Dispersion of QT interval in patients with and without susceptibility to ventricular tachyarrhythmias after previous myocardial infarction

Increased Dispersion of Ventricular Repolarization as an Arrhythmic Risk Marker in Drug-free Patients With Major Depressive Disorder: A Preliminary Comparative Study

OBJECTIVE

Drug-free patients with major depressive disorder (MDD) are understudied in terms of increased risk for arrhythmias. In this study, we compared changes in corrected QT interval (QTc), QTc dispersion (QTcd), Tpeak-Tend (Tp-e), Tp-e/QT ratio, corrected JT interval (JTc), and JTc dispersion (JTcd), which are considered to be among the risk factors for the emergence of ventricular arrhythmias in patients with MDD.

METHODS

The study involved 50 patients with MDD who had been free of psychotropic medications for at least 1 month and 52 age-matched and sex-matched healthy controls. Illness-related characteristics, including duration of illness and Beck Depression Inventory scores, were recorded. Electrocardiography recordings made under a standardized procedure were performed for all participants, and arrhythmia risk markers were calculated from the electrocardiograms.

RESULTS

The patient group had significantly higher QTcd, JTc, and JTcd values compared with the controls. Among electrocardiogram markers, only Tp-e/QTc was significantly and inversely correlated with the duration of illness, while none of the markers was associated with Beck Depression Inventory scores.

CONCLUSIONS

Alterations in electrocardiogram-derived markers of ventricular arrhythmia, which can be obtained easily and inexpensively, can be evaluated for the prediction and prevention of severe cardiac conditions in patients with MDD and considered in selecting the safest antidepressant options available.

Effect of reperfusion strategy on QT dispersion in patients with acute myocardial infarction: Impact on in-hospital arrhythmia

BACKGROUND

Myocardial ischemia and ST-elevation myocardial infarction (STEMI) increase QT dispersion (QTD) and corrected QT dispersion (QTcD), and are also associated with ventricular arrhythmia.

AIM

To evaluate the effects of reperfusion strategy [primary percutaneous coronary intervention (PPCI) or fibrinolytic therapy] on QTD and QTcD in STEMI patients and assess the impact of the chosen strategy on the occurrence of in-hospital arrhythmia.

METHODS

This prospective, observational, multicenter study included 240 patients admitted with STEMI who were treated with either PPCI (group I) or fibrinolytic therapy (group II). QTD and QTcD were measured on admission and 24 hr after reperfusion, and patients were observed to detect in-hospital arrhythmia.

RESULTS

There were significant reductions in QTD and QTcD from admission to 24 hr in both group I and group II patients. QTD and QTcD were found to be shorter in group I patients at 24 hr than those in group II (53 ± 19 msec vs 60 ± 18 msec, P = 0.005 and 60 ± 21 msec vs 69+22 msec, P = 0.003, respectively). The occurrence of in-hospital arrhythmia was significantly more frequent in group II than in group I (25 patients, 20.8% vs 8 patients, 6.7%, P = 0.001). Furthermore, QTD and QTcD were higher in patients with in-hospital arrhythmia than those without (P = 0.001 and P = 0.02, respectively).

CONCLUSION

In STEMI patients, PPCI and fibrinolytic therapy effectively reduced QTD and QTcD, with a higher observed reduction using PPCI. PPCI was associated with a lower incidence of in-hospital arrhythmia than fibrinolytic therapy. In addition, QTD and QTcD were shorter in patients not experiencing in-hospital arrhythmia than those with arrhythmia.

Prolongation of QTc interval due to increased parity and great grand multiparity

Women are more prone to cardiac arrhythmias. Increased exposure to sex hormones may alter the ventricular repolarisation of the heart as the parity number increases. In this study, we aim to investigate the effect of parity number to electrocardiographic parameters. A total of 205 adult women were included for the study. Nulliparous (NP), primiparous (PP), multiparous (MP), grand multiparous (GMP) and great grand multiparous (GGMP) women constituted the study population. Increased parity has positive correlation with QTc interval (p=.000, r = 0.303). GGMP has significantly higher QTc compared to NP, PP, MP and GMP (p=.001, p=.000, p=.004 and p=.007, respectively). GGMP and parity have explanatory power on QTc (p=.019 and p=.020, respectively). Parity and GGMP affect cardiac repolarisation and prolong the QTc interval most probably due to repeated exposure to sex hormones. This study showed that GGMP and parity are independent risk factors for QTc interval prolongation.Impact StatementWhat is already known on this subject? Increased exposure to sex hormones may alter the ventricular repolarisation of the heart as the parity number increases. Previous studies showed that increased parity (up to 7) deteriorates ventricular diastolic functions, prolongs QTc interval and these conditions cause cardiovascular diseases.What do the results of this study add? In this study, we added great grand multiparity (10 or more parity) (GGMP) group that have never been studied before. We found that GGMP has much more impact on QTc prolongation than fewer parity groups and this result shows us that GGMP deteriorates ventricular functions more.What are the implications of these findings for clinical practice and/or further research? These results show us that women should be discouraged from having more delivery. Also, women with a pregnancy history of five and more (grand multiparity) should be evaluated with an electrocardiography and a cardiology consultation should be performed before re-conception. In the future, larger prospective studies are needed on this subject. In addition, other electrocardiographic parameters (QRS-T angle and Tpe/QTc in electrocardiography, etc.) that related with diastolic functions should be evaluated for comparison of GGMP and non-GGMP populations in future studies.

Prevalence and Risk Factors of QTc Prolongation During Pregnancy

Background

Prolonged QT intervals have been observed in pregnant women, which predispose them to a higher risk of potentially lethal ventricular arrhythmias. This study was designed to evaluate the prevalence of QTc prolongation in Chinese hospitalized parturient women with single and twin pregnancies, and to explore potential risk factors associated with QTc prolongation.

Methods

This retrospective study included 1,218 patients from a large Chinese population between January 2014 and October 2020. Data from parturient women with single and twin pregnancies without pre-pregnancy cardiac diseases were collected. QTc was corrected by the Fridericia formula [QTc = QT/RR(1/3)], and QTc ≥ 460 ms for females was defined as prolonged QTc, QTc ≥ 500 ms was defined as severely prolonged QTc. The prevalence and common risk factors of QTc prolongation during pregnancy were analyzed in this cohort. Uni- and multivariable logistic regression analysis were performed to identify clinical parameters associated with QTc prolongation in this population.

Results

The prevalence of QTc prolongation was 48.19% among this population, 10.56% in single pregnancy, 89.44% in twin pregnancies. The prevalence of severely prolonged QTc was 23.48% among the total cohort, 0.49% in single pregnancy, and 46.47% in twin pregnancies. The mean QTc interval was significantly longer in twin pregnancies than in single pregnancy (498.65 ± 38.24 vs. 424.96 ± 27.67 ms, P < 0.001). Systolic blood pressure, diastolic blood pressure, total cholesterol, serum uric acid, gestational hypertension and twin pregnancies were associated with QTc prolongation in parturient women.

Conclusion

This is the first study to assess the prevalence and risk factors of QTc prolongation between single and twin pregnancies. QTc prolongation is more prevalent, and QTc intervals are significantly longer in twin pregnancies as compared to single pregnancy.

Discrimination of Patients with Varying Degrees of Coronary Artery Stenosis by ECG and PCG Signals Based on Entropy

Coronary heart disease (CHD) is the leading cause of cardiovascular death. This study aimed to propose an effective method for mining cardiac mechano-electric coupling information and to evaluate its ability to distinguish patients with varying degrees of coronary artery stenosis (VDCAS). Five minutes of electrocardiogram and phonocardiogram signals was collected synchronously from 191 VDCAS patients to construct heartbeat interval (RRI)-systolic time interval (STI), RRI-diastolic time interval (DTI), HR-corrected QT interval (QTcI)-STI, QTcI-DTI, Tpeak-Tend interval (TpeI)-STI, TpeI-DTI, Tpe/QT interval (Tpe/QTI)-STI, and Tpe/QTI-DTI series. Then, the cross sample entropy (XSampEn), cross fuzzy entropy (XFuzzyEn), joint distribution entropy (JDistEn), magnitude-squared coherence function, cross power spectral density, and mutual information were applied to evaluate the coupling of the series. Subsequently, support vector machine recursive feature elimination and XGBoost were utilized for feature selection and classification, respectively. Results showed that the joint analysis of XSampEn, XFuzzyEn, and JDistEn had the best ability to distinguish patients with VDCAS. The classification accuracy of severe CHD-mild-to-moderate CHD group, severe CHD-chest pain and normal coronary angiography (CPNCA) group, and mild-to-moderate CHD-CPNCA group were 0.8043, 0.7659, and 0.7500, respectively. The study indicates that the joint analysis of XSampEn, XFuzzyEn, and JDistEn can effectively capture the cardiac mechano-electric coupling information of patients with VDCAS, which can provide valuable information for clinicians to diagnose CHD.

