Tpeak-Tend Interval Research Articles

Magnetocardiographic imaging of Tpeak-Tend magnetic field dynamics discriminates between ventricular repolarization disorders due to mitral valve prolapse and to ischemic heart disease

Abstract Background Several etiopathogenetic mechanisms, including ischemia of the papillary muscles, abnormal catecholamine regulation, baroreflex modulation, and activation of atrial natriuretic peptide induced by abnormal stretch of the prolapsing mitral leaflets, have been suggested as possible causes of ventricular repolarization abnormalities (VRab) in patients (pts) with mitral valve prolapse (MVP) [1-3], especially in those with chest pain (CP). Purpose Since magnetocardiography (MCG) is a sensitive alternative to improve the detection of VRab, this study aimed to evaluate its discrimination accuracy to differentiate VRab due to MVP from those due to ischemic heart disease (IHD). Methods MCG recordings of 32 female patients (age 40.3±13.3 years) with MVP (at echocardiography), 20 of them with CP and/or palpitations, were retrospectively compared with those of 35 pts with IHD (at least one vessel stenosis >70%) (age 66.2±10.6 years), and with those of 32 age-matched (age 40.8±11.5 years) healthy females (HF) without MVP. The cardiac magnetic field (MF) component perpendicular to the anterior chest wall (Bz) was recorded with a 36-channel DC-SQUID MCG system (sensitivity ~30 fT/VHz). Thirteen MCG parameters, five derived from the analysis of the T-wave MF extrema dynamics, and eight from the effective magnetic vector (EMV) dynamics, were automatically calculated with proprietary software during the Tpeak-Tend interval (T3-T4 in Figure 1). Discriminant analysis (DA) was applied to separate groups. Results At univariate analysis, 11 MCG parameters were significantly different (p< 0.05) between MVP and IHD pts (Table 1). After multivariate analysis, 9 parameters (AzimuthMeanA, TrajectoryLengthRangeD, AngleDerivativeRangeD, AzimuthdiffAD, Q2AnalysisScore, AngleMinimum, AngleDynamics, DistanceDynamics, RatioDynamics) differentiated MVP and IHD pts’ VRab with 80% accuracy (cross-correlated), at DA. Moreover, in IHD pts abnormality of EMV dynamics extended also along the whole T-wave [4]. Three EMV parameters of the Tpeak-Tend interval (TrajectoryLengthRangeD, AzimuthdiffAD, Q2AnalysisScore), and three T-wave MF extrema parameters (AngleMinimum, Distance Dynamics, and Ratio Dynamics) were abnormal in 11 MVP pts, 10 of them with CP but normal ECG, and only one asymptomatic. Discussion: MCG EMV and MF dynamics calculated from rest-MCG data are reliable to identify VRab in pts with MVP and with IHD, differentiating them with a good discrimination accuracy. MCG VRa abnormality was mostly confined in the Tpeak-Tend interval in pts with MVP (in agreement with previous ECG findings [5]), while extended to the whole ST interval in IHD pts. Rest MCG is more sensitive than ECG in detecting VRab in pts with MVP and CP. Due to the limited number of investigated cases, the potential arrhythmogenicity of MVP-related VRab detected with MCG was not evaluated.Figure 1.MCG imaging of Tpeak-Tend MFTable 1

Analysis of ventricular repolarization parameters and heart rate variability in obesity: a comparative study

Obesity is associated with dysfunctional electrocardiographic and cardiac autonomic parameters, which may lead to increased cardiovascular morbidity. Novel electrocardiographic repolarization markers such as Tpeak-Tend (Tpe) interval have not yet been deeply studied in obese patients. We aimed to investigate the association between ventricular repolarization parameters and heart rate variability (HRV) and how they are affected by changes occurring in the cardiac autonomic nervous system. Ninety subjects categorized by Southeast Asian BMI (kg/m2) standards - normal (18-22.9), overweight (23-24.9), and obese (> 24.9), underwent assessment of ventricular repolarization parameters and HRV. Linear correlation between different parameters was also conducted. Obese subjects exhibited longer QTc and Tpe intervals compared to normal-weight subjects (p-value < 0.001, 0.026 respectively). The QTc interval showed a significant correlation (p < 0.05) with all HRV parameters by linear correlation, while the Tpe interval did not. Anthropometric parameters (BMI, WC, and WHR) were also correlated to both ventricular repolarization variables and HRV. While changes in the QTc interval may be due to obesity and/or autonomic changes occurring in the obese state, the Tpe interval does not show a relation with autonomic parameters. Thus, implicating that a change in the Tpe interval is primarily due to the direct effect of either cardiac or visceral obesity. The observed associations between ECG parameters, obesity indices, and HRV parameters suggest a role for ECG in screening for cardiovascular morbidity.

