A novel ECG-index for prediction of ventricular arrhythmias in patients after myocardial infarction

ECG as a risk stratification tool in patients with wearable cardioverter-defibrillator

BACKGROUND

The wearable cardioverter defibrillator (WCD) is increasingly used in patients at elevated risk for ventricular arrhythmias but not fulfilling the indications for an implantable cardioverter defibrillator (ICD). Currently, there is an insufficient risk prediction of fatal arrhythmias in patients at risk. In this study, we assessed the prognostic role of baseline electrocardiogram (ECG) in WCD patients.

METHODS

WCD patients from diverse clinical institutions in Germany (n = 227) were retrospectively enrolled and investigated for the incidences of death or ventricular arrhythmias during WCD wearing. In addition, the widely accepted ECG predictors of adverse outcome were analyzed in patients with arrhythmic events.

RESULTS

Life-threatening arrhythmias occurred in 22 (9.7 %) patients, mostly in subjects with ischemic heart disease (15 of 22). There was no difference in baseline left ventricular ejection fraction (LVEF) in subjects with and without arrhythmic events (31.3 ± 7.9 % vs. 32.6 ± 8.3 %; p = 0,24). Patients with arrhythmia exhibited significantly longer QRS duration (109.5 ± 23.1 ms vs. 100.6 ± 22.3 ms, p = 0,04), Tpeak-Tend (Tp-e) (103.1 ± 15.6 ms vs. 93.2 ± 19.2 ms, p = 0,01) and QTc (475.0 ± 60.0 ms vs. 429.6 ± 59.4 ms, p < 0,001) intervals. In contrast, no significant differences were found for incidences of fragmented QRS (27.3 % vs. 24 %, p = 0.79) and inverted/biphasic T-waves (16.6 % vs. 22.7 %, p = 0,55). In multivariate regression analysis both Tp-e (HR 1.03; 95 % CI 1.001-1.057; p = 0.02) and QTc (HR 1.02; 95 % CI 1.006-1.026; p < 0.001) were identified as independent predictors of ventricular arrhythmias. After WCD use, the prophylactic ICD was indicated in 76 patients (33 %) with uneventful clinical course but persistent LVEF ≤35 %. The ECG analysis in these subjects did not reveal any relevant changes in arrhythmogenesis markers.

CONCLUSIONS

ECG repolarization markers Tp-e and QTc are associated with malignant arrhythmias in WCD patients and may be used - in addition to other established risk markers - to identify appropriate patients for ICD implantation.

Electroacupuncture Ameliorates Acute Myocardial Ischemic Injury and Long QT Interval in Mice through the α1A-Adrenergic Receptor: Electrophysiological, Morphological, and Molecular Evidence

Acute myocardial ischemia (AMI) is a condition caused by a decrease in blood flow to the heart that can sometimes predispose to acquired long QT syndrome (LQTS), thereby resulting in sudden cardiac death. Recent evidence indicates that electroacupuncture (EA) can alleviate MI injury, but its specific mechanism remains unclear. This study was aimed at investigating the efficacy of EA, which utilizes α_1A-adrenergic receptors (α_1A-AR) in alleviating MI injury as well as the resulting LQTS. The AMI model was established by ligating the left anterior descending arteries (LAD) of both the wild-type and α_1A gene-knockout mice and treating them with EA for three consecutive days. A PowerLab 16 physiological recorder was used to collect the electrocardiogram (ECG) while the serum creatine kinase isoenzymes (CK-MB), lactate dehydrogenase (LDH), and norepinephrine (NE) levels in myocardial tissue were determined by using the enzyme-linked immunosorbent assay (ELISA) kit. Moreover, TTC staining was used to observe the myocardial ischemic area, while H&E and TUNEL staining determined the pathological morphology of the myocardium. Quantitative real-time PCR (qRT-PCR) was used to detect the α_1A mRNA, and Western blot was used to detect the specific proteins, such as α_1A, cleaved caspase-3, Gq, PLC, p-PKCα, and p-hERG. Our results showed that EA could effectively reduce elevated ST-segment, shorten the extended QT interval, and reduce the serum myocardial enzyme content and the degree of pathological injury in wild mice with MI. EA can also decrease the expression of α_1A-AR, PLC, p-PKCα, and NE content in myocardial tissues of wild mice, while those of p-hERG increased in ischemic myocardial tissue. These findings suggested that α_1A-AR is involved in the development of MI as well as LQTS. Additionally, EA treatment improves the cardiac function and ischemic long QT interval and plays an important role in reducing the hERG inhibition through the α_1A-AR-mediated Gq/PLC/PKCα pathway and myocardial apoptosis. Hence, it is suggested that α_1A-AR might become a potential target for EA in treating AMI treatment of myocardial ischemia injury and acquired long QT intervals caused by MI.

