Search

Background: In post-ST-segment elevation myocardial infarction (STEMI) patients, the indices of repolarization on electrocardiogram (ECG) have shown promise for the prediction of death and malignant arrhythmias. In our study, we analyzed prospectively, in patients with STEMI undergoing reperfusion therapy, the acute effects of the reperfusion on the Tpeak-Tend (TpTe) and its predictive value for 30-day mortality, ventricular arrhythmias, and heart failure. Materials and Methods: We studied 75 STEMI patients aged 18–80 years admitted to Nizam's Institute of Medical Sciences, Hyderabad, over 6 months. ECGs were taken before and 90 min after reperfusion. TpTe interval was measured before (pre-TpTe) and after reperfusion (post-TpTe). 24-h Holter monitoring was recorded within 72 h of reperfusion to look for any arrhythmias. Patients were followed up for a period of 30 days, and all the major adverse cardiac events (MACE) if any, were noted. Results: In the primary percutaneous transluminal coronary angioplasty (PTCA) group, the mean change in TpTe after intervention was 19.7 ± 16.7 ms, whereas in thrombolysis group, it was 10.7 ± 13.8; and the difference was statistically significant (P < 0.05), suggesting the superiority of primary PTCA compared to thrombolysis. When pre-TpTe interval was compared between who survived (69) and who succumbed (09), higher values were seen in patients who succumbed to death (115 ± 5.48) versus (88 ± 16.5) (P < 0.05). Pre-TpTe value of 105 had 100% sensitivity and 83% specificity in predicting mortality. Conclusion: Primary PTCA was superior to thrombolysis in reducing the TpTe interval and MACE events. The pre-TpTe interval could predict 30-day mortality and ventricular arrhythmias in the immediate and late period after revascularization in STEMI.

Background: Populations of in silico electrophysiological models of human cardiomyocytes represent natural variability in cell activity and are thoroughly calibrated and validated using experimental data from the human heart. The models have been shown to predict the effects of drugs and their pro-arrhythmic risks. However, excitation and contraction are known to be tightly coupled in the myocardium, with mechanical loads and stretching affecting both mechanics and excitation through mechanisms of mechano-calcium-electrical feedback. However, these couplings are not currently a focus of populations of cell models. Aim: We investigated the role of cardiomyocyte mechanical activity under different mechanical conditions in the generation, calibration, and validation of a population of electro-mechanical models of human cardiomyocytes. Methods: To generate a population, we assumed 11 input parameters of ionic currents and calcium dynamics in our recently developed TP + M model as varying within a wide range. A History matching algorithm was used to generate a non-implausible parameter space by calibrating the action potential and calcium transient biomarkers against experimental data and rejecting models with excitation abnormalities. The population was further calibrated using experimental data on human myocardial force characteristics and mechanical tests involving variations in preload and afterload. Models that passed the mechanical tests were validated with additional experimental data, including the effects of drugs with high or low pro-arrhythmic risk. Results: More than 10% of the models calibrated on electrophysiological data failed mechanical tests and were rejected from the population due to excitation abnormalities at reduced preload or afterload for cell contraction. The final population of accepted models yielded action potential, calcium transient, and force/shortening outputs consistent with experimental data. In agreement with experimental and clinical data, the models demonstrated a high frequency of excitation abnormalities in simulations of Dofetilide action on the ionic currents, in contrast to Verapamil. However, Verapamil showed a high frequency of failed contractions at high concentrations. Conclusion: Our results highlight the importance of considering mechanoelectric coupling in silico cardiomyocyte models. Mechanical tests allow a more thorough assessment of the effects of interventions on cardiac function, including drug testing. [ABSTRACT FROM AUTHOR]