Association of transmural dispersion of ventricular repolarization (Tpeak-Tend interval) with components of metabolic syndrome: data from the ESSE-RF3

Aim. To study the associations of the Tpeak-Tend interval (TpTe) with components of metabolic syndrome (MS) in a sample of Novosibirsk residents.Material and methods. The study included 1042 residents of Novosibirsk (510 (48,9%) men) aged 35-74 years. The examination included the collection of demographic and social data, anthropometry, blood pressure (BP) measurement, and electrocardiography (ECG). MS was determined according to the 2013 criteria. The TpTe interval from the peak, as the maximum positive or negative T wave deviation, to the end of the T wave, was measured manually in lead V5. The corrected TpTe (cTpTe) interval was used in the study.Results. The cTpTe is inversely associated with female sex (B 3,390, 95% confidence interval (CI): (-5,516-2,504), p=0,001). The cTpTe interval is associated with a blood pressure (BP) ≥140/90 mm Hg (B 3,154, 95% CI: (1,614-4,688), p=0,001), low-density lipoprotein cholesterol (LDL-C) &gt;3,0 mmol/l (B 1,818, 95% CI: (0,409-3,544), p=0,030), regardless of other MS components, sex and age. The cTpTe interval was higher in individuals with BP ≥140/90 mm Hg compared with individuals with BP &lt;140/90 mm Hg (69,08 95% CI: 67,59-70,66 vs 65,93 95% CI: 64,60-67,24; p=0,001), and in persons with LDL-C &gt;3,0 mmol/l (68,41 95% CI: 67,11-69,63 vs 66,60 95% CI: 65,02-68,23; p=0,023), compared with individuals with LDL-C &lt;3,0 mmol/l.Conclusion. The cTpTe interval, considered as an indicator of transmural dispersion of ventricular repolarization, is shorter in women than in men and is associated with hypertension and atherogenic dyslipidemia, regardless of other MS components.

The Effect of Obesity on Repolarization and Other ECG Parameters.

Background: Overweight and obesity are important risk factors in the development of cardiovascular diseases. New repolarization markers, such as the Tpeak-Tend interval and JTpeak intervals, have not yet been profoundly studied in obese patients. The study aims to analyze whether, in patients with obesity and overweight, repolarization markers, including the Tpeak-Tend interval, are prolonged and simultaneously check the frequency of other ECG pathologies in a 12-lead ECG in this group of patients. Methods: A study group consisted of 181 adults (90 females and 91 males) with overweight and first-class obesity. The participants completed a questionnaire, and the ECG was performed and analyzed. Results: When analyzing the classic markers, only QT dispersion was significantly higher in obese people. The Tpeak-Tend parameter (97.08 ms ± 23.38 vs. 89.74 ms ± 12.88, respectively), its dispersion, and JTpeak-JTend parameters were statistically significantly longer in the obese group than in the controls. There were also substantial differences in P-wave, QRS duration, and P-wave dispersion, which were the highest in obese people. Tpeak-Tend was positively correlated with body mass and waist circumference, while JTpeak was with BMI, hip circumference, and WHR. Tpeak/JT was positively correlated with WHR and BMI. In backward stepwise multiple regression analysis for JTpeak-WHR, type 2 diabetes and smoking had the highest statistical significance. Conclusions: Only selected repolarization markers are significantly prolonged in patients with class 1 obesity and, additionally, in this group, we identified more pathologies of P wave as well as prolonged QRS duration.

Time-dependent activation and repolarization changes following left bundle branch area pacing versus conventional biventricular pacing in patients with dyssynchronous heart failure