Predictive factors of poor blood collecting flow during leukocyte apheresis for cellular therapy

Leukocyte apheresis is necessary in various cellular therapies. However, maintenance of a stable flow rate during leukocyte apheresis is often difficult, even in patients or donors without major problems. Despite this, predictive methods and evidence regarding the reality of the situation are limited. We conducted a retrospective analysis involving adult patients who required leukocyte apheresis for the treatment of neoplasms using WT1-pulsed dendritic cell vaccine. Monocytes were separated from apheresis products to obtain dendritic cells. All the patients were pre-evaluated based on laboratory and chest X-ray findings and subjected to an identical apheresis procedure. The occurrence of poor blood collecting flow during leukocyte apheresis was monitored, and the frequency, clinical information, and associated risk factors were analyzed. Among 160 cases, poor blood collecting flow was observed in 53 cases (33.1%) in a median time of 54 min (range, 2-127 min) post-initiation of leukocyte apheresis. Owing to difficulty in obtaining higher collecting flow, a longer procedure time was required, and in some cases, the scheduled apheresis cycles could not be completed. Consequently, the number of harvested monocytes was low. Multivariable analysis indicated that female patients have an increased risk of poor inlet flow rate. Furthermore, prolonged QT dispersion (QTD) calculated using Bazett's formula was found to be a risk factor. Although the patients did not present any major problems during leukocyte apheresis, poor blood collecting flow was observed in some cases. Sex and pre-evaluated QTD might be useful predictors for these cases; however, further prospective evaluation is necessary.

Correlation between apnea-hypopnea index and Tp-Te interval, Tp-Te/QT, and Tp-Te/QTc ratios in obstructive sleep apnea

Background

Obstructive sleep apnea (OSA) is a highly prevalent sleep disorder associated with important cardiovascular complications including ventricular arrhythmias. Tp‐Te interval, Tp‐Te/QT, and Tp‐Te/QTc ratios are repolarization indices representing ventricular arrhythmogenic potential. These parameters are associated with ventricular arrhythmias and sudden cardiac death. The aim of this study was to investigate the correlation between apnea–hypopnea index and Tp‐Te, Tp‐Te/QT, and Tp‐Te/QTc in OSA.

Methods

We screened a total of 280 patients who underwent overnight polysomnography (PSG) between the years 2012–2017 at our institution. Patients were assigned into four groups based on severity of apnea–hypopnea index: 70 with apnea–hypopnea index (AHI) <5 (control group), 71 with 5 ≤ AHI < 15, 63 with 15 ≤ AHI < 30, and 76 with AHI ≥ 30. Tp‐Te, Tp‐Te/QT, and Tp‐Te/QTc were measured.

Results

Compared to control group, repolarization parameters were significantly prolonged in other groups (Tp‐Te interval: 68.3 ± 6.8, 71.8 ± 6.3, 79.1 ± 5.5, and 85.1 ± 6.4 ms, p < .001; Tp‐Te/QT ratio: 167.5 ± 12.7, 181.7 ± 13.0, 202.2 ± 10.0 and 219.4 ± 13.5, p < .001; Tp‐Te/QTc ratio: 151.1 ± 16.6, 167.6 ± 16.6, 193.7 ± 14.4, and 225.5 ± 17.0, p < .001). There was a significant trend toward higher Tp‐Te, Tp‐Te/QT, and Tp‐Te/QTc across higher AHI categories. In a univariate regression analysis, body mass index, smoking status, Tp‐Te, and Tp‐Te/QTc were significantly associated with the severity of AHI in OSA. Tp‐Te (OR 1.629, 95% CI 1.393–1.906, p < .001), Tp‐Te/QTc (OR 1,333 95% CI 1.247–1.424, p < .001), and smoking status (OR 5.771, 95% CI 1.025–32.479, p = .047) were found to be significant independent predictors of severity of AHI in a multivariate analysis, after adjusting for other risk parameters.

Conclusions

Our study showed that Tp‐Te, Tp‐Te/QT, and Tp‐Te/QTc were prolonged in patients with OSA. There was significant correlation between apnea–hypopnea index and these parameters.

Myocardial Repolarization Parameters and Neutrophil-to-Lymphocyte Ratio are Associated with Cardiotoxicity in Carbon Monoxide Poisoning

The present study aims to examine the clinical values of complete blood count (CBC) bioindicators and corrected QT (QT_c), T_peak - T_end interval (T_p-e), T_{peak dispersion} (T_{p disp}), and T_p-e/QT ratio that are the parameters of myocardial repolarization (M-rep) for cardiotoxicity, which develops due to acute carbon monoxide (CO) intoxication in patients admitted to the emergency service. This retrospective, cross-sectional, observational, and single-center study was conducted between April and June 2019. Statistical analysis was performed using the SPSS 23.0 software. Data of 234 participants were analyzed. Of these, 54.9% (n = 129) were female. Neutrophil-to-lymphocyte ratio (NLR), QT_c, T_p-e values were significantly high in the CO intoxication group (p < 0.001, p < 0.001, and p < 0.001, respectively), whereas T_p-e/QT_c ratio was significantly lower in the CO intoxication group than that in the control group (p < 0.001). NLR, T_p-e, T_{p disp} values were significantly high in the myocardial injury (M-inj) group (p < 0.001, p = 0.003, and p = 0.018, respectively). Furthermore, T_p-e/QT_c ratio was significantly low in the M-inj group (p = 0.002). M-rep parameters and NLR are associated with CO intoxication and the development of M-inj. Moreover, these bioindicators and can provide clinicians an early indication of M-inj.

Investigation of the Value of T peak to T end and QTc Intervals as Electrocardiographic Arrhythmia Susceptibility Markers in Acute Ischemic Stroke

INTRODUCTION

Arrhythmias are one of the most common causes of mortality in patients with acute ischemic stroke (AIS). This study aimed to investigate the relationships of arrhythmia susceptibility markers (QT, QTc, Tpe, Tpe-D, Tpe/QT, and Tpe/QTc) with the localization and volume of the ischemic area, the National Institutes of Health Stroke Scale (NIHSS) scores, and troponin levels in AIS.

METHODS

Patients diagnosed with AIS in the emergency department in the period from 01 November 2016 to 31 March 2019 were retrospectively reviewed. Patients admitted to the emergency department with no pathological ECG findings were included. The measurements of QT, QTc, Tpe, Tpe-D, Tpe/QTc, and Tpe/QT were performed under a digital microscope. The NIHSS scores, troponin values, and the ischemic area volume based on the diffusion-weighted magnetic resonance imaging findings at the time of admission were found.

RESULTS

A total of 135 patients, comprising 70 AIS patients and 65 individuals as controls, were included in the study. The male/female ratio was 73/62 and the mean age was 68.51±10.80 years. All of the ECG parameters in the AIS group and the control group were statistically significantly different between the groups except Tpe-D (p=0.454) (For QT, QTc, Tpe, Tpe/QTc, and Tpe/QT; p=0.003, 0.022, <0.001, 0.001, 0.001; respectively). QT, QTc, Tpe, Tpe/QTc, and Tpe/QT values were not significantly different between the groups with a NIHSS score of ≤5 and >5 (p=0.480, 0.688, 0.663, 0.512, 0.333, respectively).

CONCLUSIONS

Arrhythmia susceptibility markers including QT, QTc, Tpe, the values of Tpe-D, Tpe/QT, and Tpe/QTc are different in AIS patients compared to the individuals in the control group; therefore, these parameters can be included among the other parameters of close cardiac monitoring.

QTc dispersion as a novel marker in identifying patients requiring an epicardial approach for ablation of scar mediated ventricular tachycardia

Introduction

Epicardial exit sites of ventricular tachycardia (VT) are frequently encountered during VT ablation requiring an epicardial ablation approach for successful elimination of VT. We sought to assess the utility of repolarization markers in identifying individuals requiring an epicardial ablation approach in addition to an endocardial approach.

Methods

32 patients who underwent successful ablation for scar mediated VT were included in the study. Fourteen patients who required a combined endocardial and epicardial VT ablation were defined as epicardial VT group (Epi) whereas 18 patients who were successfully ablated from the endocardium alone constituted the endocardial VT group (Endo). Repolarization markers during sinus rhythm were compared between the two groups.

