OBJECTIVE: The first aim of this study was to assess the predictive power of Tend interval (Te) and non-invasive hemodynamic markers, based on bioimpedance in decompensated chronic heart failure (CHF). The second one was to verify the possible differences in repolarization and hemodynamic data between CHF patients grouped by level of left ventricular ejection fraction (LVEF). Finally, we wanted to check if repolarization and hemodynamic data changed with clinical improvement or worsening in CHF patients.
METHODS: Two hundred and forty-three decompensated CHF patients were studied by 5 min ECG recordings to determine the mean and standard deviation (TeSD) of Te (first study). In a subgroup of 129 patients (second study), non-invasive hemodynamic and repolarization data were recorded for further evaluation.
RESULTS: Total in-hospital and cardiovascular mortality rates were respectively 19 and 9%. Te was higher in the deceased than in surviving subjects (Te: 120 ± 28 vs. 100 ± 25 ms) and multivariable logistic regression analysis reported that Te was related to an increase of total (χ2: 35.45, odds ratio: 1.03, 95% confidence limit: 1.02-1.05, p < 0.001) and cardiovascular mortality (χ2: 32.58, odds ratio: 1.04, 95% confidence limit: 1.02-1.06, p < 0.001). Subjects with heart failure with reduced ejection fraction (HFrEF) reported higher levels of repolarization and lower non-invasive systolic hemodynamic data in comparison to those with preserved ejection fraction (HFpEF). In the subgroup, patients with the NT-proBNP reduction after therapy showed a lower rate of Te, heart rate, blood pressures, contractility index, and left ventricular ejection time in comparison with the patients without NT-proBNP reduction.
CONCLUSIONS: Electrical signals from ECG and bioimpedance were capable of monitoring the patients with advanced decompensated CHF. These simple, inexpensive, non-invasive, easily repeatable, and transmissible markers could represent a tool to remotely monitor and to intercept the possible worsening of these patients early by machine learning and artificial intelligence tools.

Electronic cigarettes are often used for smoking cessation as a harm reduction strategy, but studies comparing risks of electronic cigarettes (ECs) and tobacco cigarettes (TCs) are scarce. Ventricular repolarization in people who smoke TCs is abnormal. Baseline repolarization was compared among nonusers (people who do not use TCs or ECs) and people who use ECs or TCs. The acute effects of ECs and TCs on metrics of ventricular repolarization were then compared in people who chronically smoke. A total of 110 participants (59 female), including 35 people (21 females) in the TC cohort, 34 people (17 females) in the EC cohort, and 41 people (21 females) in the nonuser cohort, were included. None of the primary outcomes, Tpeak-end (Tp-e), Tp-e/QT, and Tp-e/QTc, were different among the three cohorts at supine baseline, even when adjusted for sex. When compared with the control exposure standing after acutely using the EC but not the TC, significantly prolonged all three primary indices of ventricular repolarization in people who smoke TCs. The major new finding in this study is that in people who smoke TCs, using an EC compared with a TC significantly prolongs ventricular repolarization. Furthermore, in our subgroup analysis by sex, this adverse effect on repolarization is found only in male, not female, smokers. In summary, chronic TC smoking is the most prevalent, modifiable risk factor for cardiovascular death, including sudden cardiac death. If used for smoking cessation, ECs should only be used in the short term since they too carry their own risks; this risk appears to be greatest in males compared with females who smoke.NEW & NOTEWORTHY The major new finding in this study is that in people who smoke tobacco cigarettes, using an electronic cigarette but not a tobacco cigarette acutely and significantly prolongs several metrics of ventricular repolarization, including Tpeak-Tend, Tpeak-Tend/QT, and Tpeak-Tend/QTc. Furthermore, in our subgroup analysis by sex, this adverse effect on repolarization is found only in male, not female, smokers.

The association between chronic heart failure (CHF) and permanent atrial fibrillation is very frequent. The repolarization duration was already found predictive for atrial fibrillation. Aim of this study was to evaluate the influence of atrial fibrillation on short period repolarization variables in decompensated CHF patients.
We used 5 min ECG recordings to assess the mean, standard deviation (SD), and normalized variance (NV) of the following variables: QT end (QTe), QT peak (QTp), and T peak to T end (Te) in 121 decompensated CHF, of whom 40 had permanent atrial fibrillation, too. We reported also the 30-day mortality.
QTpSD (p < .01), TeSD (p < .01), QTpVN (p < .01), and TeVN (p < .01) were higher in the atrial fibrillation than among sinus rhythm CHF subjects. Multivariable logistic analysis selected only TeSD (odd ratio, o.r.: 1.32, 95% confidence interval, c.i.: 1.06-1.65, p: .015) associated with atrial fibrillation. A total of 27 patients died during the 30-days follow-up (overall mortality rate 22%), 7 (18%), and 20 (25%) respectively in the atrial fibrillation and sinus rhythm patients. Furthermore, the following variables were associated to the morality risk: NT-pro Brain Natriuretic Peptide (o.r.: 1.00, 95% c.i.: 1.00-1.00, p: .041), left ventricular end diastolic diameter (o.r.: 0.81, 95% c.i.: 0.67-0.96, p: .010), and Te mean (o.r.: 1.04, 95% c.i.: 1.02-1.09, p: .012).
In decompensated CHF subjects, Te mean seems be associated to mortality and TeSD to the permanent atrial fibrillation. We could hypothesize that, during severe CHF, the multi-level ionic CHF channel derangement could be critical in influencing these non-invasive markers. (ClinicalTrials.gov number, NCT04127162).