Abstract Background Cardiac Resynchronization Therapy (CRT) is the standard treatment for patients with dyssynchronous heart failure. Despite the effectiveness of conventional biventricular pacing (BiVP), 6-16% of patients develop ventricular tachyarrhythmias (VTAs) within a year of implantation. The relationship between BiVP and the development of VTAs is still under debate. During BiVP, the left-sided epicardium-to-endocardium activation creates a non-physiological activation and hence a non-physiological repolarization, which might trigger VTAs. A novel alternative treatment option to BiVP that on the contrary induces a left ventricular endocardium-to-epicardium activation, is left bundle branch area pacing (LBBAP). We hypothesized that LBBAP leads to a more homogenous repolarization than conventional BiVP. Purpose To compare time-dependent activation and repolarization changes in patients with dyssynchronous heart failure receiving LBBAP versus BiVP. Methods Patients eligible for CRT who underwent LBBAP (n=21) or BiVP (n=94) were retrospectively included. Standard 12-lead electrocardiograms obtained prior to implantation [baseline], shortly following implantation (0-2 days, [acute phase]), and after prolonged pacing during follow-up (31-180 days, [chronic phase]) were analyzed. QRS duration and QRS area were calculated through reconstruction of the vectorcardiogram and further analyzed together with corrected QT (QTc) and corrected Tpeak-Tend (Tp-e,c) intervals using a semi-automatic approach in MATLAB. Differences between LBBAP and BiVP patients were determined using the Mann-Whitney U-test. Time-dependent changes within groups were determined using the Wilcoxon signed-rank tests. Significance was defined as a p-value ≤0.05. Results (see figure): Compared to baseline, QRS duration and QRS area decreased significantly during the acute phase (both p &amp;lt; 0.01) and stabilized during chronic pacing for both BiVP and LBBAP patients. Differences in QRS duration or QRS area between LBBAP and BiVP were not significant at any of the time points. In the acute phase, BiVP resulted in a temporary and significant prolongation of both QTc and Tp-e,c compared to baseline (both p &amp;lt; 0.01). However, there was a subsequent shortening observed between the acute and chronic phases for both QTc and Tp-e,c (both p &amp;lt; 0.01). Compared to baseline, LBBAP acutely shortened Tp-e,c (p = 0.02) and tended to shorten QTc. During chronic pacing, LBBAP shortened QTc and Tp-e,c compared to baseline (p = 0.01 and p &amp;lt; 0.01). The decreases in QTc and Tp-e,c were larger in LBBAP than in BiVP patients in the acute and chronic pacing phase (all p &amp;lt;0.01). Conclusion CRT induces activation changes in both BiVP and LBBAP patients to a comparable extent. While BiVP leads to an acute increase in repolarization dispersions, LBBAP reduces markers of repolarization dispersion compared to baseline. The diminished dispersion of repolarization might contribute to an antiarrhythmic effect with LBBAP.

Relationship of the T-wave Tpeak-Tend interval with conduction system disorders in arterial hypertension

Relationship of the T-wave Tpeak-Tend interval with conduction system disorders in arterial hypertension

Tpeak-Tend ECG Marker in Obesity and Cardiovascular Diseases: A Comprehensive Review.

Globally, cardiovascular diseases are still the leading cause of death. Numerous methods are used to diagnose cardiovascular pathologies; there is still a place for straightforward and noninvasive techniques, such as electrocardiogram (ECG). Depolarization and repolarization parameters, including QT interval and its derivatives, are well studied. However, the Tpeak-Tend interval is a novel and promising ECG marker with growing evidence for its potential role in predicting malignant arrhythmias. In this review, we discuss the association between the Tpeak-Tend interval and several cardiovascular diseases, including long QT syndrome, cardiomyopathies, heart failure, myocardial infarction, and obesity, which constitutes one of the risk factors for cardiovascular diseases.

Tpeak-Tend Interval and its Derivatives as Indices of Repolarization Dispersion and Arrhythmic Risk: Traditional Review

Tpeak-Tend Interval and its Derivatives as Indices of Repolarization Dispersion and Arrhythmic Risk: Traditional Review

Effect of Flecainide and Ibutilide Alone and in Combination to Terminate and Prevent Recurrence of Atrial Fibrillation.

There is a need for improved approaches to rhythm control therapy of atrial fibrillation (AF). The effectiveness of flecainide (1.5 µmol/L) and ibutilide (20 nmol/L), alone and in combination, to cardiovert and prevent AF recurrence was studied in canine-isolated coronary-perfused right atrioventricular preparations. We also examined the safety of the combination of flecainide (1.5 µmol/L) and ibutilide (50 nmol/L) using canine left ventricular wedge preparations. Sustained AF (>1 hour) was inducible in 100%, 60%, 20%, and 0% of atria in the presence of acetylcholine alone, acetylcholine+ibutilide, acetylcholine+flecainide, and acetylcholine+ibutilide+flecainide, respectively. When used alone, flecainide and ibutilide cardioverted sustained AF in 40% and 20% of atria, respectively, but in 100% of atria when used in combination. Ibutilide prolonged atrial and ventricular effective refractory period by 15% and 8%, respectively, at a cycle length of 500 ms (P<0.05 for both). Flecainide increased the effective refractory period in atria by 27% (P<0.01) but by only 2% in the ventricles. The combination of the 2 drugs lengthened the effective refractory period by 42% in atria (P<0.01) but by only 7% (P<0.05) in the ventricles. In left ventricular wedges, ibutilide prolonged QT and Tpeak-Tend intervals by 25 and 55%, respectively (P<0.05 for both; cycle length, 2000 ms). The addition of flecainide (1.5 µmol/L) partially reversed these effects (P<0.05 for both parameters versus ibutilide alone). Torsades de Pointes score was relatively high with ibutilide alone and low with the drug combination. In our experimental model, a combination of flecainide and ibutilide significantly improves cardioversion and prevents the recurrence of AF compared with monotherapies with little to no risk for the development of long-QT-mediated ventricular proarrhythmia.