Results

A higher QTc max and QTc dispersion were seen in the Epi group compared to Endo group (479 ± 34 vs 449 ± 20, p = 0.008 and 63 ± 13 vs 38 ± 8, p = 0.001, respectively). Ts-p and Ts-p/Tp-e were higher in the Epi group (166 ± 23 vs 143 ± 23, p = 0.008 and 1.55 ± 0.26 vs 1.3 ± 0.21, p < 0.005). On multivariate regression, QTc dispersion was an independent predictor of the need for an epicardial approach to ablation. A QTc dispersion more than 51.5 msec identified individuals requiring a combined epicardial and endocardial approach to ablation with a sensitivity of 92.9% and a specificity of 100%.

Conclusions

Patients requiring an epicardial ablation have a higher QTc dispersion. A value greater than 51.5 msec reliably differentiates between the two groups with high sensitivity and specificity.

Association of QT dispersion with mortality and arrhythmic events-A meta-analysis of observational studies

BACKGROUND

The risk stratification of coronary heart disease (CHD) and/or heart failure (HF) patients with easily measured electrocardiographic markers is of clinical importance. The aim of this meta-analysis is to indicate whether increased QT dispersion (QTd) is associated with fatal and nonfatal outcomes in patients with CHD and/or HF.

METHODS

We systematically searched MEDLINE and Cochrane databases without restrictions until August 15, 2018 using the keyword "QT dispersion". Studies including data on the association between QTd and all-cause mortality, sudden cardiac death (SCD) or arrhythmic events in patients with HF and/or CHD were classified as eligible.

RESULTS

In the analysis including patients with CHD and/or HF, we found that QTd did not differ significantly in patients with SCD compared to no SCD patients while QTd was significantly greater in the group of all-cause mortality patients and in patients who experienced a sustained ventricular arrhythmia. Subgroup analysis showed that in myocardial infarction studies, QTd was significantly higher in patients with an arrhythmic event compared to arrhythmic event-free patients while a nonsignificant difference was found in QTd in patients who died from any cause compared to survivors. Similarly, in HF patients, the QTd was significantly greater in patients with an arrhythmic event while a nonsignificant difference was found regarding all-cause mortality and SCD outcomes.

CONCLUSIONS

QTd has a prognostic role for stratifying myocardial infarction or HF patients who are at higher risk of arrhythmic events. However, no prognostic role was found regarding all-cause mortality or SCD in this patient population.

Tp-e interval and Tp-e/QT ratio and their association with left ventricular diastolic dysfunction in Fabry disease without left ventricular hypertrophy

INTRODUCTION

In the early stage of the Fabry disease, diastolic dysfunction can occur before left ventricular hypertrophy (LVH). Cardiovascular complications, most of which are seen as malignant arrhythmias and heart failure, are the leading causes of death in these patients. The aim of the present study was to assess repolarization parameters of Fabry patients in early stage (without LVH) and to show the relationship between these parameters and left ventricular diastolic dysfunction.

METHODS

This cross-sectional single center study was carried out with newly diagnosed 23 Fabry patients and 20 healthy individuals, between April 2016 and September 2019. Diagnosis of Fabry disease was based on a measurement of enzyme activity in leukocytes and was confirmed by genetic analysis. Basic, demographic and clinical features were reviewed. The risk of ventricular arrhythmia was evaluated by calculating the electrocardiographic, the Tp-e and QT interval, corrected QT (QTc), Tp-e/QT and Tp-e/QTc ratios. Left ventricular systolic and diastolic dysfunctions were evaluated using echocardiography.

RESULTS

Tp-e interval (86.9 ± 6.2 vs. 73.8 ± 6.3 ms; p < 0.001), Tp-e/QT ratio (0.23 ± 0.008 vs. 0.21 ± 0.01; p < 0.001) and Tp-e/QTc ratio (0.21 ± 0.007vs. 0.18 ± 0.017; p < 0.001) were significantly higher in Fabry patients than the control group. There was a significant positive correlation between Tp-e interval and E/e' ratio (r = 0.626, p = 0.003) and Tp-e/QTc ratio and E/e' ratio (r = 0.578, p = 0.008) in Fabry patients.

CONCLUSION

Our study showed that the Tp-e interval, Tp-e/QT ratio, and Tp-e/QTc ratio, which are evaluated electrocardiographically in patients with pre-hypertrophic Fabry patients, are prolonged compared to normal healthy individuals. The most significant finding was the positive correlation found between repolarization parameters and LV diastolic dysfunction. These results may be indicative of an early subclinical cardiac involvement in Fabry patients, considering the diastolic dysfunction severity.

Prognostic implications of QRS dispersion for major adverse cardiovascular events in asymptomatic women and men: the Multi-Ethnic Study of Atherosclerosis

BACKGROUND

QRS dispersion measured as the difference between maximal and minimal QRS duration in the standard 12-lead electrocardiogram has been shown to be associated with increased mortality in heart failure (HF) patients and increased arrhythmic events in patients with cardiomyopathy.

AIMS

This study sought to examine the prognostic association between baseline QRS dispersion and future cardiovascular events in individuals without known prior cardiovascular disease.

METHODS

The association of QRS dispersion with cardiovascular events was examined in 6510 MESA (Multi-Ethnic Study of Atherosclerosis) participants. Participants with bundle branch block were excluded. Study participants were divided into two groups based on the 95th percentile of QRS dispersion (QRS dispersion < 34 ms [group I] and QRS dispersion ≥ 34 ms [group II]). Cox proportional hazard models adjusting for demographic and clinical risk factors were used to examine the association of QRS dispersion with incident cardiovascular events (major adverse cardiovascular events [MACE]) and mortality. Analysis was repeated by forcing Framingham risk factors.

RESULTS

Mean age was 62 ± 10 years in group I and 63 ± 10 years in group II (P = 0.02). QRS dispersion ≥ 34 ms was associated significantly with MACE (HR 1.30; 95% CI 1.04-1.62) and mortality (HR 1.33; 95% CI 1.03-1.73) after adjustment for cardiovascular risk factors and potential cofounders. Similar results were seen for mortality after adjustment for Framingham risk factors.

CONCLUSION

QRS dispersion ≥ 34 ms predicts cardiovascular events and mortality.

Experimental verification of the value of the Tpeak -Tend interval in ventricular arrhythmia inducibility in an early repolarization syndrome model

INTRODUCTION

In patients with early repolarization patterns on ECG, many researchers have studied to find predictors of fatal arrhythmia. However, there are no satisfying clinical predictors. We evaluated the value of the T_peak -T_end interval on pseudo-ECG in canine myocardial wedge preparation models of early repolarization syndrome.

METHODS AND RESULTS

Transmural pseudo-ECG and endocardial/epicardial action potentials were recorded from coronary-perfused canine left ventricular wedge preparations (n = 34). The I_to agonist NS5806 (8-10 µM), the calcium channel blocker verapamil (3 µM) and acetylcholine (2-3 µM) were used to mimic the disease model. A ventricular arrhythmia induction test was performed. QT_peak , QT_end , T_peak -T_end , and T_peak -T_end /QT_end were measured at 15 to 20 minutes after the provocative agent infusion. Polymorphic ventricular tachycardias (pVT) developed in 23 of the 34 preparations (67%). The maximal values of T_peak -T_end and T_peak -T_end /QT_end were recorded just before pVT induction. At baseline, without the provocative agents, T_peak -T_end and T_peak -T_end /QT_end were not different between pVT-induced and pVT-noninduced preparations. The T_peak -T_end of the pVT-induced preparations was longer than that of non-induced preparations (58 ± 26.8 msec vs 33 ± 6.8 msec, P < .001). The T_peak -T_end /QT_end of pVT- induced preparations was larger than that of noninduced preparations (0.220 ± 0.1017 vs 0.128 ± 0.0312, P < .001). The transmural and epicardial dispersion of repolarization of pVT-induced preparations were larger than those of pVT-noninduced preparations. The transmural dispersion of repolarization showed a positive correlation with T_peak -T_end .

CONCLUSION

T_peak -T_end predicted malignant ventricular arrhythmias in early repolarization syndrome models. T_peak -T_end reflects the repolarization heterogeneity of ventricular myocardium.

Evaluation of myocardial dispersion of repolarization in patients with heart transplantation

Background/aim

The number of patients with heart transplantation has dramatically increased in the last decade. Considerable studies have suggested that the interval from the peak to the end of the electrocardiographic T wave (Tp-e) may correspond to the transmural dispersion of repolarization and increased Tp-e interval and Tp-e/QT ratio are associated with malignant ventricular arrhythmias. We analyzed the dispersion of myocardial repolarization using electrocardiographic Tp-e interval and Tp-e/QTc ratio in patients with heart transplantation.

