < 0.0001). Tp-e and Tp-e dispersion were significantly prolonged in patients with recurrences (113.5 and 37.2 ms) versus patients without ICD discharge (89.6 and 24.1 ms) or controls (72.4 and 19.3 ms) (p < 0.0001 and p < 0.0001, respectively). On univariate Cox regression analysis QRSd (hazard ratio: 1.19 per ms, p = 0.003), QTc dispersion (hazard ratio: 1.57 per ms, p = 0.002), fQRS (hazard ratio: 3.58 p < 0.0001), Tp-e (hazard ratio: 2.27 per ms, p < 0.0001), and Tp-e dispersion (hazard ratio: 4.15 per ms, p < 0.0001), emerged as strong predictors of outcome. On multivariate Cox analysis fQRS, Tp-e and Tp-e dispersion remained in the model. The presence of fQRS, and both Tp-e and Tp-e dispersion are useful ECG tools in daily clinical practice to identify CHD patients at risk for appropriate ICD therapy.

The evaluation of a new marker of transmyocardial repolarization parameters in ischemic stroke patients; T peak-T end (T p-e), T p-e/QTc

The cardiovascular manifestations of acute ischemic stroke have been well known. Several electrocardiography (ECG) abnormalities have been reported in patients following acute stroke, including QT interval prolongation, ST segment deviation and T-wave changes. This study aimed to investigate the changes in transmyocardial repolarization parameters, in ischemic stroke patients. The study is a prospective, blind, and controlled clinical study. The patients without cardiac disease who received ischemic stroke diagnoses were included in the study. ECG was received from the patients in the first hour and 72 h. The P, QT, T _p-e, T _p-e dispersion, and the T _p-e/QT ratio were calculated. Moreover, fifty-five stroke patients and 35 control subjects were included to the study. All dispersion values and T _p-e/QT_c ratio in patients group were higher than those of control group (p < 0.05 for all values). When evaluated between ECGs' on first and third days, it was found that decreasing on all dispersion values and T _p-e/QT_c ratio in ECGs on third day than ECGs on first day (p < 0.05 for all values). QT, QT_c, and T _p-e dispersions values in patients who have insular lobe involvement were higher than those of patients who do not have insular lobe involvement (p < 0.001 for all values). In this study, we showed that acute stroke increases that P _d, QT_d, QT_cd and new repolarization markers T _p-e and T _p-e/QT_c, during first 24 and 72 h in acute stroke patients without cardiovascular disease compared with the control group. The physicians should be aware about ventricular dysrhythmias in patients with ischemic stroke and these patients closely observed with cardiac monitoring, especially within first 24 h, and especially patients with insular lobe involvement.

Variability of Myocardial Repolarization in Pediatric Patients with a Ventricular Septal Defect

In patients with a ventricular septal defect, left-to-right shunting increases the left ventricular preload. This pathological change affects myocardial depolarization and repolarization and has the potential to evoke arrhythmogenic substrates. We examined the effect of ventricular septal defects on myocardial repolarization by investigating the variability in the repolarization interval. This retrospective study included 19 patients (mean age, 1.8 ± 2.1 years) who underwent surgical closure (mean left-to-right shunt ratio, 2.60 ± 0.55) and 26 age-matched healthy controls from 2008 to 2015. Using preoperative electrocardiograms, we studied two electrocardiographic parameters (heart rate-corrected repolarization and variability of repolarization) and four repolarization intervals (QT, JT, J point to T peak [JTp], and T peak to T end [Tp-e] intervals). The variability index (VI) was calculated from the logarithm of the ratio of the repolarization parameter variance to heart rate variance. The various measures were compared between the patients and controls, and significant differences were found in the corrected QT, JTp, and Tp-e intervals (p < 0.05). The VI of the four intervals also showed significant differences (patients vs.