Women are associated with longer electrocardiographic QT intervals and increased proarrhythmic risks of QT-prolonging drugs. The purpose of this study was to characterize the differences in cardiac electrophysiology between moxifloxacin and levofloxacin in men and women and to assess the balance of inward and outward currents through the analysis of QT subintervals. Data from 2 TQT studies were used to investigate the impact of moxifloxacin (400 mg) and levofloxacin (1000 and 1500 mg) on QT subintervals using algorithms for measurement of J-Tpeak and Tpeak -Tend intervals. Concentration-effect analyses were performed to establish potential relationships between the ECG effects and the concentrations of the 2 fluoroquinolones. Moxifloxacin was shown to be a more potent prolonger of QT interval corrected by Fredericia (QTcF) and had a pronounced effect on J-Tpeak c. Levofloxacin had little effect on J-Tpeak c. For moxifloxacin, the concentration-effect modeling showed a greater effect for women on QTcF and J-Tpeak c, whereas for levofloxacin the inverse was true: women had smaller QTcF and J-Tpeak c effects. The different patterns in repolarization after administration of both drugs suggested a sex difference, which may be related to the combined IKs and IKr inhibitory properties of moxifloxacin versus IKr suppression only of levofloxacin. The equipotent inhibition of IKs and IKr appears to affect women more than men. Sex hormones are known to influence cardiac ion channel expression and differences in QT duration. Differences in IKr and IKs balances, influenced by sex hormones, may explain the results. These results support the impact of sex differences on the cardiac safety assessment of drugs.

OBJECTIVE: Adult congenital heart disease (ACHD) patients are at risk of sudden cardiac death (SCD). However, methods for risk stratification are not yet well-defined. The Tpeak -Tend (TpTe) interval, a measure of dispersion of ventricular repolarization, is a risk factor for SCD in non-ACHD patients. We aim to evaluate whether TpTe can be used in risk stratification for SCD in ACHD patients.
METHODS: From an international multicenter cohort of 25 790 ACHD patients, we identified all SCD cases. Cases were matched to controls by age, gender, congenital defect, and (surgical) intervention.
METHODS: TpTe was measured on a standard 12-lead ECG. The maximum TpTe of all ECG leads (TpTe-max), mean (TpTe-mean), and TpTe dispersion (maximum minus minimum) were obtained. Odds ratios (OR) for SCD cases vs controls were calculated using conditional logistic regression analysis.
RESULTS: ECGs were available for 147 cases (median age at death 33.5 years (quartiles 26.2, 48.7), 66% male) and 267 controls. The mean TpTe-max was 97 ± 24 ms in cases vs 84 ± 17 ms in controls (P < .001); TpTe-mean was 70 ± 16 vs 63 ± 10 ms (P < .001); and dispersion was 51 ± 22 ms vs 41 ± 16 ms (P = .02), respectively. Assessing each ECG lead separately, TpTe in lead aVR predicted SCD most accurately. TpTe in lead aVR was 71 ± 23 ms in cases vs 61 ± 13 ms in controls (P < .001). After adjusting for impaired ventricular function, heart failure symptoms, and prolonged QRS duration, the OR of SCD of TpTe in lead aVR at an optimal cutoff of 80 ms was 5.8 (95% CI 2.7-12.4, P < .001).
CONCLUSIONS: The TpTe interval is associated with SCD in ACHD patients. Particularly, TpTe in lead aVR can be used as an independent risk factor for SCD in ACHD patients and may, therefore, add precision to current risk prediction models.

The fraction of repolarization variability independent of RR interval variability is of clinical interest. It has been linked to direct autonomic nervous system (ANS) regulation of the ventricles in healthy subjects and seems to reflect the instability of the ventricular repolarization process in heart disease. In this study, we sought to identify repolarization measures that best reflect the sympathetic influences on the ventricles independent of the RR interval. ECG was recorded in 46 young subjects during supine and then following 45 degrees head-up tilt. RR intervals and five repolarization features (QTend, QTpeak, RTend, RTpeak, and TpTe) were extracted from the ECG recordings. Repolarization variability was separated into RR-dependent and RR-independent variability using parametric spectral analysis. Results show that LF power of TpTe is independent of RR in both supine and tilt, while the LF power of QTend and RTend independent of RR and respiration increases following tilt. We conclude that TpTe is independent of RR and is highly affected by respiration. QTend and RTend LF power might reflect the sympathetic influences on the ventricles elicited by tilt. Graphical abstract.