Materials and methods

This observational study included 38 patients (12 female and 26 male) with heart transplantation and 38 well-matched controls. From electrocardiograms, Tp-e interval and Tp-e/QTc ratio were calculated and compared between the 2 groups.

Results

Noninvasive arrhythmia indicators including Tp-e interval (84.63 ± 14.17 ms vs 71.82 ± 7.47 ms, P < 0.001), Tp-e/QTc ratio (0.19 ± 0.04 vs 0.16 ± 0.02, P < 0.001) and QTc interval except QT interval were significantly higher in transplanted hearts compared to normal hearts.

Conclusion

Patients with heart transplantation have increased myocardial dispersion of repolarization.

Electrocardiographic measures of ventricular repolarization dispersion and arrhythmic outcomes among ST elevation myocardial infarction patients with pre-infarction angina undergoing primary percutaneous coronary intervention

BACKGROUND

Arrhythmias are considered one of the major causes of death in ST elevation myocardial infarction (STEMI), particularly in the early in-hospital phase. Pre-infarction angina (PIA) has been suggested to have a protective role.

OBJECTIVES

To study the difference in acute electrocardiographic findings between STEMI patients with and without PIA and to assess the in-hospital arrhythmias in both groups.

MATERIAL AND METHODS

We prospectively enrolled 238 consecutive patients with STEMI. Patients were divided into two groups: those with or without PIA. ECG data recorded and analyzed included ST-segment resolution (STR) at 90 min, corrected QT interval (QTc) and dispersion (QTD), T-peak-to-T-end interval (Tp-Te), and dispersion and Tp-Te/QT ratio. In-hospital ventricular arrhythmias encountered in both groups were recorded. Predictors of in-hospital arrhythmias were assessed among different clinical and electrocardiographic parameters.

RESULTS

Of the 238 patients included, 42 (17%) had PIA and 196 (83%) had no PIA. Patients with PIA had higher rates of STR (p < 0.0001), while patients with no PIA had higher values of QTc (p = 0.006), QTD (p = 0.001), Tp-Te interval (p = 0.001), Tp-Te dispersion (p < 0.0001), and Tp-Te/QT ratio (p = 0.01) compared to those with angina preceding their incident infarction (PIA). This was reflected into significantly higher rates of in-hospital arrhythmias among patients with no PIA (20% vs. 7%, p = 0.04). Furthermore, longer Tp-Te interval and higher Tp-Te/QT ratio independently predicted in-hospital ventricular arrhythmias.

CONCLUSION

Pre-infarction angina patients had better electrocardiographic measures of repolarization dispersion and encountered significantly less arrhythmic events compared to patients who did not experience PIA.

Ventricular Arrhythmias in Patients with Obstructive Sleep Apnea

Obstructive Sleep Apnea (OSA) is a prevalent condition thought to increase in the future. Being mostly undiagnosed, the most serious complications are cardiovascular diseases, among which are arrhythmias. Controversy remains as to whether OSA is a primary etiologic factor for ventricular arrhythmias, because of the high incidence of cardiovascular comorbidities in OSA patients. Howev-er, there is mostly a strong evidence of a relation between OSA and ventricular arrhythmias. A few mechanisms have been proposed to be responsible for this association and some electrocardiographic changes have also been demonstrated to be more frequent in OSA patients. Treatment of OSA with Continuous Positive Airway Pressure (CPAP) has the potential to reduce arrhythmias and confer a mortality benefit.

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.

Obstructive sleep apnea is associated with increased QT corrected interval dispersion: the effects of continuous positive airway pressure

Introduction

Severe obstructive sleep apnea is associated with increased QT corrected interval dispersion and continuous positive airway pressure is thought to improve this arrhythmogenic marker.

Objective

The aim of the study was to determine the decrease of ratio of cardiovascular risk in patients with obstructive sleep apnea.

Methods

The study included 65 patients with severe obstructive sleep apnea who had an apnea-hypopnea index score of >30. Each patient underwent 12-channel electrocardiogram monitoring and polysomnography. Patients with an apnea-hypopnea index score of <5 were used as the control group. The control group also underwent electrocardiogram monitoring and polysomnography testing. The QT corrected interval dispersion levels of both groups were calculated. Three months after continuous positive airway pressure treatment, electrocardiogram recordings were obtained from the 65 patients with severe obstructive sleep apnea again, and their QT corrected interval dispersion values were calculated.

Results

There were 44 male and 21 female patients with severe obstructive sleep apnea syndrome. The age, gender, body mass index, initial saturation, minimum saturation, average saturation, and desaturation index were determined in both groups. The QT corrected intervals of the obstructive sleep apnea patients (62.48 ± 16.29 ms) were significantly higher (p = 0.001) than those of the control group (29.72 ± 6.30 ms). There were statistically significant differences between the QT corrected values before and after the continuous positive airway pressure treatment, with pretreatment QT corrected intervals of 62.48 ± 16.29 ms and 3-month post-treatment values of 41.42 ± 16.96 ms (p = 0.001). There was a positive and significant correlation between QT corrected interval dispersion periods and the apnea-hypopnea index and hypopnea index in obstructive sleep apnea patients (p = 0.001; r = 0.71; p = 0.001; r = 0.679, respectively).

Conclusion

Continuous positive airway pressure treatment reduced the QT corrected interval dispersion in patients with severe obstructive sleep apnea. In addition, shortening the QT corrected interval dispersion periods in patients with severe obstructive sleep apnea may reduce their risk of arrhythmias and cardiovascular disease.

Electrocardiogram Changes of Donepezil Administration in Elderly Patients with Ischemic Heart Disease

Objective

Donepezil, a widely used cholinesterase inhibitor for treating Alzheimer's disease, has been reported to induce bradyarrhythmias and torsade de pointes. In this study, we aimed at determining electrocardiogram changes of donepezil administration in elderly patients with ischemic heart disease, who tend to suffer from cognitive disorders.

Methods

Sixty patients with ischemic heart disease and mild cognitive impairment were treated with donepezil (5 mg/day) and followed up for at least four weeks. A twenty-four-hour ambulatory electrocardiogram was performed for the analysis of heart rate variability. The ECG parameters including heart rate (HR), PR and RR intervals, QT interval, and QRS duration were recorded at the baseline and after donepezil administration.

Results

Donepezil administration resulted in significant reduction in mean HR and the lowest HR and prolongation of PR and RR intervals, whereas it had no significant effects on QRS duration and QT parameters including QT, corrected QT interval, QT dispersion, and T_peak-end interval. HRV analysis showed that donepezil administration significantly improved parasympathetic function, indicated by decreased low/high frequency (LF/HF) ratio and high frequency (HF) components and oscillation of RR intervals.

Conclusions

These data demonstrated that donepezil administration decreased HR, prolonged PR interval, and increased parasympathetic function without affecting QRS duration and QT intervals, suggesting that it can be used safely in elderly patients with ischemic heart disease.

Evaluation of the Tp-Te Interval, QTc and P-Wave Dispersion in Patients With Coronary Artery Ectasia

Background

Coronary artery ectasia (CAE) is defined as a diffuse dilatation of the diameter of the ectatic segment of the coronary artery, 1.5 times greater than that of the adjacent segment. The Tp-Te interval, P-wave and QTc dispersions are relatively new electrocardiographic markers associated with an increased risk of developing arrhythmias. Despite CAE increasing in prevalence in recent years, there is a sparsity of data available about its arrhythmogenic effect. The aim of the study was to evaluate QTc, P-wave dispersion and Tp-Te and Tp-Te/QT ratio in patients with CAE.

Methods

A retrospective comparative study was designed for consecutive age- and sex-matched patients. Twenty patients with isolated CAE (group 1) and 20 control subjects (group 2), with normal coronary arteries, were included. All patients presented with chest pain and coronary angiogram was indicated. Outcome measures included Tp-Te interval, Tp-Te/QT ratio, QTc dispersion and P-wave dispersion. Measurement of electrocardiogram (ECG) parameters was conducted using standardized digital online software. Descriptive and inferential statistics were performed.

Results

Mean Tp-Te (95.5 ± 9.01 ms) and Tp-Te/QT ratio (0.22 ± 0.02) were significantly prolonged in CAE group (Tp-Te: 84 ± 5.62 ms, P = 0.00009; Tp-Te/QT ratio: 0.20 ± 0.01, P = 0.00004). In addition, QTc (31.2 ± 3.71 ms) and P-wave dispersion (31.9 ± 5.46 ms) were significantly increased in comparison to the control group (QTc: 27.6 ± 2.82 ms, P = 0.00532 and 20 ± 3.77 ms, P = 0.00003 respectively). However, there was no difference in ventricular activation time (VAT) between groups.