Assessment of repolarization dispersion by using endocardial unipolar electrograms in patients with brugada syndrome and spontaneous coved-type electrocardiographic pattern

Abstract Background Coved-type electrocardiographic (ECG) pattern of patients with Brugada syndrome (BrS) is secondary to action potential lengthening in the right ventricular outflow tract (RVOT) epicardium. This may be approximated by activation-recovery interval (ARI), a marker of local repolarization dispersion. Purpose Our aim was to examine epicardial repolarization dispersion by ARI in the RVOT in patients with BrS and its correlation with conduction slowing and Tpeak-Tend (Tpe) interval, a marker of altered repolarization on surface ECG previously associated with a higher arrhythmic risk in this setting. Methods 24 patients with coved-type BrS phenotype underwent an invasive electrophysiological evaluation with endocardial high-density 3D mapping and programmed ventricular stimulation (PVS). Mapping data was exported and converted into MatLab format using OpenEP. Paraview was used to select a region of interest (ROI) specifically comprising of sub-pulmonary RVOT and RV free wall. ARI was calculated for each point of the ROI using a semi-automated algorithm with the Wyatt method and corrected with the Bazett formula (ARIc). The values were then interpolated to create ARI maps. For each patient, we calculated the value of ARIc at 75% of the distribution (ARIcQ3) and mean ARI for the values in the interval above ARIcQ3 (meanARIcQ3); ARIcQ3 points were also used to create maps. Activation maps were used to determine right ventricular activation time (RVAT). Tpe intervals were calculated with the tangent method on V1, V2 and V3 of 20 low-noise sinus beats recorded during the procedure, and then corrected with the Bazzett formula. Results Out of 24 patients, 6 had inducible VT/ VF during PVS (PVS+) while 18 did not (PVS-). Average ARI, ARIc, ARIcQ3, and meanARIcQ3 were 291.4 ± 22.1 ms; 306.0 ± 27.3 ms; 335.1 ± 28.3 ms; 353.1 ± 30.3 ms, respectively. Average Tpe was 75.0 ± 7.3 ms, with a mean corrected Tpe of 79.0 ± 10 ms. Mean RVAT was 111.9 ± 30.7 ms. Zones with ARIcQ3 were all located into the anterior and subpulmonary RVOT. We found a correlation between ARIcQ3 and mean corrected Tpe (R=0.58, p=0.003), and between meanARIcQ3 and mean corrected Tpe (R=0.65, p&amp;lt;0.001). A good correlation was also found between ARIcQ3 and RVAT (R=0.5441, p=0.009), and meanARIcQ3 and RVAT (R=0.49, p=0.02). No significant differences were found between PVS+ and PVS- patients. Conclusions Our results show the presence of zones with long ARI within RVOT of BrS with type-1 phenotype, indicating marked local repolarization dispersion. Longer ARIs correlate with altered repolarization on surface ECG and with prolongation of local activation time. ARI mapping can help identify repolarization dispersion and should be evaluated in the setting of a multi-parametric risk assessment in BrS with spontaneous coved-type ECG.

Effect of Remifentanil on the Tpeak-Tend Interval During Electroconvulsive Therapy.

QT interval dispersion, which reflects the regional heterogeneity of ventricular repolarization, increases during electroconvulsive therapy (ECT). Tpeak-Tend (TpTe) is considered a new marker of the transmural dispersion of ventricular repolarization (TDR). This study aimed to evaluate the effect of remifentanil on TpTe during ECT. Forty-two patients who were scheduled to undergo ECT with American Society of Anesthesiologists physical status I or II randomly received 0.1μg/kg remifentanil (group R: n = 21) or saline (group C: n = 21). After the induction of general anesthesia, we measured the TpTe, TpTe/QT, TpTe/QTc, TpTe/RR, TpTe/√RR and TpTe/3√RR every minute during ECT (QT: QT interval, QTc: corrected QT interval, RR: RR interval). Statistical analysis was performed using two-way analysis of variance (ANOVA). Immediately (T0) and 1min (T1) after electrical stimulation, the RRs (group C: T0; 654.2 ± 145.9ms, T1; 657.3 ± 114.8ms, group R: T0; 849.6 ± 249.3ms, T1; 885.4 ± 213.6ms, p < 0.05) were significantly increased, while systolic (group C: T0; 177.1 ± 35mmHg, group R: T0; 129 ± 27.2mmHg, p < 0.05) and diastolic blood pressures (group C: T0; 107.1 ± 22.4mmHg, T1; 101.3 ± 23.2mmHg, group R: T0; 75.4 ± 19.3mmHg, T1; 80.6 ± 18.3mmHg, p < 0.05) were significantly decreased in group R compared to group C. The TpTe/RR was significantly lower at T1 in group R compared to group C (group C: 101.5 ± 28.2, group R: 76.8 ± 21.8, p < 0.05). However, there was no significant difference in TpTe, TpTe/QT, TpTe/QTc, TpTe/√RR or TpTe/3√RR between the two groups throughout the study. Pretreatment with remifentanil suppressed the increase of TpTe/RR after electrical stimulation. Our results imply that remifentanil may lead to a decrease in TDR during ECT. This trial was registered with the University Hospital Medical Information Network (registration number: UMIN000051958).