Background: In post-ST-segment elevation myocardial infarction (STEMI) patients, the indices of repolarization on electrocardiogram (ECG) have shown promise for the prediction of death and malignant arrhythmias. In our study, we analyzed prospectively, in patients with STEMI undergoing reperfusion therapy, the acute effects of the reperfusion on the Tpeak-Tend (TpTe) and its predictive value for 30-day mortality, ventricular arrhythmias, and heart failure. Materials and Methods: We studied 75 STEMI patients aged 18-80 years admitted to Nizam's Institute of Medical Sciences, Hyderabad, over 6 months. ECGs were taken before and 90 min after reperfusion. TpTe interval was measured before (pre-TpTe) and after reperfusion (post-TpTe). 24-h Holter monitoring was recorded within 72 h of reperfusion to look for any arrhythmias. Patients were followed up for a period of 30 days, and all the major adverse cardiac events (MACE) if any, were noted. Results: In the primary percutaneous transluminal coronary angioplasty (PTCA) group, the mean change in TpTe after intervention was 19.7 ± 16.7 ms, whereas in thrombolysis group, it was 10.7 ± 13.8; and the difference was statistically significant (P < 0.05), suggesting the superiority of primary PTCA compared to thrombolysis. When pre-TpTe interval was compared between who survived (69) and who succumbed (09), higher values were seen in patients who succumbed to death (115 ± 5.48) versus (88 ± 16.5) (P < 0.05). Pre-TpTe value of 105 had 100% sensitivity and 83% specificity in predicting mortality. Conclusion: Primary PTCA was superior to thrombolysis in reducing the TpTe interval and MACE events. The pre-TpTe interval could predict 30-day mortality and ventricular arrhythmias in the immediate and late period after revascularization in STEMI. [ABSTRACT FROM AUTHOR]

Background: Populations of in silico electrophysiological models of human cardiomyocytes represent natural variability in cell activity and are thoroughly calibrated and validated using experimental data from the human heart. The models have been shown to predict the effects of drugs and their pro-arrhythmic risks. However, excitation and contraction are known to be tightly coupled in the myocardium, with mechanical loads and stretching affecting both mechanics and excitation through mechanisms of mechano-calcium-electrical feedback. However, these couplings are not currently a focus of populations of cell models.Aim: We investigated the role of cardiomyocyte mechanical activity under different mechanical conditions in the generation, calibration, and validation of a population of electro-mechanical models of human cardiomyocytes.Methods: To generate a population, we assumed 11 input parameters of ionic currents and calcium dynamics in our recently developed TP + M model as varying within a wide range. A History matching algorithm was used to generate a non-implausible parameter space by calibrating the action potential and calcium transient biomarkers against experimental data and rejecting models with excitation abnormalities. The population was further calibrated using experimental data on human myocardial force characteristics and mechanical tests involving variations in preload and afterload. Models that passed the mechanical tests were validated with additional experimental data, including the effects of drugs with high or low pro-arrhythmic risk.Results: More than 10% of the models calibrated on electrophysiological data failed mechanical tests and were rejected from the population due to excitation abnormalities at reduced preload or afterload for cell contraction. The final population of accepted models yielded action potential, calcium transient, and force/shortening outputs consistent with experimental data. In agreement with experimental and clinical data, the models demonstrated a high frequency of excitation abnormalities in simulations of Dofetilide action on the ionic currents, in contrast to Verapamil. However, Verapamil showed a high frequency of failed contractions at high concentrations.Conclusion: Our results highlight the importance of considering mechanoelectric coupling in silico cardiomyocyte models. Mechanical tests allow a more thorough assessment of the effects of interventions on cardiac function, including drug testing.