Conclusions

CAE ECGs were found to be associated with increased Tp-Te, Tp-Te/QT ratio, QTc intervals and P-wave dispersions. This may suggest that CAE existence has a pro-arrhythmogenic nature.

Prognostic Value of a New Marker of Ventricular Repolarization in Cirrhotic Patients

Background

There is still debate about the relationship between changes in ventricular repolarization on the surface electrocardiogram and cirrhosis severity.

Objective

To study the relationship between variables related to ventricular repolarization and the clinical severity of the cirrhotic disease.

Methods

We selected 79 individuals with hepatic cirrhosis, classified according to the Child-Pugh-Turcotte criteria (Child A, B, and C). We measured the QT and corrected QT (QTc) intervals, and the interval between the peak and the end of the T wave (TpTe), and we identified their minimum, maximum, and mean values in the 12-lead electrocardiogram. We also calculated the dispersion of the QT (DQT) and QTc (DQTc) intervals.

Results

In 12 months of clinical follow-up, nine subjects underwent hepatic transplantation (Child A: 0 [0%]; Child B: 6 [23.1%]; Child C: 3 [18.8%]; p = 0.04) and 12 died (Child A: 3 [12.0%]; Child B: 4 [15.4%]; Child C: 5 [31.3%]; p = 0.002). No significant differences were observed between the cirrhotic groups related to the minimum, maximum, and mean values for the QT, QTc, TpTe, DQT, and DQTc intervals. A minimum TpTe interval ≤ 50 ms was a predictor for the composite endpoints of death or liver transplantation with a sensitivity of 90% and a specificity of 57% (p = 0.005). In the Cox multivariate analysis, the Child groups and a minimum TpTe of ≤ 50 ms were independent predictors of the composite endpoints.

Conclusion

The intervals QT, QTc, DQT, DQTc, and TpTe have similar distributions between different severity stages in cirrhotic disease. The TpTe interval proved to be a prognostic marker in subjects with cirrhosis, regardless of disease severity (NCT01433848).

Spinal cord stimulation reduces ventricular arrhythmias during acute ischemia by attenuation of regional myocardial excitability

Myocardial ischemia creates autonomic nervous system imbalance and can trigger cardiac arrhythmias. We hypothesized that neuromodulation by spinal cord stimulation (SCS) will attenuate local cardiac sympathoexcitation from ischemia-induced increases in afferent signaling, reduce ventricular arrhythmias, and improve myocardial function during acute ischemia. Yorkshire pigs (n = 20) were randomized to SCS (50 Hz at 200-μs duration, current 90% motor threshold) or sham operation (sham) for 30 min before ischemia. A four-pole SCS lead was placed percutaneously in the epidural space (T₁-T₄), and a 56-electrode mesh was placed over the heart for high-resolution electrophysiological recordings, including activation recovery intervals (ARIs), activation time, repolarization time, and dispersion of repolarization. Electrophysiological and hemodynamic measures were recorded at baseline, after SCS/sham, during acute ischemia (300-s coronary artery ligation), and throughout reperfusion. SCS 1) reduced sympathoexcitation-induced ARI and repolarization time shortening in the ischemic myocardium; 2) attenuated increases in the dispersion of repolarization; 3) reduced ventricular tachyarrythmias [nonsustained ventricular tachycardias: 24 events (3 sham animals) vs. 1 event (1 SCS animal), P < 0.001]; and 4) improved myocardial function (dP/dt from baseline to ischemia: 1,814 ± 213 to 1,596 ± 282 mmHg/s in sham vs. 1,422 ± 299 to 1,380 ± 299 mmHg/s in SCS, P < 0.01). There was no change in ventricular electrophysiology during baseline conditions without myocardial stress or in the nonischemic myocardium. In conclusion, in a porcine model of acute ventricular ischemia, SCS reduced regional myocardial sympathoexcitation, decreased ventricular arrhythmias, and improved myocardial function. SCS decreased sympathetic nerve activation locally in the ischemic myocardium with no effect observed in the normal myocardium, thus providing mechanistic insights into the antiarrhythmic and myocardial protective effects of SCS.NEW & NOTEWORTHY In a porcine model of ventricular ischemia, spinal cord stimulation decreased sympathetic nerve activation regionally in ischemic myocardium with no effect on normal myocardium, demonstrating that the antiarrhythmic effects of spinal cord stimulation are likely due to attenuation of local sympathoexcitation in the ischemic myocardium and not changes in global myocardial electrophysiology.

Psychotropic drugs and ventricular repolarisation: The effects on QT interval, T-peak to T-end interval and QT dispersion

OBJECTIVE

We aimed to investigate in a clinical setting, the effects of different classes of psychotropic drugs on cardiac electrophysiological measures linked with an increased risk of sudden cardiac death.

METHODS

We conducted a cross-sectional study in a population of 1059 psychiatric inpatients studying the effects of various psychotropic drugs on the T-peak to T-end (TpTe) interval, QT dispersion and QT interval.

RESULTS

Methadone use showed a strong association with TpTe prolongation (odds ratio (OR)=12.66 (95% confidence interval (CI), 3.9-41.1), p<0.001), an effect independent from action on QT interval. Mood stabilisers showed significant effects on ventricular repolarisation: lithium was associated with a TpTe prolongation (OR=2.12 (95% CI, 1.12-4), p=0.02), while valproic acid with a TpTe reduction (OR=0.6 (95% CI, 0.37-0.98), p=0.04). Among antipsychotics, clozapine increased TpTe (OR=9.5 (95% CI, 2.24-40.39), p=0.002) and piperazine phenothiazines increased QT dispersion (OR=2.73 (95% CI, 1.06-7.02), p=0.037).

CONCLUSIONS

Treatment with psychotropic drugs influences TpTe and QT dispersion. These parameters might be considered to better estimate the sudden cardiac death risk related to specific medications. Beyond antipsychotics and antidepressants, mood stabilisers determine significant effects on ventricular repolarisation.

Evaluation of inhomogeneities of repolarization in patients with psoriasis vulgaris

INTRODUCTION

The arrhythmia potential has not been investigated adequately in psoriatic patients. In this study, we assessed the ventricular repolarization dispersion, using the Tp-e interval and the Tp-e/QT ratio, and investigated the association with inflammation.

MATERIAL AND METHODS

Seventy-one psoriasis vulgaris patients and 70 age- and gender-matched healthy individuals were enrolled in the study. The severity of the disease was calculated using Psoriasis Area and Severity Index scoring. The QTd was defined as the difference between the maximum and minimum QT intervals. The Tp-e interval was defined as the interval from the peak of the T wave to the end of the T wave. The Tp-e interval was corrected for heart rate. The Tp-e/QT ratio was calculated using these measurements.

RESULTS

There were no significant differences between the groups with respect to basal clinical and laboratory characteristics (p > 0.05). The Tp-e interval, the corrected Tp-e interval (cTp-e) and the Tp-e/QT ratio were also significantly higher in psoriasis patients compared to the control group (78.5 ±8.0 ms vs. 71.4 ±7.6 ms, p < 0.001, 86.3 ±13.2 ms vs. 77.6 ±9.0 ms, p < 0.001 and 0.21 ±0.02 vs. 0.19 ±0.02, p < 0.001 respectively). A significant correlation was detected between the cTp-e time and the Tp-e/QT ratio and the PASI score in the group of psoriatic patients (r = 0.51, p < 0.001; r = 0.59, p < 0.001, respectively).

CONCLUSIONS

In our study, we detected a significant increase in the Tp-e interval and the Tp-e/QT ratio in patients with psoriasis vulgaris. The Tp-e interval and the Tp-e/QT ratio may be predictors for ventricular arrhythmias in patients with psoriasis vulgaris.