Action potential morphology affects T-wave symmetry (simulation study)

BackgroundAssessing T-wave symmetry in addition to QT subintervals measurements can provide novel independent data about ventricular repolarization abnormalities linked with arrhythmogenesis. However, the causes of the changes of T-wave symmetry are not completely understood. In silico studies showed that the more symmetrical T-waves were associated with shorter action potential duration (APD) and larger dispersion of ventricular repolarization (DOR). The aim of present simulation was to study the association between T-wave symmetry and action potential (AP) shape. MethodsECGs were simulated using a cellular automata model shaped as a ventricular wall segment, and two biophysically-detailed models of ventricular AP – the rabbit and the human. The symmetry ratio (SR) was calculated as a T-wave onset-peak to peak-end area ratio. The individual and combined effects of APD, DOR and AP shape on SR were simulated. To study the effect of AP shape, different APs from triangulated to rectangular were simulated. ResultsThe simulations showed that AP shape along with APD and DOR contributes much to T-wave symmetry. APs with a flat phase 3 (triangulated) produced asymmetrical T-waves (SR ≥ 1.5) in all simulations, except the shortest APD range. APs with a rapid phase 3 (rectangular) were associated with more symmetrical T-waves (SR ≤ =1) both at the short and the long APDs. ConclusionSR marker in combination with the standard ECG parameters (QT interval, Tpeak-Tend interval) may be useful to identify the proarrhythmic triangulated AP shape.

Evaluation of the effects of insulin resistance on ECG parameters in obese children.

Obese people are at increased risk of arrhythmia and sudden death, even in the absence of heart dysfunction. Increased insulin resistance, neurohumoral and autonomic changes in obesity can cause atrial and ventricular repolarization abnormalities. This study aimed to investigate the effect on ventricular repolarization parameters and to show the increased risk of ventricular arrhythmia in obese children. The data of 50 obese children aged 2-18 who applied to the Pediatric Endocrinology Outpatient Clinic were evaluated prospectively. In 12-lead ECGs, heart rate, Pmax, Pmin, P-wave dispersion (Pwdisp), QTmax, QTmin, QT dispersion (QTd), QTcmax, QTcmin, QTc interval dispersion (QTcd), Tpeak-Tend interval (Tp-e), Tp-e/QT, Tp-e/QTc were calculated electronically. Tp-e time (0.041 ± 0.004/0.049 ± 0.015/p=0.018) and Tp parameters were measured in obese children with and without insulin resistance. Tp-e/QT ratio was also found to be high (p=0.035). There is a negative correlation between BMI SDS values and QTcmax and QTcmin values in patients with insulin resistance (p=0.015). In our study, the Tp-e interval and Tp-e/QT ratios, which had been revealed in literature to be more sensitive in demonstrating ventricular arrhythmias, were found to be higher in obese individuals with insulin resistance than in those without insulin resistance. Obese individuals with or without insulin resistance should be carefully evaluated in terms of atrial and ventricular depolarization and repolarization parameters with 12-lead ECG during their outpatient controls, and annual 24-hour Holter control should be performed to detect arrhythmias.