Index of cardiac-electrophysiological balance and the effects of thrombolytic therapy on the electrocardiogram of patients with pulmonary embolism

OBJECTIVE

Different parameters on electrocardiograms (ECG) have been investigated to predict arrhythmia and mortality in patients with acute pulmonary embolism (APE). The acute effect of thrombolytic therapy (TT) on these parameters has not been investigated yet.

METHODS

We examined the data of 83 patients who were evaluated as high-risk APE and discharged from the hospital after TT. First, the high-risk APE patients' ECGs were compared with healthy control subjects (n = 55). After their admission and 24 hours later, the ECGs of patients with APE were compared. Heart rate, P-wave morphology, QRS duration, QT distance, Tp-e, and the index of cardiac electrophysiological balance (iCEB) were analyzed.

RESULTS

Although P maximum was not different between the groups' ECGs, heart rate, QT, QTc (corrected QT) interval, Tp-e intervals, Tp-e/QT ratio, and P wave dispersion were significantly higher in the APE group ( P values < 0.031). iCEB or iCEBc (corrected iCEB) values were lower in APE group ( P < 0.001). After TT, we determined a decrease in heart rate, Tp-e interval, and Tp-e/QT ratio ( P < 0.001). Although we detected a decrease in the QT and QTc interval and QT dispersion (QTd), QTd had no statistical significance (respectively P -value 0.013, 0.029, and 0.096). The iCEB and iCEBc levels were lower after TT ( P -value was 0.035 and 0.044 respectively).

CONCLUSION

The QT, QTc, Tp-e interval, Tp-e/QTc ratio, iCEB, and iCEBc values significantly decreased after TT. It may be thought that effective TT causes partial improvement in ventricular repolarization in an early period.

Changes in left ventricular electromechanical relations during targeted hypothermia

Background

Targeted hypothermia, as used after cardiac arrest, increases electrical and mechanical systolic duration. Differences in duration of electrical and mechanical systole are correlated to ventricular arrhythmias. The electromechanical window (EMW) becomes negative when the electrical systole outlasts the mechanical systole. Prolonged electrical systole corresponds to prolonged QT interval, and is associated with increased dispersion of repolarization and mechanical dispersion. These three factors predispose for arrhythmias. The electromechanical relations during targeted hypothermia are unknown.

We wanted to explore the electromechanical relations during hypothermia at 33 °C. We hypothesized that targeted hypothermia would increase electrical and mechanical systolic duration without more profound EMW negativity, nor an increase in dispersion of repolarization and mechanical dispersion.

Methods

In a porcine model (n = 14), we registered electrocardiogram (ECG) and echocardiographic recordings during 38 °C and 33 °C, at spontaneous and atrial paced heart rate 100 beats/min. EMW was calculated by subtracting electrical systole; QT interval, from the corresponding mechanical systole; QRS onset to aortic valve closure. Dispersion of repolarization was measured as time from peak to end of the ECG T wave. Mechanical dispersion was calculated by strain echocardiography as standard deviation of time to peak strain.

Results

Electrical systole increased during hypothermia at spontaneous heart rate (p < 0.001) and heart rate 100 beats/min (p = 0.005). Mechanical systolic duration was prolonged and outlasted electrical systole independently of heart rate (p < 0.001). EMW changed from negative to positive value (− 20 ± 19 to 27 ± 34 ms, p = 0.001). The positivity was even more pronounced at heart rate 100 beats/min (− 25 ± 26 to 41 ± 18 ms, p < 0.001). Dispersion of repolarization decreased (p = 0.027 and p = 0.003), while mechanical dispersion did not differ (p = 0.078 and p = 0.297).

