Risk stratification for sudden cardiac death in dilated cardiomyopathy using microvolt-level T-wave alternans

A novel risk model for predicting potentially life-threatening arrhythmias in non-ischemic dilated cardiomyopathy (DCM-SVA risk)

BACKGROUND

Non-ischemic dilated cardiomyopathy (DCM) can be complicated by sustained ventricular arrhythmias (SVA) and sudden cardiac death (SCD). By now, left-ventricular ejection fraction (LV-EF) is the main guideline criterion for primary prophylactic ICD implantation, potentially leading either to overtreatment or failed detection of patients at risk without severely impaired LV-EF. The aim of the European multi-center study DETECTIN-HF was to establish a clinical risk calculator for individualized risk stratification of DCM patients.

METHODS

1393 patients (68% male, mean age 50.7 ± 14.3y) from four European countries were included. The outcome was occurrence of first potentially life-threatening ventricular arrhythmia. The model was developed using Cox proportional hazards, and internally validated using cross validation. The model included seven independent and easily accessible clinical parameters sex, history of non-sustained ventricular tachycardia, history of syncope, family history of cardiomyopathy, QRS duration, LV-EF, and history of atrial fibrillation. The model was also expanded to account for presence of LGE as the eight8h parameter for cases with available cMRI and scar information.

RESULTS

During a mean follow-up period of 57.0 months, 193 (13.8%) patients experienced an arrhythmic event. The calibration slope of the developed model was 00.97 (95% CI 0.90-1.03) and the C-index was 0.72 (95% CI 0.71-0.73). Compared to current guidelines, the model was able to protect the same number of patients (5-year risk ≥8.5%) with 15% fewer ICD implantations.

CONCLUSIONS

This DCM-SVA risk model could improve decision making in primary prevention of SCD in non-ischemic DCM using easily accessible clinical information and will likely reduce overtreatment.

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.

Ability of microvolt T-wave alternans to modify risk assessment of ventricular tachyarrhythmic events: a meta-analysis

BACKGROUND

Prior studies have indicated that the magnitude of risk association of microvolt T-wave alternans (MTWA) testing appears to vary with the population studied. We performed a meta-analysis to determine the ability of MTWA to modify risk assessment of ventricular tachyarrhythmic events (VTEs) and sudden cardiac death (SCD) across a series of patient risk profiles using likelihood ratio (LR) testing, a measure of test performance independent of disease prevalence.

METHODS

We identified original research articles published from January 1990 to January 2011 that investigate spectrally derived MTWA. Ventricular tachyarrhythmic event was defined as the total and arrhythmic mortality and nonfatal sustained or implantable cardioverter-defibrillator-treated ventricular tachyarrhythmias. Summary estimates were created for positive and nonnegative MTWA results using a random-effects model and were expressed as positive (LR+) and negative (LR-) LRs.

RESULTS

Of 1,534 articles, 20 prospective cohort studies met our inclusion criteria, consisting of 5,945 subjects predominantly with prior myocardial infarction or left ventricular dysfunction. Although there was a modest association between positive MTWA and VTE (relative risk 2.45, 1.58-3.79) and nonnegative MTWA and VTE (3.68, 2.23-6.07), test performance was poor (positive MTWA: LR+ 1.78, LR- 0.43; nonnegative MTWA: LR+ 1.38, LR- 0.56). Subgroup analyses of subjects classified as prior VTE, post-myocardial infarction, SCD-HeFT type, and MADIT-II type had a similar poor test performance. A negative MTWA result would decrease the annualized risk of VTE from 8.85% to 6.37% in MADIT-II-type patients and from 5.91% to 2.60% in SCD-HeFT-type patients.

CONCLUSIONS

Despite a modest association, results of spectrally derived MTWA testing do not sufficiently modify the risk of VTE to change clinical decisions.

Predictive value of microvolt T-wave alternans for cardiac death or ventricular tachyarrhythmic events in ischemic and nonischemic cardiomyopathy patients: a meta-analysis

BACKGROUND

Microvolt T-wave alternans (MTWA) has been proposed as a predictor of the risk of ventricular tachyarrhythmias (VT) and sudden cardiac death (SCD). Aim of this study was to perform a systematic review of the literature and a meta-analysis of MTWA in primary prevention patients with ischemic and nonischemic cardiomyopathy.

METHODS

The positive predictive value (PPV), negative predictive value (NPV), and relative risk (RR) of MTWA in predicting death, cardiac death, and SCD during follow-up were reported.