CONTROLS

QTVI, -0.55 ± 0.61 vs. -1.10 ± 0.53; JTVI, -0.33 ± 0.60 vs. -0.86 ± 0.57; JTpVI, -0.15 ± 0.78 vs. -0.73 ± 0.56; Tp-eVI, 0.75 ± 0.70 vs. 0.11 ± 0.73, respectively; p < 0.05). No correlation was found between the QTVI and corrected QT interval using linear regression analysis. These repolarization characteristics provide not only electrophysiological indices but also a new index with which to assess the pathophysiology of congenital heart disease.

Tpeak-to-Tend interval corrected for heart rate: A more precise measure of increased sudden death risk?

BACKGROUND

The Tpeak to Tend (Tpe) interval on the 12-lead electrocardiogram predicts an increased risk of sudden cardiac arrest (SCA). There is controversy over whether Tpe would be more useful if corrected for heart rate (Tpec).

OBJECTIVES

We evaluated whether the predictive value of Tpe for SCA improves with heart rate correction and sought to determine an optimal cutoff value for Tpec in the context of SCA risk.

METHODS

Cases of SCA (n = 628; mean age 66.4 ± 14.5 years; n = 416, 66.2% men) from the Oregon Sudden Unexpected Death Study with an archived electrocardiogram available prior and unrelated to the SCA event were analyzed. Comparisons were made with control subjects (n = 819; mean age 66.7 ± 11.5 years; n = 559, 68.2% men). The Tpe interval was corrected for heart rate using Bazett (TpecBa) and Fridericia (TpecFd) formulas, and the predictive value of Tpec for SCA was evaluated using logistic regression models.

RESULTS

The area under the curve for Tpec predicting SCA improved with both correction formulas. TpecBa and TpecFd were shown to have an area under the curve of 0.695 and 0.672, respectively, as compared with a baseline of 0.601 with an uncorrected Tpe. A TpecBa value of >90 ms was predictive of SCA, independent of age, sex, comorbidities, QRS duration, corrected QT interval, and severely reduced left ventricular ejection fraction (≤35%; odds ratio 2.8; 95% confidence interval 1.92-4.17; P < .0001).

CONCLUSION

Correcting Tpe for heart rate, using either the Bazett or the Fridericia formula, improved the independent predictive value of this marker for the assessment of SCA risk. Prolongation of TpecBa beyond 90 ms was associated with a nearly 3-fold increased risk of SCA.

Analysis of ECG Measures of Cardiac Repolarization in Relation to Arrhythmic Events in an Implantable Cardioverter Defibrillator Population

BACKGROUND

ECG-derived measures of cardiac repolarization may have utility in risk prediction of future ventricular arrhythmia, and a range of different measures have been proposed. We compared time-based, vectorcardiographic, and singular value decomposition (SVD) derived measures of repolarization to determine which was most predictive of appropriate therapy in an ICD population.

METHODS

We examined the independent prognostic value of a range of repolarization measures derived from 60 second 12-lead ECG recordings in 150 patients receiving new ICD implants in relation to the occurrence of appropriate therapy during follow-up.

RESULTS

Over an average follow-up of 2.15 ± 0.87 years, male gender, presence of premature ventricular complex (PVC), relative T wave residuum (TWR-rel, measures regional repolarization heterogeneity), and TCRT (the total cosine R-to-T, describes the global angle between repolarization and depolarization wavefronts) were the only independent predictors of appropriate therapy. With every 0.01% increase in TWR-rel, there was 2% increased risk of appropriate therapy (HR = 1.02, 95% CI 1.006-1.034, P < 0.001). With every 1° decrease in TCRT, there was an increase in arrhythmic risk of 0.9% (HR 1.009, 95% CI 1.003-1.015, P = 0.003).

CONCLUSIONS

The use of advanced analytic ECG techniques to derive measures of repolarization abnormality might shave utility in risk stratification in an ICD population.