Multifactorial model for prediction of the development of polymorphic ventricular tachycardia in patients with drug-induced QT interval prolongation induced by class III antiarrhythmic drugs

Aim. To develop a multifactorial model for predicting the development of polymorphic ventricular tachycardia (VT) in patients with drug-induced long QT syndrome (LQTS) induced by class III antiarrhythmic drugs (AADs) by identifying electrocardiographic, laboratory and molecular genetic predictors.Methods. The study included 64 patients (37 (57.9%) women and 27 (42.1%) men, mean age 57.2±9.4 years) with ischemic heart disease and/or arterial hypertension. and cardiac arrhythmias, in which drug-induced prolongation of the QTc interval (Bazett) (over 450 ms in men and over 470 ms in women) was noted with the use of class III AADs (amiodarone or sotalol) in a cardiac hospital. Depending on the presence or absence of non-sustained polymorphic VT according to 24-hour ECG Holter monitoring, patients were further divided into two groups: 17 patients with episodes of non-sustained polymorphic VT and 47 patients without such episodes. All patients underwent clinical and laboratory, instrumental and molecular genetic studies, which included taking an anamnesis, recording ECG in 12 leads, biochemical blood test, determining the levels of neuronal NO-synthase (NOS1) and the adapter protein of neuronal NO-synthase (NOS1AP) in blood serum by enzyme immunoassay, determination of nitric oxide synthase gene polymorphisms by polymerase chain reaction. To assess the relationship of the studied parameters with the achievement of the end point, the method of logistic regression with a binary response and the logit function of the connection was used.Results. To assess the risk of developing non-sustained polymorphic VT in patients with drug-induced LQTS while taking class III AADs, a complex binary logistic regression model was developed, including the following indicators: patient gender (p=0.019), relative variance of the QT interval (p=0.002), duration of the Tpeak-Tend interval, (p=0.034), serum magnesium (p=0.004) and NOS1 (p=0.004) levels, as well as the AA genotype of the G84A polymorphism of the NOS1 gene (p=0.049). With the calculated value of the threshold probability p≥0.48, the developed model makes it possible to identify patients at high risk of developing polymorphic VT in patients with drug-induced LQTS with a sensitivity of 94.12%, a specificity of 89.36%, and an area under the ROC curve of 0.977 (0.95-1.0, p&lt;0.001).Conclusion. The developed complex model will allow predicting the risk of proarrhythmic effects in patients with drug-induced LQTS, which will lead to a decrease in the number of cardiovascular events in this category of patients.

Repolarization changes following left bundle branch area pacing versus conventional biventricular pacing in patients with dyssynchronous heart failure

Abstract Funding Acknowledgements Type of funding sources: Foundation. Main funding source(s): Dutch Heart Foundation. Background Biventricular pacing (BiVP) is the standard treatment for patients with dyssynchronous heart failure. Despite the effectiveness of BiVP, 6% of patients develop ventricular tachyarrhythmia’s (VTAs) within one year following implantation. The relationship between BiVP and the development of VTAs is still under debate. The left-sided epicardium-to-endocardium activation during BiVP creates a nonphysiological activation and repolarization and might provoke VTAs. A relatively new treatment option is left bundle branch area pacing (LBBAP), in which the physiological activation of the left ventricle is restored. We hypothesize that LBBAP leads to a more homogenous repolarization compared to conventional BiVP. Purpose To compare time-dependent repolarization changes in patients with dyssynchronous heart failure receiving LBBAP versus BiVP. Methods Patients with dyssynchronous heart failure eligible for cardiac resynchronization therapy who underwent LBBAP (n=13) or BiVP (n=28) were retrospectively included. Standard 12-lead electrocardiograms (ECG) obtained prior to implantation [baseline], shortly following implantation (0-2 days,[acute]) and during follow-up (31-180 days, [FU]) were analyzed. The QT interval and Tpeak to Tend interval (Tpeak-Tend) were calculated using a semi-automatic approach in MATLAB. Repolarization differences between LBBAP and BiVP patients were determined using the Mann-Whitney U-test. Time-dependent changes within groups were determined using the Wilcoxon signed rank tests. Significance was defined as a p-value ≤0.05. Results The QT interval did not significantly change over time in BiVP patients, but it decreased immediately following implantation and during FU in LBBAP patients. At FU, QT interval was significantly lower in LBBAP than in BiVP patients (Figure 1, left panel). A slight increase in Tpeak-Tend interval over time in BiVP patients, while it tends to decrease over time in LBBAP patients can be seen in the right panel. Acutely and long term after implantation, Tpeak-Tend was significantly lower in LBBAP than in BiVP patients. Conclusion LBBAP is associated with lower QT and Tpeak-Tend intervals compared to BiVP during FU, suggesting that LBBAP leads to less heterogeneity of repolarization over time. These findings suggest a more physiological repolarization pattern in LBBAP compared to BiVP, which may decrease the risk of developing VTAs.