Impacts of Glycoprotein IIb/IIIa Inhibition on QT Dispersion After Successful Percutaneous Coronary Intervention

Coronary ischemia augments inhomogeneity in ventricular repolarization. Decrease in the QT dispersion (QTd) following restoration of coronary blood flow to the ischemic myocardium by successful percutaneous coronary intervention (PCI) is an expected outcome. The purpose of the study was to seek whether glycoprotein IIb/IIIa (GP IIb/IIIa) inhibition has additional beneficial effects on QT dispersion after angiographically successful PCI. The study involved 111 consecutive patients scheduled for elective coronary balloon angioplasty with or without stent implantation. Sixty patients (mean age 58 ±9) were randomized to receive standard therapy including preprocedural aspirin, ticlopidine, and IV heparin, and 51 patients (mean age 54 ±10) were randomized to receive additional IV tirofiban infusion before the lesion was crossed with the guidewire. Standard 12-lead simultaneous ECG recordings for the measurement of QTd and corrected QTd (QTcd) (calculated by using Bazett’s formula) were obtained before and immediately after the procedure, and at the 6th, and 24th hours. Blood samples for detection of postprocedural myocardial damage (CK-MB and cTn-I) were taken before and immediately after the procedure, at the 6th, 12th, and 24th hours. In total, 128 stenoses were treated with PCI. Seventy of these lesions were in the standard therapy group and 58 in the tirofiban group. QTd and QTcd were not statistically different between the 2 groups before and immediately after the procedure and at the 6th hours, but at the 24th hour QTd and QTcd were significantly longer in the standard therapy group (p=0.047 and p=0.001, respectively). Postprocedural troponin-I elevation (B=0.692, p=0.037), maximum inflation pressure (B=0.182, p=0.001), and previous myocardial infarction (MI) (B=0.885, p=0.004) were defined as the predictors of the final QT dispersion at the 24th hour. QT dispersion significantly decreased after successful percutaneous coronary intervention. GP IIb/IIIa inhibition therapy was not superior by means of recovery of increased QT dispersion during the early hours of the intervention, but it prevented minor myocardial necrosis and provided more long-lasting recovery in QT dispersion as compared with heparin therapy. This impact of GP IIb/IIIa receptor inhibition on QTd may be a possible mechanism by which these drugs reduce cardiovascular events after PCI.

Effect of Direct Stent Implantation on QTc Dispersion

The aim of this study was to evaluate whether direct stenting is superior to conventional stent implantation technique with respect to QTc dispersion in prospectively selected patients with simple lesion morphology and class II stable angina undergoing elective coronary stenting. One hundred thirty-four consecutive patients were divided into 2 groups based on the stenting technique used: the direct stenting without predilation group, group I (n=64), and the stenting with predilation group, group II (n=70). All patients had single-vessel disease. The primary end point of the study was the QTc dispersion at the 24th hour and at the first month after the procedure and the secondary end point of the study was the major clinical events (MCEs) rate in the hospital period and up to 1 month. Baseline maximum QTc, minimum QTc, and QTc dispersion were not different between the 2 groups. QTc dispersion decreased from 47 ±8 msec before stent implantation to 41 ±11 msec at 24 hours and 37 ±7 msec 1 month after angioplasty in group I (p<0.006 and p<0.01, respectively), whereas QTc dispersion decreased from 49 ±9 msec before stent implantation to 46 ±8 msec at 24 hours and 42 ±10 msec 1 month after angioplasty in group II (p<0.03 and p<0.01, respectively). Compared with group II, the decrease in QTc dispersion was significantly greater at the 24th hour and at the first month after the procedure in group I (p<0.003 and p<0.001, respectively). There was a decreased trend toward MCE rate in group I in relation to that of group II, but the statistical difference was not significant. Direct stenting is a feasible and safe technique. It is superior to conventional stenting technique in decreasing the QTc dispersion at the 24th hour and at the first month after the procedure, whereas it is equivalent to single-vessel conventional stent implantation technique with respect to MCEs rate in the short-term period.

QT Interval Variability Index and QT Interval Duration in Different Sleep Stages: Analysis of Polysomnographic Recordings in Nonapneic Male Patients

The aim of the study was to determine whether different sleep stages, especially REM sleep, affect QT interval duration and variability in male patients without obstructive sleep apnea (OSA). Polysomnographic recordings of 30 patients were analyzed. Beat-to-beat QT interval variability was calculated using QTV index (QTVI) formula. For QTc interval calculation, in addition to Bazett's formula, linear and parabolic heart rate correction formulas with two separate α values were used. QTVI and QTc values were calculated as means of 2 awake, 3 NREM, and 3 REM sleep episodes; the duration of each episode was 300 sec. Mean QTVI values were not statistically different between sleep stages. Therefore, elevated QTVI values found in patients with OSA cannot be interpreted as physiological sympathetic impact during REM sleep and should be considered as a risk factor for potentially life-threatening ventricular arrhythmias. The absence of difference of the mean QTc interval values between NREM and REM stages seems to confirm our conclusion that sympathetic surges during REM stage do not induce repolarization variability. In patients without notable structural and electrical remodeling of myocardium, physiological elevation in sympathetic activity during REM sleep remains subthreshold concerning clinically significant increase of myocardial electrical instability.

Heterogeneity of Ventricular Sympathetic Nervous Activity is Associated with Clinically Relevant Ventricular Arrhythmia in Postoperative Patients with Tetralogy of Fallot

This study aimed to clarify whether there is an association between ventricular sympathetic nervous activity (SNA) and clinically relevant ventricular arrhythmia (a run of ≥ 3 consecutive ventricular beats, RVA) in postoperative patients with tetralogy of Fallot (TOF). We performed a retrospective study in a national referral center of pediatric cardiology in Japan. Twenty-four postoperative TOF patients (13 males, median age 17 years) undergoing myocardial (123)I metaiodobenzylguanidine (MIBG) scintigraphy were included. We measured the heart-to-mediastinum ratio (HMR) and washout ratio (WR) from planar MIBG myocardial scintigraphy. Tomographic images and polar maps were generated with 20 segments. The standard deviation of percentage uptake of 20 segments (SD-uptake) as an index of heterogeneous MIBG uptake to the ventricular myocardium was calculated. We compared these MIBG-derived variables with the patients' clinical profiles, including ECG findings and hemodynamics. Eight of 24 patients had RVA (RVA group), and the other 16 did not have RVA (non-RVA group). There were no significant differences in the HMR (1.9 ± 0.5 vs. 2.2 ± 0.4) and WR (50 ± 5 vs. 42 ± 10) between the two groups. SD-uptake was significantly higher in the RVA group than in the non-RVA group (15 ± 3 vs. 12 ± 3, p = 0.03). QT dispersion (ms) was also higher in the RVA group than in the non-RVA group (53 ± 23 vs. 44 ± 18, p = 0.04). Multivariate logistic regression showed that SD-uptake and QT dispersion were independent predictors in the RVA group (p = 0.02, p = 0.03). In addition to greater QT dispersion, heterogeneous SNA is associated with RVA in TOF patients postoperatively.

Contribution of Electrocardiogram in the Differentiation of Cardiac Amyloidosis and Nonobstructive Hypertrophic Cardiomyopathy

Due to similar manifestations of hypertensive ventricular walls and abnormal ventricular compliance, it is difficult to differentiate cardiac amyloidosis (CA) and nonobstructive hypertrophic cardiomyopathy (NOHCM) clinically. The purpose of the study was to investigate the value of electrocardiography (ECG) in the differentiation of the two diseases.

METHODS

We enrolled 46 consecutive patients with CA and 64 patients with NOHCM and compared their ECG characteristics.Compared with NOHCM patients, the ECG of CA patients showed more low voltage on limb leads (50% versus 1.6%), atrioventricular block (21.7% versus 4.7%), pseudo-infarct pattern (84.8% versus 39.1%), and longer QRS duration (104 ± 25 versus 98 ± 14 ms) (all P < 0.05). The QRS complex voltage of avR demonstrated the highest diagnostic performance (sensitivity 89%, specificity 94%, cut-off value 0.45mV) as assessed by ROC analysis. The combination of the R wave voltage of I and avR reached a sensitivity of 95% and a specificity of 87% for the diagnosis of amyloidosis.Compared with NOHCM patients, CA patients showed more ECG characteristics of low voltage on limb leads, pseudo-infarct pattern, atrioventricular block, and longer QRS duration. The combination of the R wave voltage of I, avR, and QRS was of diagnostic value in the differentiation of CA from NOHCM.

Exercise-Induced Repolarization Changes in Patients with Isolated Myocardial Bridging

BACKGROUND

Although myocardial bridging (MB) is defined as an angiographic phenomenon with a benign course, it has also been associated with adverse cardiovascular events. The effects of exercise on myocardial repolarization in patients with MB were tested in this study, with Tp-e and Tp-e/QT repolarization indexes.

MATERIAL AND METHODS

A total of 50 patients in whom isolated MB was diagnosed at coronary angiography (CAG) (Group I) and 48 patients with normal CAG results (Group II) were included in this study. The participants underwent treadmill exercise stress testing according to the Bruce protocol. QT dispersion (QTd) was defined as the minimum QT interval subtracted from the maximum. The Tp-e interval was defined as the difference between the QT and the QT peak time period. QTd and Tp-e intervals were calculated for all patients before and after exercise testing and differences between groups were compared.