Conclusion

Targeted hypothermia increased electrical and mechanical systolic duration, the electromechanical window became positive, dispersion of repolarization was slightly reduced and mechanical dispersion was unchanged. These alterations may have clinical importance. Further clinical studies are required to clarify whether corresponding electromechanical alterations are accommodating in humans.

ECG markers of local but not global increase in dispersion of ventricular repolarization (simulation study)

BACKGROUND

An increase in local dispersion of repolarization (DOR) may contribute more to arrhythmogenesis as compared to changes of global DOR. The aim of this simulation study was to find ECG markers of local increase in DOR in conditions where global DOR remains normal.

METHODS

In the framework of van Oosterom and Oostendorp ECGSIM model, the local DOR was increased in 10 different ventricular locations by (1) action potential duration (APD) shortening/lengthening both on epi- and endocardium, (2) epicardial APD shortening, and (3) endocardial APD shortening. The simulation cases where the increase in local DOR was accompanied by increase in global DOR were excluded from consideration. T-wave parameters were analyzed in the simulated precordial and anatomically ordered limb leads.

RESULTS

The increase in local DOR resulted in increased lead-to‑lead differences in Tpeak and Tend instants in 28 out of 32 simulated scenarios, and in an increased dispersion of Tpeak-Tend interval throughout 12 standard leads in 8 out of 32 simulated scenarios. In all simulations, the global DOR measured as a difference between earliest and latest repolarization times and standard APD deviation was the same.

CONCLUSIONS

The local increase in DOR was expressed in increased lead-to‑lead differences in Tpeak and Tend instants between adjacent anatomically ordered standard leads (aVL, I, aVR(-), II, aVF, III, and V1-V6), even if global DOR, Tpeak-Tend interval and Tpeak-Tend dispersion were within a normal range.

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

Aim

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

Methods

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

Results

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

Conclusions

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

Effects of nicorandil infusion on ECG parameters in patients with unstable angina pectoris and percutaneous coronary intervention

Background

Percutaneous coronary intervention (PCI) is effective in treating patients with acute coronary syndrome (ACS) but is associated with some serious complications. Nicorandil is an anti‐anginal agent acting to improve microvascular circulation and to increase coronary blood flow. The objective of this article is to evaluate the effects of intracoronary injection followed with continuous intravenous injection of nicorandil on ECG parameters in patients with unstable angina pectoris (UA) undergoing PCI.

Methods

A single‐center, self‐controlled clinical trial was conducted at the Second Hospital of Tianjin Medical University between January 2019 and April 2019. Sixty‐three consecutive patients with UA who received coronary angiography and selective PCI were enrolled. ECG was recorded and analyzed before and 24 hr after nicorandil infusion.

Results

Patients were divided into three groups: control group (n = 23, aged 63.43 ± 12.55 years), short‐term, and prolonged use with nicorandil group (n = 20 and 20, aged 66.45 ± 8.06 years and 65.80 ± 9.49 years, respectively). Clinical characteristics and ECG parameters were similar before PCI among three groups (p > .05). In nicorandil treatment groups, intervals of QTd and Tp‐e in patients post‐PCI were significantly shorter than that in control and pre‐PCI (p < .05).

Conclusions

Nicorandil infusion reduces QTd and Tp‐e interval in patients with UA. Further studies will be needed to determine whether these electrophysiological changes are associated with a reduction of ventricular arrhythmias and improved outcomes.

Progressive increase of the Tpeak-Tend interval is associated with ischaemia-induced ventricular fibrillation in a porcine myocardial infarction model

Aims

Repolarization indices of ECG have been widely assessed as predictors of ventricular arrhythmias. However, little is known of the dynamic changes of these parameters during continuous monitoring in acute ischaemic episodes. The objective of the study was to evaluate repolarization-related predictors of ventricular fibrillation (VF) during progression of experimental myocardial infarction.