RESULTS

Fifteen studies involving 5681 patients (mean age 62 years, mean ejection fraction 32%) were included. The summary PPV during the average 26-month follow-up was 14% (95% CI: 13-15); NPV was 95% (95% CI: 94-96), and the univariate RR was 2.35 (95% CI: 1.68-3.28). The predictive value of MTWA was similar in patients with ischemic and nonischemic cardiomyopathy. The average RR for SCD or VT events of an abnormal MTWA was 2.40, similar to that for cardiac death. When we grouped the studies together depending upon whether beta-blockers were withheld prior to MTWA screening, the beta-blockers group showed an RR of 5.88. By contrast, the group in which beta-blocker therapy was withheld had an RR of 1.63.

CONCLUSION

A positive MTWA determined an approximately 2.5-fold higher risk of cardiac death and life-threatening arrhythmia and showed a very high NPV both in ischemic and nonischemic patients. An abnormal MTWA test was associated with a 5-fold increased risk for cardiac mortality in the low-indeterminate group and about a 6-fold increased risk in beta-blockers group.

T-wave alternans and sudden cardiac death

Sudden cardiac death (SCD) is the leading cause of mortality in patients with ischemic heart disease and left ventricular dysfunction. The majority of SCD are due to ventricular tachyarrhythmias. SCD strikes many asymptomatic patients and often is the first manifestation of heart disease. Thus, reliable determination of arrhythmic risk is warranted to guide preventive therapy. To highlight the prognostic value of microvolt-level electrical alternans of the T-wave (MTWA) in patients at risk for SCD, most of the pertinent published articles in the Medline, Scopus, and EBSCO Host research databases have been reviewed. MTWA has been proposed to be a strong and independent predictor of all-cause and arrhythmic mortality. The high predictive value of MTWA in patient with cardiomyopathy varies significantly depending on the population studied. Combining with other indices or having serial MTWA readings could overcome MTWA limitations. Redefining MTWA readings may expand its prognostic utility.

Combined prognostic value of peak O(2) uptake and microvolt level T-wave alternans in patients with idiopathic dilated cardiomyopathy

BACKGROUND

Despite the great improvement in clinical management of patients with idiopathic dilated cardiomyopathy (DCM), sudden cardiac death (SCD) and death due to worsening heart failure (HF) remain a challenging problem. The assessment of oxygen consumption (peakVO(2)) has been recognized as an independent marker of mortality. Nevertheless peakVO(2) is not helpful in the risk stratification of SCD. Given this limitation, the association with another non-invasive test able to predict SCD such as microvolt level T-wave alternans (MTWA) would be useful.

OBJECTIVES

To determine the combined predictive value of peakVO(2) and MTWA in patients with DCM.

METHODS

Seventy consecutive DCM patients were prospectively investigated. PeakVO(2) and MTWA were determined during bicycle exercise testing. Primary composite study end-point was defined as major cardiac events (MCE): total cardiac death or documented sustained VT/VF (including appropriate ICD shock). Secondary end-point was defined as arrhythmic events (AE): SCD or documented sustained VT/VF.

RESULTS

Thirty-nine patients (55%) had a peakVO(2)<10 ml/kg/min, while 40 patients (57%) showed an abnormal MTWA test. During an average follow-up of 19.2+/-10.7 months, 11 MCE of which 6 AE have been documented. Among patients with abnormal MTWA and peakVO(2)<10 ml/kg/min 8 MCE of which 5 AE occurred while among patients with normal MTWA and peakVO(2)> or =10 ml/kg/min no event occurred. From multivariate analysis, the combined prognostic value of MTWA and peakVO(2) achieved statistical significance for MCE (p=0.03, HR 0.28, 95% CI 0.12-0.95) and for AE (p=0.05, HR 0.39, 95% CI 0.18-0.99) while MTWA alone was a significant predictor of AE (p=0.04, HR 0.32, 95% CI 0.14-0.93).

CONCLUSIONS

Our results suggest that only the association of MTWA and peakVO(2), but not the two single tests, is a significant prognostic marker of both MCE and AE in DCM patients. However, MTWA alone confirms its predictive power as arrhythmic risk stratifier in this population.