Surface Electrocardiogram Predictors of Sudden Cardiac Arrest

BACKGROUND

Heart disease is a major cause of death in industrialized nations, with approximately 50% of these deaths attributable to sudden cardiac arrest. If patients at high risk for sudden cardiac arrest can be identified, their odds of surviving fatal arrhythmias can be significantly improved through prophylactic implantable cardioverter defibrillator placement. This review summarizes the current knowledge pertaining to surface electrocardiogram (ECG) predictors of sudden cardiac arrest.

METHODS

We conducted a literature review focused on methods of predicting sudden cardiac arrest through noninvasive electrocardiographic testing.

RESULTS

Several electrocardiographic-based methods of risk stratification of sudden cardiac arrest have been studied, including QT prolongation, QRS duration, fragmented QRS complexes, early repolarization, Holter monitoring, heart rate variability, heart rate turbulence, signal-averaged ECG, T wave alternans, and T-peak to T-end. These ECG findings have shown variable effectiveness as screening tools.

CONCLUSION

At this time, no individual ECG finding has been found to be able to adequately stratify patients with regard to risk for sudden cardiac arrest. However, one or more of these candidate surface ECG parameters may become useful components of future multifactorial risk stratification calculators.

T-wave reversal in the augmented unipolar right arm electrocardiographic lead is associated with increased risk of sudden death

BACKGROUND

Repolarization abnormalities are associated with ventricular arrhythmias, and published studies report that a reversal of T wave polarity (positive or flat T wave) in lead aVR may be linked to increased cardiovascular mortality. We evaluated whether a positive or flat T wave in aVR is a risk marker for sudden cardiac death (SCD).

METHODS

SCD cases from the Oregon Sudden Unexpected Death Study (catchment population ~1 million) were compared to geographic controls with coronary artery disease and no history of SCD. Archived electrocardiograms performed prior and unrelated to the SCD event were evaluated.

RESULTS

SCD cases (n = 691, 67.6 ± 14.9 years, 69% male) were more likely than controls (n = 663, 66.2 ± 11.6 years, 67% male) to have diabetes (40 vs 32%; p < 0.01), left ventricular ejection fraction (LVEF) ≤35% (27 vs 11 %; p < 0.01), prolonged QTc (≥450 ms; 54 vs 28%; p < 0.01) and positive (19 vs 13%; p < 0.01) or flat T wave (14 vs 7%; p < 0.01) in aVR. On multivariable analysis, a positive/flat T wave in aVR was independently associated with SCD (OR 1.9, 95% CI 1.3-2.8, p < 0.01). However, a positive T wave alone lost statistical significance in patients with LVEF ≤ 35% and QTc ≥ 450 ms. In a subgroup analysis among patients with normal LVEF, QTc, and no diabetes, a positive T wave in aVR (but not a flat T wave) remained associated with SCD (OR 2.8, 95% CI 1.2-6.1, p < 0.01).

CONCLUSIONS

A positive or flat T wave in lead aVR was associated with SCD in subsets of patients. This simple ECG marker in this often-ignored lead may contribute to enhancement of SCD risk stratification, and warrants further evaluation.

Effects of droperidol and ondansetron on dispersion of ventricular repolarization: A randomized double-blind clinical study in anesthetized adult patients

BACKGROUND AND OBJECTIVE

Droperidol and ondansetron prolong QT interval, a circumstance that has raised some concerns regarding the possibility of inducing torsades de pointes (TdP). However drug-induced spatial dispersion of ventricular repolarization has been shown to be the principal arrhythmogenic substrate for TdP. The aim of this study is to explore the effects of droperidol and ondansetron on the dispersion of repolarization, measured using the T peak-to-end interval (Tp-e) and Tp-e/QT and Tp-e/RR(1/2) ratios in surgical anesthetized patients.