Methods and results

Myocardial infarction was induced in 27 pigs by 40-min balloon inflation in the left anterior descending coronary artery, and 12-lead ECG was continuously recorded. Rate-corrected durations of the total Tpeak-Tend intervals measured from the earliest T-wave peak to the latest T-wave end in any lead were determined at baseline and at minute 1, 2, 5, and then every 5th minute of occlusion. There were 7 early (1-3 min) and 10 delayed (15-30 min) VFs in 16 pigs. Baseline Tpeak-Tend did not differ between animals with and without VF. Tpeak-Tend interval rapidly increased immediately after balloon inflation and was greater in VF-susceptible animals at 2-15 min compared with the animals that never developed VF (P < 0.05). Tpeak-Tend was tested as a predictor of delayed VFs. Median Tpeak-Tend at 10th min of occlusion was higher in delayed VF group (n = 10) than in animals without VF (n = 11): 138 [IQR 121-148] ms vs. 111 [IQR 106-127] ms, P = 0.02. Tpeak-Tend  ≥123 ms (10th min) predicted delayed VF episodes with HR = 4.5 95% CI 1.1-17.8, P = 0.031.

Conclusion

Tpeak-Tend prolongation during ischaemia progression predicts VF in the experimental porcine myocardial infarction model and warrants further testing in clinical settings of acute coronary syndromes.

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

Aims

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

Methods and results

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

Conclusion

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

Index of cardiac electrophysiological balance and transmural dispersion of the repolarization index relationships with pericardial fat volume and coronary calcification

AIM

To assess the possible relationship between coronary atherosclerosis markers, pericardial fat volume (PFV) and coronary artery calcification, with ECG markers of index of the cardiac electrophysiological balance (iCEB) and transmural dispersion of the repolarization in patients with suspected coronary artery disease.

METHODOLOGY

One hundred patients who underwent 64-slice multidetector computed tomography angiography were found to be eligible and were enrolled in the study.

RESULTS

Patients with high iCEB levels tended to have a higher PFV values compared with patients with low iCEB levels (median [interquartile range]) (152 [29-206] vs 96 [14-177]; p = 0.03). No significant differences in coronary artery calcification values were observed between iCEB and transmural dispersion of the repolarization groups.

CONCLUSION

A higher PFV value was observed in patients with high iCEB. Larger prospective studies are required to confirm the results.

A correlative study of myocardial infarction scar characteristics by DE-MR and the Lown's classification of ventricular premature beats

OBJECTIVE

Correlation between myocardial infarction (MI) scar by cardiac magnetic resonance and the Lown's classification of ventricular premature beats (VPBs) is poorly understood. This study aims to investigate the correlation between the MI scar characteristics by delayed-enhancement magnetic resonance imaging (DE-MRI) and the Lown's classification of VPBs.

METHODS

Sixty-five patients, in the convalescence stage and consolidation phase of MI, were included in this retrospective study. All patient were divided into VPBs group (n = 39) and non-VPBs group (n = 26 patients) according to the clinical diagnostic criteria of Universal Definition of MI scar. VPBs patients were assigned to Lown's I-II group and Lown's III-IV subgroup in accordance with the Lown classification criteria. Cardiac function parameters and MI scar characteristics were detected by cardiac magnetic resonance (CMR) and DE-MRI, respectively.

RESULTS

Lown's classification was negatively correlated with left ventricular ejection fraction (LVEF), peak ejection rate (PER) and peak filling rate (PFR) (-0.724, -0.628, -0.559), and positively correlated with MI area, MI integral, MI segments number and left ventricular end systolic volume (LVESV) (0.673, 0.655, 0.586, and 0.514), respectively.CONCLUSIONSThe study indicated that MI area and MI integral were strongly associated with Lown's classification.

Electrocardiographic Markers of Sudden Cardiac Death (Including Left Ventricular Hypertrophy)

Although the electrocardiograph (ECG) was invented more than 100 years ago, it remains the most commonly used test in clinical medicine. It is easy to perform, relatively cheap, and results are readily available. Interpretation, however, needs expertise and knowledge. New data, phenomenon, and syndromes are continually discovered by the ECG. It is important to differentiate between normal and abnormal ECGs first and then try to correlate the findings with clinical pathologies. Furthermore, the ECG is an integral part of the screening model for a variety of conditions such as channelopathies, athletes, preoperative risk profile, and remains the cardiologist's best friend.