BackgroundElectrocardiogram (ECG) has proven to be useful for early detection of cardiac involvement in Anderson-Fabry disease (AFD); however, little evidence is available on the association between ECG alterations and the progression of the disease.Aim and MethodsTo perform a cross sectional comparison of ECG abnormalities throughout different left ventricular hypertrophy (LVH) severity subgroups, providing ECG patterns specific of the progressive AFD stages. 189 AFD patients from a multicenter cohort underwent comprehensive ECG analysis, echocardiography, and clinical evaluation.ResultsThe study cohort (39% males, median age 47 years, 68% classical AFD) was divided into 4 groups according to different degree of left ventricular (LV) thickness: group A ≤ 9 mm (n = 52, 28%); group B 10–14 mm (n = 76, 40%); group C 15–19 mm (n = 46, 24%); group D ≥ 20 mm (n = 15, 8%). The most frequent conduction delay was right bundle branch block (RBBB), incomplete in groups B and C (20%,22%) and complete RBBB in group D (54%, p

Objective: In recent years, there has been worldwide recognition of the problems associated with Human Immunodeficiency Virus (HIV) infection and Acquired Immune Deficiency Syndrome (AIDS). The prevalence of cardiovascular disease in the HIV-infected population is increasing. Repolarization abnormalities, the significant contributor to life-threatening arrhythmias and mortality, are the most frequent electrocardiographic changes in this population. This study aimed to evaluate the changes in Tp-e interval, Tp-e/QT and Tp-e/corrected QT (QTc) ratios, and traditional electrocardiographic features of electrical dispersion in adults infected with HIV.Subjects and Methods: A total of 235 participants were selected in the current study. The HIV group consisted of 85 subjects (median age 36 years [25-48], and the control group included 150 individuals (median age 39 years [27-51]). Tp-e interval, Tp-e/QT and Tp-e/QTc ratios were measured by the 12-lead electrocardiogram.Results: Tp-e interval, cTp-e interval, and Tp-e/QT and Tp-e/QTc ratios were significantly higher in HIV patients compared to the control group (p = 0.006, p = 0.004, p = 0.003, and p = 0.002, respectively). In correlation analysis, there was inverse correlation between the mean cTp-e interval and CD4 count and Tp-e/QTc ratios and CD4 count (r = - 0.407, p < 0.001, r = - 0.416, p < 0.001, respectively). Besides, there was correlation between the mean cTp-e interval and high-sensitivity C-reactive protein (hsCRP) and Tp-e/QTc ratios and hsCRP (r = 0.403, p = 0.001, r = 0.406, p = 0.001, respectively).Conclusion: Our study revealed that the cTp-e interval, Tp-e/QT and cTp-e/QT ratios were prolonged and correlated to the severity of the disease in HIV-infected patients. Our findings may shed light on the cTp-e interval and Tp-e/QTc ratio and lead to further studies showing a relationship with ventricular arrhythmias and mortality in HIV-infected individuals. [ABSTRACT FROM AUTHOR]

Abstract We report a case of transient ECG abnormalities (negative T waves in the inferior leads) associated with presyncope related to acute cannabis consumption; after a few hours the ECG returned normal. Although pathophysiological mechanisms are not clear, it might be hypothesize a mismatch between increased oxygen demand and decreased oxygen supply or a marked hyperactivation of the sympathetic nervous system.

Prompt diagnosis of acute ST segment elevation myocardial infarction (STEMI) by the initial ECG is important in order to perform an urgent coronary angiography as soon as possible and achieve successful revascularization, therewith improving mortality and morbidity. Several diseases and conditions can mimic an acute myocardial infarction (AMI) but may not benefit from a (percutaneous) revascularization strategy. This narrative clinical review will discuss the ECG features of some of the causes of nonischemic ST segment elevation to facilitate early recognition, prevent wrongful diagnosis and improve treatment outcomes. [ABSTRACT FROM AUTHOR]