Evaluation of the Tpeak-Tend Interval as an Arrhythmogenicity Index in Graves' Disease

Introduction.Graves’ disease is the most common cause of hyperthyroidism. The mortality rate increases by 20% in hyperthyroid patients; cardiac problems are the leading cause of death and arrhythmia is the most common cardiac complication.&#x0D; Our study aimed to evaluate the corrected QT interval (QTc), the Tpeak-Tend interval (Tp-e), and the Tp-e/QTc ratio to predict arrhythmia risk in patients with Graves’ disease.&#x0D; Methods. The study included 64 patients with Graves’ disease and 57 euthyroid controls. The 12-lead electrocardiograms of the individuals under study were evaluated. The QTc interval, the Tp-e interval, and the Tp-e/QTc ratio of all participants were determined and statistically evaluated with thyroid stimulating hormone (TSH), free triiodothyronine (fT3) and free thyroxine (fT4) values.&#x0D; Results. Tp-e (p &lt; 0.001) and QTc (p &lt; 0.05) were significantly prolonged in the group of patients with Graves’ disease as compared to the control group. Heart rate was higher in patients with Graves’ disease as well (p &lt; 0.05). Correlation analysis in patients with hyperthyroidism demonstrated that Tp-e (r=0.372, p=0.002), QTc (r=0.291, p=0.020), and fT3 levels were significantly and positively correlated. Similarly, Tp-e (r=0.271, p=0.030), QTc (r=0.259, p=0.039), and fT4 levels were significantly and positively correlated.&#x0D; Conclusions. We observed a significant prolongation of the Tp-e and QTc intervals with the increase in fT3 and fT4 levels. On the other hand, our study demonstrated that the sensitivity and specificity of Tp-e in the prediction of hyperthyroidism were 70.3% and 70.1%, respectively (AUC=0.724 (CI: 0.629-0.818)), the optimal cut-off value=83.5 ms). The Tp-e interval, which has recently been used as one of the arrhythmogenicity indices, may be an indicator of arrhythmia risk in patients with Graves’ disease.

C23 ELECTROCARDIOGRAPHIC PREDICTORS OF PRIMARY VENTRICULAR FIBRILLATION DURING A FIRST ACUTE MYOCARDIAL INFARCTION

Abstract Introduction Few small studies evaluated electrocardiographic (ECG) predictors of ventricular fibrillation (VF) before reperfusion during a first acute myocardial infarction (AMI). None accounted for the time between symptom onset and ECG. Objectives To evaluate the ECG predictors of primary VF in the PREDESTINATION (PRimary vEntricular fibrillation and suDden dEath during a firST myocardIal iNfArcTION) population. Patients and methods: PREDESTINATION is an ongoing, prospective, multicenter, case–control study (1:2 match for sex and age) enrolling patients aged 18–80 with a first AMI, whether complicated (cases) or not (controls) by primary VF before reperfusion. For the present analysis, we matched 1:1 for age, sex, infarct site, and symptom–ECG time, the ECGs of cases before VF and those of controls revascularized at least 60 minutes after symptom onset. ECG traces were digitized in pdf and enlarged by 400%. Three blind analyzes were performed: on the entire population, on only anterior and only non–anterior AMI. Results PREDESTINATION currently includes 1478 patients (mean 59 years, 83% male), 533 of whom are cases. Among the cases, only 59 (58 ± 11 years, 10% females, 64% with anterior AMI, mean symptoms–ECG time 78±60 minutes, mean ECG–VF time 23±15 minutes) had a pre–VF ECG of adequate quality. Both in the general population (118 ECGs) and in anterior AMIs subgroup (76 ECGs), the presence of ventricular (VEB) or supraventricular ectopic beats (SVEB) was associated with an increased risk of developing VF (maximum OR 8.35 for VEBs in anterior AMIs). In the subgroup of anterior AMIs, the Tpeak–Tend interval in non–infarction leads, both corrected for the RR interval (Bazett) and for the QT interval (TpTe/QT) was significantly longer in cases compared to controls. A TpTe/QT ≥0.33 in non–infarction leads was associated with an OR of 4.6 (p=0.02) of developing VF. Conclusions the present analysis, aimed at identifying ECG predictors of primary VF, is the first to perform a rigorous case–control matching including symptom–ECG time. In addition to ectopic beats, a well–known marker and promoter of electrical instability, we identified, only for anterior AMIs, a single additional predictor (TpTe/QT), which correlates with an increased dispersion of repolarization and consequently of ventricular refractoriness.

Role of Surface Electrocardiography in Differentiation between Obstructive and Non-Obstructive Hypertrophic Cardiomyopathy.