ECG Parameters for Malignant Ventricular Arrhythmias: A Comprehensive Review

Many studies showed electrocardiogram (ECG) parameters are useful for predicting fatal ventricular arrhythmias (VAs). However, the studies have several shortcomings. Firstly, all studies lack of effective way to present behavior of various ECG parameters prior to the occurrence of the VAs. Secondly, they also lack of discussion on how to consider the parameters as abnormal. Thirdly, the reports do not include approaches to increase the detection accuracy for the abnormal patterns. The purpose of this study is to address the aforementioned issues. It identifies ten ECG parameters from various sources and then presents a review based on the identified parameters. From the review, it has been found that the increased risk of VAs can be represented by presence and certain abnormal range of the parameters. The variation of parameters range could be influenced by either gender or age. This study also has discovered the facts that averaging, outliers elimination and morphology detection algorithms can contribute to the detection accuracy.

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

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

QRS duration and dispersion for predicting ventricular arrhythmias in early stage of acute myocardial infraction

OBJECTIVE

To determine the relationship between QRS duration and dispersion and the occurrence of ventricular arrhythmias in early stages of acute myocardial infarction (AMI).

DESIGN

A retrospective, longitudinal descriptive study was carried out.

SETTING

Hospital General Universitario "Camilo Cienfuegos", Sancti Spíritus, Cuba. Secondary health care.

PATIENTS OR PARTICIPANTS

A total of 209 patients diagnosed with ST-segment elevation AMI from January 2012 to June 2014.

MAIN VARIABLES OF INTEREST

The duration and dispersion of the QT interval, corrected QT interval, and QRS complex were measured in the first electrocardiogram performed at the hospital. The presence of ventricular tachycardia/fibrillation was assessed during follow-up (length of hospital stay).

RESULTS

Arrhythmias were found in 46 patients (22%); in 25 of them (15.9%), arrhythmias originated in ventricles, and were more common in those subjects with extensive anterior wall AMI, which was responsible for 81.8% of the ventricular fibrillations and more than half (57.1%) of the ventricular tachycardias. The widest QRS complexes (77.3±13.3 vs. 71.5±6.4ms; P=.029) and their greatest dispersion (24.1±16.2 vs. 16.5±4.8ms; P=.019) were found on those leads that explore the regions affected by ischemia. The highest values of all measurements were found in extensive anterior wall AMI, with significant differences: QRS 92.3±18.8ms, QRS dispersion 37.9±23.9ms, corrected QT 518.5±72.2ms, and corrected QT interval dispersion 94.9±26.8ms. Patients with higher QRS dispersion values were more likely to have ventricular arrhythmias, with cutoff points at 23.5ms and 24.5ms for tachycardia and ventricular fibrillation, respectively.

CONCLUSIONS

Increased QRS duration and dispersion implied a greater likelihood of ventricular arrhythmias in early stages of AMI than increased duration and dispersion of the corrected QT interval.

12-Lead electrocardiogram as a predictor of sudden cardiac death: from epidemiology to clinical practice

Sudden cardiac death (SCD) causes a high burden of premature deaths in the population affecting subjects of all ages. The identification of subjects at high risk for SCD is of great importance as the prevention of many of these events would be possible with the treatment of underlying cardiac diseases and the use of implantable cardioverter-defibrillators (ICD). However, the current selection of patients for ICD therapy is based solely on left ventricular ejection fraction, and thus a substantial portion of patients at high risk does not qualify for the therapy. Role of the standard electrocardiogram (ECG) in SCD risk stratification has been under active research during the last decade and multiple abnormalities of depolarization and repolarization on the ECG associated with an increased risk of SCD have been identified. In this review, we describe the basic pathophysiological principles behind these changes. We also review the current knowledge of the prognostic significance of ECG predictors of SCD in the general population, and in patients with coronary heart disease (CHD), heart failure, cardiomyopathies, and in inheritable arrhythmia syndromes. Also, insights into the novel digital ECG signal processing techniques are provided.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Ventricular electrical heterogeneity in experimental diabetes mellitus: effect of myocardial ischemia