METHODS

A randomized, double-blind study carried out on sixty-three adult patients without cardiac disease or factors favoring QT prolongation and undergoing non-cardiac surgery were randomly assigned to the droperidol or ondansetron group. Under propofol anesthesia, a 12-lead EKG was obtained, and 1.25mg droperidol or 4mg ondansetron was injected. Five minutes later, a new 12-lead EKG was recorded. EKG analyses were independently performed by two cardiologists blinded to the state of the traces or group allocation. QT, RR and Tp-e intervals were measured by averaging five successive beats in leadII (QT) or V5 (Tp-e). The mean value for each measurement was calculated for statistical analysis.

RESULTS

Thirty-two patients (19 women) received droperidol, and 31 (22 women) ondansetron. Droperidol and ondansetron prolonged the QTcF interval (Fridericia formula) by 6.8 and 7.2ms (mean values) respectively, but neither droperidol nor ondansetron increased the Tp-e interval or Tp-e/QT and Tp-e/RR(1/2) ratios.

CONCLUSION

At antiemetic doses, neither ondansetron (4mg) nor droperidol (1.25mg) increases the dispersion of ventricular repolarization in healthy adult patients anesthetized with propofol.

Acute effects of Red Bull energy drink on ventricular repolarization in healthy young volunteers: a prospective study

OBJECTIVE

Energy drinks (EDs) are widely consumed products of the beverage industry and are often chosen by teenagers and young adults. Several adverse cardiovascular events and malignant cardiac arrhythmias following consumption of EDs have been reported in the literature. Several studies have suggested that the interval from the peak to the end of the electrocardiographic T wave (Tp-e) may correspond to the dispersion of repolarization and that an increased Tp-e interval and Tp-e/QT ratio are associated with malignant ventricular arrhythmias. This study investigated the acute effects of Red Bull ED on ventricular repolarization as assessed by the Tp-e interval and Tp-e/QT ratio.

METHODS

A prospective, open-label study design was used. After an 8-h fast, 50 young, healthy subjects consumed 355 mL of Red Bull ED. The Tp-e interval, Tp-e/QTc ratio, and several other electrocardiographic parameters were measured at baseline and 2 h after ingestion of Red Bull ED.

RESULTS

No significant changes in the Tp-e interval or Tp-e/QTc ratio were observed with Red Bull ED consumption. Red Bull ED consumption led to increases in both systolic and diastolic blood pressures, which were associated with an increased heart rate.

CONCLUSION

Although ingestion of Red Bull ED increases the heart rate and diastolic and systolic blood pressures, it does not cause alterations in ventricular repolarization as assessed by the Tp-e interval and Tp-e/QTc ratio.

Ventricular repolarization markers for predicting malignant arrhythmias in clinical practice

Malignant cardiac arrhythmias which result in sudden cardiac death may be present in individuals apparently healthy or be associated with other medical conditions. The way to predict their appearance represents a challenge for the medical community due to the tragic outcomes in most cases. In the last two decades some ventricular repolarization (VR) markers have been found to be useful to predict malignant cardiac arrhythmias in several clinical conditions. The corrected QT, QT dispersion, Tpeak-Tend, Tpeak-Tend dispersion and Tp-e/QT have been studied and implemented in clinical practice for this purpose. These markers are obtained from 12 lead surface electrocardiogram. In this review we discuss how these markers have demonstrated to be effective to predict malignant arrhythmias in medical conditions such as long and short QT syndromes, Brugada syndrome, early repolarization syndrome, acute myocardial ischemia, heart failure, hypertension, diabetes mellitus, obesity and highly trained athletes. Also the main pathophysiological mechanisms that explain the arrhythmogenic predisposition in these diseases and the basis for the VR markers are discussed. However, the same results have not been found in all conditions. Further studies are needed to reach a global consensus in order to incorporate these VR parameters in risk stratification of these patients.