Electrocardiography (ECG), as an easily accessible modality, is usually helpful in hypertrophic cardiomyopathy (HCM) diagnosis. The purpose of this study was to evaluate the role of ECG in differentiating between obstructive (OHCM) and non-obstructive (NOHCM) HCM. The present study is a cross-sectional analysis of HCM patients referred to our center between 2008 and 2017. The study variables included age, sex, clinical presentation, medications, and ECG characteristics including PR interval, QRS width, QTc duration, Tpeak-Tend interval, QRS axis, QRS transition, ventricular hypertrophies, atrial abnormalities, ST-T abnormalities, and abnormal Q waves. The HCM sample consisted of 200 patients (55% males; age 45.60±15.50 y) from our HCM database. We compared the clinical and ECG characteristics of 143 NOHCM patients with those of 57 OHCM patients. The OHCM group was significantly younger than the NOHCM group (age =41.7 vs 47.0 y; P=0.016). The initial clinical presentation was similar between the 2 forms (P>0.05), and palpitations were the dominant symptom. Baseline ECG intervals, including PR (155.6 vs 157.9 ms), QRS (82.5 vs 82.0 ms), and QTc (430.5 vs 433.0 ms), were similar (all Ps>0.050). There were no differences regarding baseline rhythm, atrial abnormalities, QRS transition, ventricular hypertrophies, axis changes, ST-T changes, and abnormal Q waves between the HCM groups (all Ps>0.05). The present study showed that standard 12-lead ECG had no role in distinguishing patients with the obstructive and non-obstructive forms of HCM.

Relationship of the T-wave Tpeak-Tend interval with conduction system disorders in arterial hypertension.

The Tpeak-Tend interval of the T wave has emerged as a new electrocardiographic marker of increased transmural dispersion of ventricular repolarization. We aimed to determine the presence of cardiac conduction system disorders in patients with systemic arterial hypertension (SAH) who have altered Tpeak-Tend interval of the T wave. The 67 patients with SAH were divided into two groups. Those with prolonged (≥ 77 ms) Tpeak-Tend intervals, 21 (31%) patients were in the study group. Those with normal (< 77 ms) Tpeak-Tend intervals, 46 (69%) patients were in the control group. Alteration of ventricular repolarization manifested as a prolongation of the Tpeak-Tend interval was detected by computerized electrocardiographic analysis tools. The median value of QRS complex duration was significantly wider in the study group as compared to the control group (110 ± 12 ms vs. 94 ± 8 ms p < 0.001). There was a significantly greater incidence of left anterior hemiblock in the study group (14% vs. 0% p < 0.04). The median value of the QTc interval was significantly greater in the study group (440 ± 26 vs. 422 ± 15 p < 0.01). There was a significantly greater incidence of patients with prolonged QTc interval in the study group (33% vs. 11% p < 0.02). The median value of the Tpeak-Tend interval was significantly greater in the study group (84 ± 5 ms vs. 65 ± 4 ms p < 0.001), as well as, the Tpeak-Tend/QTc ratio in the study group (0.19 ± 0.1 vs. 0.16 ± 0.1 p < 0.001). There is a significantly greater ventricular repolarization disorders and abnormalities of the cardiac conduction system in SAH patients who possess altered Tpeak-Tend interval of the T wave.

Time and Frequency Repolarization Domains in Elderly Candidates to Transcatheter Aortic Valve Replacement.

Aortic valve stenosis (AVS) is a well-known risk factor for sudden cardiac death. Therefore, some non-invasive, electrocardiographic markers are capable to stratify the risk of sudden death at rest and during light mental challenge [mini-mental state examination (MMSE) administration]. We compared short period RR, QT and Te intervals variability in 42 candidates to and 12 age-matched hypertensive control patients at rest and during mental challenge. At rest, AVS patients showed a higher QT standard deviation (sd), QT low frequency power (LF), QT High Frequency (HF), Tpeak-Tend intervals sd (Te sd) and Te HF than the control group. During mental challenge AVS group showed a decrease of RR mean and RR HF, expressed in normalized units (NU), and an increase of RR total power (TP), RR LF, RR LF NU, RR LF, HF ratio (LF/HF). During this same mental test, QT sd, QT LF, QT HF, Te sd, Te LF, Te HF, QT variability index (VI), TeVI, QT normalized variance (VN) were higher in AVS patients than the control group. During mental challenge Te LF (r:0.825, p<0.05) was significantly associated to: serum albumin (β:-0.473, p<0.001), MMSE (β:-0.267, p:0.038), diastolic blood pressure (β:-0.443, p:0.03) and cardiac index (β:-0.303, p:0.029). AVS patients showed temporal dispersion of ventricular repolarization phase, useful maker to individuate high risk patients. MMSE administration induced a sympathetic sinus activation and vagal deactivation in AVS subjects. Frailty and mental function influenced Te HF and Te LF.