RESULTS

At peak exercise, QTd and cQTd showed a significant increase in comparison to baseline values in the group of patients with myocardial bridges. Significant increases were also found with exercise in the Tp-e, cTp-e durations and Tp-e/QT ratio of the MB patient group in comparison to the baseline values. On the other hand, significant differences in QTd, cQTd, Tp-e, cTp-e intervals, and Tp-e/QT ratio during peak exercise in comparison with baseline values were not detected in the control group (p>0.05).

CONCLUSIONS

Significant increases in QTd, cQTd, Tp-e and cTp-e intervals and Tp-e/QT ratio were detected in the MB patients during exercise testing.

Spatial QT Dispersion Predicts Nonsustained Ventricular Tachycardia and Correlates with Confined Systodiastolic Dysfunction in Hypertrophic Cardiomyopathy

Objectives: An increased dispersion of myocardial repolarization represents one of the mechanisms underlying the arrhythmic risk in hypertrophic cardiomyopathy (HCM). We investigated spatial myocardial repolarization dispersion indices in HCM patients with nonsustained ventricular tachycardia (NSVT) and, contextually, their main clinical determinants. Methods: Fifty-two well-matched HCM outpatients were categorized into two groups according to the presence or the absence of NSVT at 24-hour Holter electrocardiogram (ECG) monitoring. Each patient underwent a clinical examination, including Doppler echocardiogram integrated with tissue Doppler imaging, cardiac magnetic resonance, and 12-lead surface ECG to calculate the dispersion for the following intervals: QRS, Q-Tend (QTe), Q-Tpeak, Tpeak-Tend (TpTe), J-Tpeak, and J-Tend. Results: The NSVT group showed only QTe dispersion and TpTe dispersion values to be significantly higher than their counterparts. NSVT occurrence was independently predicted by late gadolinium enhancement presence (p = 0.021) and QTe Bazett dispersion (p = 0.030), the latter strongly associated with the myocardial performance index (MPI) obtained at the basal segment of the interventricular septum (p = 0.0004). Conclusion: Our data support QTe dispersion as an easy and noninvasive tool for identifying HCM patients with NSVT propensity. The strong relationship between QTe dispersion and MPI allows us to hypothesize an intriguing link between electrical instability and confined myocardial areas of systodiastolic dysfunction.

P-wave and QT dispersion in patients with conversion disorder

OBJECTIVE

The aim of this study was to investigate QT dispersion (QTd), which is the noninvasive marker of ventricular arrhythmia and sudden cardiac death, and P-wave dispersion, which is the noninvasive marker of atrial arrhythmia, in patients with conversion disorder (CD).

PATIENTS AND METHODS

A total of 60 patients with no known organic disease who were admitted to outpatient emergency clinic and were diagnosed with CD after psychiatric consultation were included in this study along with 60 healthy control subjects. Beck Anxiety Inventory and Beck Depression Scale were administered to patients and 12-lead electrocardiogram measurements were obtained. Pd and QTd were calculated by a single blinded cardiologist.

RESULTS

There was no statistically significant difference in terms of age, sex, education level, socioeconomic status, weight, height, and body mass index between CD patients and controls. Beck Anxiety Inventory scores (25.2±10.8 and 3.8±3.2, respectively, P<0.001) and Beck Depression Scale scores (11.24±6.15 and 6.58±5.69, respectively, P<0.01) were significantly higher in CD patients. P-wave dispersion measurements did not show any significant differences between conversion patients and control group (46±5.7 vs 44±5.5, respectively, P=0.156). Regarding QTc and QTd, there was a statistically significant increase in all intervals in conversion patients (416±10 vs 398±12, P<0.001, and 47±4.8 vs 20±6.1, P<0.001, respectively).

CONCLUSION

A similar relation to that in literature between QTd and anxiety and somatoform disorders was also observed in CD patients. QTc and QTd were significantly increased compared to the control group in patients with CD. These results suggest a possibility of increased risk of ventricular arrhythmia resulting from QTd in CD patients. Larger samples are needed to evaluate the clinical course and prognosis in terms of arrhythmia risk in CD patients.

Reduction of QTD--A Novel Marker of Successful Reperfusion in NSTEMI. Pathophysiologic Insights by CMR

BACKGROUND/OBJECTIVES

Non-ST segment elevation myocardial infarction (MI) poses similar detrimental long-term prognosis as ST-segment elevation MI. No marker on ECG is established to predict successful reperfusion in NSTEMI. QT dispersion is increased by myocardial ischemia and reduced by successful restoration of epicardial blood flow by PCI. Whether QT dispersion reduction translates to smaller infarcts and thus indicates successful reperfusion is unknown. We hypothesized that the relative reduction of QT dispersion (QTD-Rrel ) on a standard ECG in acutely reperfused NSTEMI is related to infarct size and infarct transmurality as assessed by delayed enhancement CMR (DE-CMR).

METHODS AND RESULTS

69 patients with a first acute NSTEMI were included. QTD-Rrel was stratified according to LV function and volumes, infarct transmurality and size as assessed by DE-CMR. Extensive myocardial infarction was defined as above median infarct size. LV function and end-systolic volume were only mildly related to QTD-Rrel . QTD-Rrel was inversely related to infarct size (r=-0.506,p=0.001) and infarct transmurality (r=-0.415, p=0.001). QTD-Rrel was associated with extensive myocardial infarction in univariate analysis (odds ratio (OR) 0.958, CI 0.935-0.982; p=0.001). Compared to clinical and angiographic data QTD-Rrel remained the only independent predictor of non-transmural infarcts (OR 1.110, CI 1.055-1.167; p=0.049).

CONCLUSION

In patients with acute Non-ST-Segment Myocardial infarction QTd-Rrel calculated on a surface ECG prior and post PCI for restoration of epicardial blood flow detects small, non-transmural infarcts as assessed by delayed enhancement CMR. Thus, QTd-Rrel can indicate successful reperfusion therapy.

Sympathetic nerve stimulation, not circulating norepinephrine, modulates T-peak to T-end interval by increasing global dispersion of repolarization

BACKGROUND

T-peak to T-end interval (Tp-e) is an independent marker of sudden cardiac death. Modulation of Tp-e by sympathetic nerve activation and circulating norepinephrine is not well understood. The purpose of this study was to characterize endocardial and epicardial dispersion of repolarization (DOR) and its effects on Tp-e with sympathetic activation.

METHODS AND RESULTS

In Yorkshire pigs (n=13), a sternotomy was performed and the heart and bilateral stellate ganglia were exposed. A 56-electrode sock and 64-electrode basket catheter were placed around the epicardium and in the left ventricle (LV), respectively. Activation recovery interval, DOR, defined as variance in repolarization time, and Tp-e were assessed before and after left, right, and bilateral stellate ganglia stimulation and norepinephrine infusion. LV endocardial and epicardial activation recovery intervals significantly decreased, and LV endocardial and epicardial DOR increased during sympathetic nerve stimulation. There were no LV epicardial versus endocardial differences in activation recovery interval during sympathetic stimulation, and regional endocardial activation recovery interval patterns were similar to the epicardium. Tp-e prolonged during left (from 40.4±2.2 ms to 92.4±12.4 ms; P<0.01), right (from 47.7±2.6 ms to 80.7±11.5 ms; P<0.01), and bilateral (from 47.5±2.8 ms to 78.1±9.8 ms; P<0.01) stellate stimulation and strongly correlated with whole heart DOR during stimulation (P<0.001, R=0.86). Of note, norepinephrine infusion did not increase DOR or Tp-e.

CONCLUSIONS

Regional patterns of LV endocardial sympathetic innervation are similar to that of LV epicardium. Tp-e correlated with whole heart DOR during sympathetic nerve activation. Circulating norepinephrine did not affect DOR or Tp-e.

Repolarization Parameters Are Associated With Mortality In Chagas Disease Patients In The United States

Objective

The goal of this study was to examine the association between ECG repolarization parameters and mortality in Chagas disease (CD) patients living in the United States.

Methods

CD patients with cardiomyopathy (CM) and bundle branch block (BBB) or BBB alone were compared to age- and sex-matched controls. QT interval, QT dispersion (QTd), T wave peak to T wave end duration (Tp-Te) and T wave peak to T wave end dispersion ((Tp-Te)d) were measured. Presence of fractionated QRS (fQRS) was also assessed. The main outcome measure was the association between ECG parameters and mortality or need for cardiac transplant.