The relationship between the surface electrocardiogram (ECG) T wave to intracardiac repolarization is poorly understood.
The purpose of this study was to examine the association between intracardiac ventricular repolarization and the T wave on the body surface ECG (SECGTW).
Ten patients with a normal heart (age 35 ± 15 years; 6 men) were studied. Decapolar electrophysiological catheters were placed in the right ventricle (RV) and lateral left ventricle (LV) to record in an apicobasal orientation and in the lateral LV branch of the coronary sinus (CS) for transmural recording. Each catheter (CS, LV, RV) was sequentially paced using an S1-S2 restitution protocol. Intracardiac repolarization time and apicobasal, RV-LV, and transmural repolarization dispersion were correlated with the SECGTW, and a total of 23,946 T waves analyzed.
RV endocardial repolarization occurred on the upslope of lead V1, V2, and V3 SECGTW, with sensitivity of 0.89, 0.91, and 0.84 and specificity of 0.67, 0.68, and 0.65, respectively. LV basal endocardial, epicardial, and mid-endocardial repolarization occurred on the upslope of leads V6 and I, with sensitivity of 0.79 and 0.8 and specificity of 0.66 and 0.67, respectively. Differences between the end of the upslope in V1, V2, and V3 vs V6 strongly correlated with right to left dispersion of repolarization (intraclass correlation coefficient 0.81, 0.83, and 0.85, respectively; P <.001). Poor association between the T wave and apicobasal and transmural dispersion of repolarization was seen.
The precordial SECGTW reflects regional repolarization differences between right and left heart. These findings have important implications for accurately identifying biomarkers of arrhythmogenic risk in disease.

UNASSIGNED: The interval from the peak to the end of the T wave (Tp-Te) on electrocardiography is considered a marker of ventricular arrhythmias. A previous study suggested that right stellate ganglion block prolonged QT and QT dispersion (QTD). We investigated the effect of thoracic epidural sympathetic block with 1% mepivacaine on QT, QTD, Tp-Te, and Tp-Te/QT by using computerized measurement.
UNASSIGNED: After obtaining the approval of the ethics committee of Dokkyo Medical University Hospital, 23 patients with American Society of Anesthesiologists physical status I or II who were scheduled to undergo thoracic surgery were enrolled. An epidural catheter was inserted at the Th4-5 or 5-6 level and then used for injection of 7 mL of 1% mepivacaine. Changes in RR interval, QT, corrected QT (QTc), QTD, QTc dispersion (QTcD), Tp-Te, Tp-Te/QT, and Tp-Te/QTc before and after epidural injection were assessed by computerized measurement. Statistical analysis was performed by one-way ANOVA.
UNASSIGNED: Systolic blood pressure was consistently suppressed 10-15 minutes after injection (baseline: 136±10 mmHg, 11 minutes: 113±12 mmHg, 12 minutes: 112±13 mmHg, 13 minutes: 112±12 mmHg, 14 minutes: 108±17 mmHg, 15 minutes: 111±14 mmHg; P<0.05). However, RR interval, QT, QTc, QTD, QTcD, Tp-Te, Tp-Te/QT, and Tp-Te/QTc were not changed after epidural block.
UNASSIGNED: Thoracic epidural injection of 1% mepivacaine did not alter QT, QTc, QTD, QTcD, Tp-Te, Tp-Te/QT, or Tp-Te/QTc. These results emphasize the safety of thoracic epidural sympathetic block with 1% mepivacaine for patients compared with right stellate ganglion block, in terms of cardiac repolarization.

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UNASSIGNED: To examine the relationship between Tpeak- Tend interval (Tpe) and Tpe/QT ratio with occurrence of ventricular premature beats (VPBs) and left ventricular remodeling in hypertension.
UNASSIGNED: A total of 52 patients with mild to moderate essential hypertension were included, undergoing echocardiography and 24-hours Holter monitoring. Ventricular remodeling was assessed by left ventricular mass index (LVMI) using the Devereux formula and diastolic function by transmitral E and A wave velocities and E/A ratio. Tpe was measured in the precordial leads. The end of the T wave was set by the method of the tangent to the steepest descending slope of the T wave.
UNASSIGNED: Tpe and Tpe/QT in leads V2 (r = 0.33, P = 0.01; r = 0.27, P = 0.04 respectively) and V3 (r = 0.40, P = 0.002; r = 0.40, P = 0.003, respectively) correlated significantly with LVMI. A significant inverse relationship was observed between E/A ratio and QT (r = -0.33, P = 0.01), Tpe in V3 (r = -0.39, P = 0.003) and Tpe/QT in V3 (r = -0.31, P = 0.02). Tpe in V3, V5, mean Tpe and maximum Tpe with cut-off values of 60 ms, 59 ms, 62 ms and 71 ms, respectively, associated with the occurrence of ventricular premature beats.
UNASSIGNED: The repolarization parameters Tpe interval and Tpe/QT ratio correlate with LVMI and indices of left ventricular diastolic function and show better predictive values than traditional parameters such as QT interval and QT dispersion. Lead V3 is the best lead for measuring Tpe and Tpe/QT. These ECG indices can therefore be used in clinical practice to monitor LV remodeling and predict occurrence of VPBs.