Aims of the study were to compare the development of electrocardiographic responses of the ischemia-induced heterogeneities of activation and repolarization in the ventricular myocardium of normal and diabetic animals. Body surface ECGs and unipolar electrograms in 64 epicardial leads were recorded before and during 20 min after the ligation of the left anterior descending artery in diabetic (alloxan model, 4 weeks, n=8) and control (n=8) rabbits. Activation times (ATs), end of repolarization times (RTs) and repolarization durations (activation-recovery intervals, ARIs) were determined in ischemic and periischemic zones. In contrast to the controls, the diabetic rabbits demonstrated the significant prolongation of ATs and shortening of ARIs (P<0.05) during ischemia in the affected region resulting in the development and progressive increase of the ARI and RT gradients across the ischemic zone boundary. The alterations of global and local dispersions of the RTs in diabetics correlated with the T(peak)-T(end) interval changes in the limb leads ECGs. In the ischemic conditions, the diabetic animals differed from the controls by the activation delay, significant repolarization duration shortening, and the increase of local repolarization dispersion; the latter could be assessed by the T(peak)-T(end) interval measurements in the body surface ECGs.

Ventricular repolarization markers for predicting malignant arrhythmias in clinical practice

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

Assessment of electrocardiographic parameters in patients with electrocution injury

BACKGROUND

Electrocution injury (EI) is a major problem in developing countries. The aim of this study is to investigate the effect of EI on electrocardiographic (ECG) parameters.

METHODS

A total of 43 patients hospitalized with diagnosis of EI were prospectively enrolled. Admission ECGs were compared with follow-up ECGs obtained one month after the event.

RESULTS

Maximum P wave duration (Pmax), minimum P wave duration (Pmin), P wave dispersion (PWD), PR interval, QRS complex duration, corrected QT duration (QTc), QT dispersion (QTD), T peak to T end (Tp-e) interval were longer and Tp-e interval/QT and Tp-e interval/QTc ratios were higher on admission ECGs compared to follow-up ECGs. Frontal QRS-T angle and frequency of patients with fragmented QRS were also higher on admission ECGs.

CONCLUSION

Our study revealed that EI causes significant deterioration of admission ECG parameters. The clinical use of these parameters in prediction of arrhythmias after EI warrants further studies.

Evaluation of Tp-Te interval and Tp-Te/QTc ratio in patients with coronary artery ectasia

AIM

Coronary artery ectasia (CAE) is commonly defined as local or generalized dilatation of a coronary vessel up to 1.5 times the diameter of an adjacent vessel. Tp-Te interval and Tp-Te/QT ratio have emerged as novel electrocardiographic markers of increased dispersion of ventricular repolarization. The aim of this study was to evaluate ventricular repolarization by using Tp-Te interval and Tp-Te/QT ratio in patients with CAE.

MATERIALS AND METHODS

Patients' records were retrospectively analyzed. Electrocardiogram of 28 patients, who were diagnosed as CAE were obtained and scanned. T wave peak to end interval, QT and corrected QT intervals and some other ECG intervals were measured. Electrocardiograms of age and sex matched 22 control individuals were also analyzed for comparison. Patients with critical coronary stenosis, moderate or severe valve disease, left and/or right heart failure, left and/or right ventricle hypertrophy, atrial fibrillation, moderate or severely abnormal electrolytes, right or left bundle block or patients who got pacemaker or ICD implanted and who undergo hemodialyses were excluded.

RESULTS

Baseline characteristics and QT, QTc intervals were similar in both groups. Tp-Te (97.71 ± 8.7 vs 85.23 ± 7.1; p < 0.001) and Tp-Te/QT (0.22 ± 0.0 vs 0.20 ± 0.0; p < 0.001) were significantly worse in CAE group.

CONCLUSIONS

T wave peak to end interval is a measure of transmural dispersion of repolarization in the left ventricle and accepted as a surrogate for increased ventricular arrhythmogenesis risk. Tp-Te and Tp-Te/QT are relatively new markers which also indicate repolarization defects. Our results show that CAE patients significantly higher values of Tp-Te and Tp-Te/QT than controls. These measurements may indicate increased arrhythmogenesis risk for individuals with CAE.