T-peak to T-end interval for prediction of ventricular tachyarrhythmia and mortality in a primary prevention population with systolic cardiomyopathy

BACKGROUND

The electrocardiographic T-wave peak to T-wave end interval (Tpe) correlates with dispersion of ventricular repolarization (DVR). Increased DVR increases propensity toward electrical reentry that can cause ventricular tachyarrhythmia. The baseline rate-corrected Tpe (Tpec) has been shown to predict ventricular tachyarrhythmia and death in multiple patient populations but not among cardiomyopathic patients undergoing insertion of an implantable cardioverter-defibrillator (ICD) for primary prevention.

OBJECTIVE

The purpose of this study was to assess the risk stratification ability of the Tpec in patients with systolic cardiomyopathy without prior ventricular tachyarrhythmia (ie, the primary prevention population).

METHODS

We performed prospective follow-up of 305 patients (73% men; left ventricular ejection fraction [LVEF] 23 ± 7%) with LVEF ≤35% and an ICD implanted for primary prevention. Baseline ECGs were analyzed with automated algorithms. Endpoints were ventricular tachycardia (VT)/ventricular fibrillation (VF), death, and a combined endpoint of VT/VF or death, assessed by device follow-up and Social Security Death Index query.

RESULTS

The average Tpec was 107 ± 22 ms. During device clinic follow-up of 31 ± 23 months, 82 patients (27%) had appropriate ICD therapy for VT/VF, and during mortality follow-up of 49 ± 21 months, 91 patients (30%) died. On univariable analysis, Tpec predicted VT/VF, death, and the combined endpoint of VT/VF or death (P < .05 for each endpoint). Multivariable analysis included univariable predictors among demographics, clinical data, laboratory data, medications used, and electrocardiography parameters. After correction, Tpec remained predictive of VT/VF (hazard ratio [HR] per 10-ms increase 1.16, P = .009), all-cause mortality (HR per 10 ms 1.13, P = .05), and the combined endpoint (HR per 10 ms 1.17, P = .001).

CONCLUSION

Tpec independently predicts both VT/VF and overall mortality in patients with systolic dysfunction and ICDs implanted for primary prevention.

QRS fragmentation and the risk of sudden cardiac death in MADIT II

BACKGROUND

QRS fragmentation (fQRS) has been reported as a useful ECG parameter in predicting mortality in high-risk postinfarction patients. Its prognostic value for sudden cardiac death (SCD) and ventricular arrhythmias in ischemic cardiomyopathy (ICM) remains unknown.

METHODS

MADIT II enrollment 12-lead ECGs were analyzed for fQRS defined as RSR' patterns (≥1 R' or notching of S or R wave) in patients with a normal QRS duration and >2 notches on the R or S wave in patients with abnormal QRS duration, present in 2 contiguous leads. Exclusion criteria included a paced rhythm and an uninterpretable or incomplete ECG. Study endpoints included SCD, SCD or appropriate implantable cardioverter defibrillator (ICD) shock, and total mortality (TM).

RESULTS

Of the 1,232 ECGs reviewed, 1,040 were of suitable quality for fQRS analysis. QRS fragmentation was found in 33% of patients in any leads, in 10% of patients in anterior leads, in 8% of patients in lateral leads and in 21% of patients in inferior leads. Anterior and lateral location of QRS fragmentation was not associated with follow-up events. Inferior location of fQRS was found to be predictive of SCD/ICD shock (hazard ratio [HR] 1.46, P = 0.032), SCD (HR 2.05, P = 0.007), and TM (HR 1.44, P = 0.036). This association was driven primarily by the increase in events found in LBBB patients: SCD/ICD shock (HR 2.05, P = 0.046), SCD (HR 4.24, P = 0.002), and TM (HR 2.82, P = 0.001).

CONCLUSIONS

Fragmented QRS, especially identified in inferior leads, is predictive of SCD, SCD or appropriate ICD shock, and all-cause mortality in patients with ICM. Identifying inferior fQRS in patients with LBBB is of particular prognostic significance and should reinforce the use of ICD therapy in this high-risk group.