Objective: Recent studies utilizing fetal magnetocardiography have demonstrated the efficacy of corrected QT interval (QTc) measurement for in utero diagnosis and prognosis of long QT syndrome, a leading cause of sudden death in early life. The objective of the study was to formulate and test a novel statistical estimation method to detect the end of the fetal T-wave and thereby improve the accuracy of fetal QT interval measurement. Methods: To detect the end of the T-wave, we apply a sequential composite hypothesis test to decide when the T-wave has returned to baseline. The method uses the generalized likelihood ratio test in conjunction with a low-rank spatiotemporal model that exploits the repetitive nature of cardiac signals. The unknown model parameters are determined using maximum likelihood estimation. Results: In realistic simulations, the detector was shown to be accurate to within 10 ms (95% prediction interval), even at noise-to-signal ratios as high as 6. When applied to real data from normal fetuses, the detector agreed well with measurements made by cardiologists ( $-$1.4 $\pm$ 6.9 ms). Conclusions: The method was effective and practical. Detector performance was excellent despite the continual presence of strong maternal interference. Significance: This detector serves as a valuable adjunct to traditional measurement based on subjective assessment. [ABSTRACT FROM PUBLISHER]

Background/aim: Myocarditis in the acute phase usually presents with sinus tachycardia but many other arrhythmias might be seen as well. In this study we aimed to investigate repolarization abnormalities in baseline ECG of patients with myocarditis for the first time. Materials and methods: Thirty patients diagnosed with myocarditis and 25 healthy age-matched controls were included. Two different cardiologists measured corrected QT (QTc), QT dispersion (QTd), QT peak (QTp), T wave peak to T wave end (TpTe), TpTe/QT ratio, and TpTe/QTc ratio in 12-lead ECG. Results: When compared with the control group, QTp (P: 0.021), QT (P: 0.003), TpTe (P < 0.001), TpTe/QTc ratio (P < 0.001), and TpTe/QT ratio (P: 0.005) were significantly higher in patients with myocarditis. A comparison of receiver operating characteristic (ROC) curves was conducted using the Hanley and McNeil method. The area under the curve (AUC) of the electrocardiographic characteristics QT (AUC: 0.736; 95% CI [0.600-0.846]), QTP (AUC: 0.680; 95% CI [0.540-0.799]), and TpTe (AUC: 0.771; 95% CI [0.638-873]) and TpTe/QTc (AUC: 0.774; 95% CI [0.641-0.876]) and TpTe/QT (AUC: 0.726; 95% CI [0.589-0.838]) in myocarditis were not significantly different from each other but all of them were different from 0.5. Conclusion: Baseline ECGs of patients with myocarditis were associated with repolarization abnormalities. These novel findings may be one of the reasons underlying arrhythmic events in patients with myocarditis. [ABSTRACT FROM AUTHOR]

T-wave alternans (TWA) is an indicator of cardiac instability and is associated with life-threatening ventricular arrhythmias. Detection of TWA in the adult has been widely investigated and is used routinely for cardiac risk assessment. Detection of TWA in the fetus, however, is much more difficult due to the low amplitude and variable configuration of the signal, the presence of strong interferences, and the brevity of fetal TWA episodes. In this paper, we present a statistical detector based on the generalized likelihood ratio test that is designed for detection of TWA in the fetus. The performance of the detector is evaluated by constructing receiver-operator characteristic curves, using simulated data and real data from subjects with macroscopic TWA. The detector is capable of detecting TWA episodes as brief as 20 beats. The detection performance is improved significantly by modeling the fetal T-wave as a low-rank, low bandwidth signal, and using maximum likelihood estimation to estimate the model parameters. This approach enables all of the data to be used to estimate the noise statistics, providing highly effective suppression of interference, including maternal interference. The method is suitable for routine use because it can be applied to raw, unprocessed recordings, allowing automated analysis of extended fetal magnetocardiography recordings. [ABSTRACT FROM PUBLISHER]

We report a case of transient ECG abnormalities (negative T waves in the inferior leads) associated with presyncope related to acute cannabis consumption; after a few hours the ECG returned normal. Although pathophysiological mechanisms are not clear, it might be hypothesize a mismatch between increased oxygen demand and decreased oxygen supply or a marked hyperactivation of the sympathetic nervous system. [ABSTRACT FROM AUTHOR]