Results

A total of 18 CM and 13 BBB CD patients were studied with 97% originating from Mexico or Central America. QTd (60.0±15.0 ms vs 43.5±9.8 ms, P=0.0002), Tp-Te (102.6±29.3 ms vs 77.1±11.0 ms, P=0.0002) and (Tp-Te)d (39.5±9.4 ms vs 22.7±7.6 ms, P<0.0001) were prolonged in CD CM patients compared to CM controls. Chagas CM patients had more fQRS then controls (84.2±0.10% vs 33.3±0.11%, p=0.0005). QTd (59.9±15.0 ms vs 29.5±6.9 ms, P=0.0001) and (Tp-Te)d (40.0±15.9 ms vs 18.5±5.4 ms, p<0.0001) were longer in the CD BBB group compared to BBB controls. Univariate analysis showed QTd (56.9±15.0 ms vs 46.5±17.3 ms, p=0.0412) and (Tp-Te)d (36.8±13.5 ms vs 28.5±13.3 ms, p=0.0395) were associated with death and/or need for cardiac transplant.

Conclusion

Our results indicate that P-max and PD are useful electrocardiographic markers for identifying the β-TM-high-risk patients for AF onset, even when the cardiac function is conserved.

Heart rate variability parameters and ventricular arrhythmia correlate with pulmonary arterial pressure in adult patients with idiopathic pulmonary arterial hypertension

OBJECTIVE

This aim of this study was to correlate heart rate variability (HRV) parameters to pulmonary arterial pressure (PAP) in patients with purely idiopathic pulmonary arterial hypertension (IPAH).

BACKGROUND

HRV is decreased in patients with PAH. Whether HRV indices can be used to assess PAP in IPAH patients remains unclear.

METHODS

HRV parameters obtained by 24-h ECG were evaluated in 26 IPAH patients and 51 controls.

RESULTS

Time-domain HRV parameters (SDNN, p < 0.0001; SDANN, p < 0.0001; RMSSD, p = 0.006) were lower in IPAH patients. Frequency-domain indices (high-frequency power, HFP, p = 0.001; low-frequency power, LFP, p = 0.003; total power, TP, p = 0.001) were also decreased in IPAH patients. In IPAH patients, RMSSD (p = 0.001), HFP (p = 0.015), and LFP (p = 0.027) were significantly correlated with PAP. IPAH patients had longer QTc intervals (p < 0.0001) and more premature ventricular contractions (p < 0.0001) than controls.

CONCLUSIONS

IPAH is associated with autonomic dysfunction. RMSSD, HFP, and LFP may be used as a supplemental tool to assess PAP in IPAH patients. IPAH patients with autonomic dysfunction are at high risk for ventricular arrhythmia.

Short-term effect of percutaneous recanalization of chronic total occlusions on QT dispersion and heart rate variability parameters

Background

QT dispersion (QTd), which is a measure of inhomogeneity of myocardial repolarization, increases following impaired myocardial perfusion. Its prolongation may provide a suitable substrate for life-threatening ventricular arrhythmias. We investigated the changes in QTd and heart rate variability (HRV) parameters after successful coronary artery revascularization in a patient with chronic total occlusions (CTO).

Material/Methods

This study included 139 successfully revascularized CTO patients (118 men, 21 women, mean age 58.3±9.6 years). QTd was measured from a 12-lead electrocardiogram and was defined as the difference between maximum and minimum QT interval. HRV analyses of all subjects were obtained. Frequency domain (LF: HF) and time domain (SDNN, pNN50, and rMSSD) parameters were analyzed. QT intervals were also corrected for heart rate using Bazett’s formula, and the corrected QT interval dispersion (QTcd) was then calculated. All measurements were made before and after percutaneous coronary intervention (PCI).

Results

Both QTd and QTcd showed significant improvement following successful revascularization of CTO (55.83±14.79 to 38.87±11.69; p<0.001 and 61.02±16.28 to 42.92±13.41; p<0.001). The revascularization of LAD (n=38), Cx (n=28) and RCA (n=73) resulted in decrease in HRV indices, including SDDN, rMSSD, and pNN50, but none of the variables reached statistical significance.

Conclusions

Successful revascularization of CTO may result in improvement in regional heterogeneity of myocardial repolarization, evidenced as decreased QTcd after the PCI. The revascularization in CTO lesions does not seem to have a significant impact on HRV.

Diagnostic value of magnetocardiography in coronary artery disease and cardiac arrhythmias: a review of clinical data

Despite the availability of several advanced non-invasive diagnostic tests such as echocardiography and magnetic resonance imaging, electrocardiography (ECG) remains as the most widely used diagnostic technique in clinical cardiology. ECG detects electrical potentials that are generated by cardiac electrical activity. In addition to electrical potentials, the same electrical activity of the heart also induces magnetic fields. These extremely weak cardiac magnetic signals are detected by a non-invasive, contactless technique called magnetocardiography (MCG), which has been evaluated in a number of clinical studies for its usefulness in diagnosing heart diseases. We reviewed the basic principles, history and clinical data on the diagnostic role of MCG in coronary artery disease and cardiac arrhythmias.

Electrocardiographic predictors of sudden cardiac death in patients with left ventricular hypertrophy

BACKGROUND

Left ventricular hypertrophy (LVH) has been associated with increased risk of sudden cardiac death (SCD), and improvements in risk stratification methodology are warranted.

METHODS

We evaluated electrocardiographic intervals as potential markers of SCD risk in LVH. Corrected QT, QRS, and JT intervals were evaluated in consecutive cases with SCD and LVH from the ongoing Oregon Sudden Unexpected Death study who underwent a 12-lead electrocardiogram (EKG) and echocardiogram prior to and unrelated to the SCD event. Comparisons of age, gender, body mass index, LV ejection fraction, and EKG intervals together with clinical conditions (hypertension and diabetes) were conducted with geographically matched controls that had coronary artery disease but no history of ventricular arrhythmias or cardiac arrest. LVH was determined using the modified American Society of Echocardiography equation for LV mass. Independent samples t-test, Pearson's chi-square test, and multiple logistic regression were used for statistical comparisons.

RESULTS

Of the 109 cases and 49 controls who met study criteria, age, gender, and comorbidities were similar among cases and controls. The mean LV mass index was not significantly different in cases compared to controls. However mean QTc (470.6 ± 53.6 ms vs 440.7 ± 38.7 ms; P < 0.0001) and QRS duration (113.6 ± 30.0 ms vs 104.9 ± 18.7 ms; P = 0.03) were significantly higher in cases than controls. In logistic regression analysis, prolonged QTc was the only EKG interval significantly associated with SCD (OR 1.72 [1.23-2.40]).

CONCLUSION

Prolonged QTc was independently associated with SCD among subjects with LVH and merits further evaluation as a predictor of SCD in LVH.

Beat-to-beat vectorcardiographic analysis of ventricular depolarization and repolarization in myocardial infarction

Objectives

Increased beat-to-beat variability in the QT interval has been associated with heart disease and mortality. The purpose of this study was to investigate the beat-to-beat spatial and temporal variations of ventricular depolarization and repolarization in vectorcardiogram (VCG) for characterising myocardial infarction (MI) patients.

Methods

Standard 12-lead ECGs of 84 MI patients (22 f, 63±12 yrs; 62 m, 56±10 yrs) and 69 healthy subjects (17 f, 42±18 yrs; 52 m, 40±13 yrs) were investigated. To extract the beat-to-beat QT intervals, a template-matching algorithm and the singular value decomposition method have been applied to synthesise the ECG data to VCG. Spatial and temporal variations in the QRS complex and T-wave loops were studied by investigating several descriptors (point-to-point distance variability, mean loop length, T-wave morphology dispersion, percentage of loop area, total cosine R-to-T).

Results

Point-to-point distance variability of QRS and T-loops (0.13±0.04 vs. 0.10±0.04, p< 0.0001 and 0.16±0.07 vs. 0.13±0.06, p< 0.05) were significantly larger in the MI group than in the control group. The average T-wave morphology dispersion was significantly higher in the MI group than in the control group (62°±8° vs. 38°±16°, p< 0.0001). Further, its beat-to-beat variability appeared significantly lower in the MI group than in the control group (12°±5° vs. 15°±6°, p< 0.005). Moreover, the average percentage of the T-loop area was found significantly lower in the MI group than the controls (46±17 vs. 55±15, p< 0.001). Finally, the average and beat-to-beat variability of total cosine R-to-T were not found statistically significant between both groups.

Conclusions

Beat-to-beat assessment of VCG parameters may have diagnostic attributes that might help in identifying MI patients.