Value of microvolt T-wave alternans for predicting patients who would benefit from implantable cardioverter-defibrillator therapy

Despite considerable progress in the management of coronary artery disease and dilated cardiomyopathy, a substantial proportion of patients remains at the risk of life-threatening arrhythmic events. The Multicenter Automatic Defibrillator Implantation II and Sudden Cardiac Death Heart Failure studies have conclusively demonstrated that prophylactic implantable cardioverter-defibrillator (ICD) therapy reduces mortality among subjects with ischemic and nonischemic cardiomyopathy but at the expense of potentially unnecessary ICD implantation in a large percentage of patients. Microvolt T-wave alternans (MTWA), with a negative predictive value greater than 90%, holds promise for selecting the patients who would likely and patients not likely to benefit from ICD implantation. Accurate identification of high-risk patients by noninvasive MTWA may allow for improved widespread screening for sudden death prevention in the general population.

Can microvolt T-wave alternans testing reduce unnecessary defibrillator implantation?

The Multicenter Automatic Defibrillator Implantation Trial II (MADIT II) and the Sudden Cardiac Death in Heart Failure Trial (SCD-HeFT) have established that patients with a reduced ejection fraction gain an overall mortality benefit from prophylactic implantable cardioverter-defibrillator therapy. Only a small proportion of the patients in these studies, however, have received life-saving therapy from the defibrillator. Because defibrillator therapy is invasive and expensive, patients with a low ejection fraction would benefit from effective risk stratification so that defibrillator therapy was used only in those at significant risk. In this review, we analyze prospective clinical trials that have evaluated microvolt T-wave alternans (MTWA) testing as a predictor of ventricular tachyarrhythmic events in populations of patients similar to those studied in MADIT II or SCD-HeFT; that is, patients with a reduced ejection fraction who were not selected on the basis of a history of ventricular tachyarrhythmias. In these studies, the average annual rate of fatal and nonfatal ventricular tachyarrhythmic events among the patients who tested negative for MTWA was around 1%. This rate is so low that it is unlikely that such patients would benefit from implantable cardioverter-defibrillator therapy. The mortality, moreover, was lower among MTWA-negative patients who did not receive implantable defibrillators than that observed in the MADIT II and SCD-HeFT patients who received implantable cardioverter-defibrillators. In response, patients with a low ejection fraction who are being considered for implantable cardioverter-defibrillator therapy should undergo MTWA testing as part of their evaluation.

Microvolt T-Wave Alternans for the Risk Stratification of Ventricular Tachyarrhythmic Events

OBJECTIVES

The objective of this study was to perform a meta-analysis of the predictive value of microvolt T-wave alternans (MTWA) testing for arrhythmic events in a wide variety of populations.

BACKGROUND

Previous studies describing the use of MTWA as a predictor of ventricular tachyarrhythmic events have been limited by small sample sizes and disparate populations.

METHODS

Prospective studies of the predictive value of exercise-induced MTWA published between January 1990 and December 2004 were retrieved. Data from each article were abstracted independently by two authors using a standardized protocol. Summary estimates of the predictive value of MTWA were made using a random-effects model.

RESULTS

Data were accumulated from 19 studies (2,608 subjects) across a wide range of populations. Overall, the positive predictive value of MTWA for arrhythmic events was 19.3% at an average of 21 months' follow-up (95% confidence interval [CI] 17.7% to 21.0%), the negative predictive value was 97.2% (95% CI 96.5% to 97.9%), and the univariate relative risk of an arrhythmic event was 3.77 (95% CI 2.39 to 5.95). There was no difference in predictive value between ischemic and nonischemic heart failure subgroups. The positive predictive value varied depending on the population of patients studied (p < 0.0001).

CONCLUSIONS

Microvolt T-wave alternans testing has significant value for the prediction of ventricular tachyarrhythmic events; however, there are significant limitations to its use. The predictive value of MTWA varies significantly depending on the population studied. Careful standardization is needed for what constitutes abnormal MTWA. The incremental prognostic value of MTWA when used with other methods of risk stratification is unclear.

Implantable cardioverter defibrillators and cardiac resynchronization therapy in patients with left ventricular dysfunction: randomized trial evidence through 2004

Although many studies have shown that implantable cardioverter defibrillator (ICD) therapy improves the survival of patients with significant left ventricular dysfunction, the magnitude of effectiveness of ICD therapy in clinically defined subgroups remains uncertain. Similarly, although studies have shown an improvement in patients' hemodynamics and quality of life with cardiac resynchronization therapy (CRT), there is a continuing uncertainty about the effect of CRT on patients' survival and the magnitude of improvement in quality of life with this therapy. On August 24, 2004, an ad hoc group of experts representing clinical cardiovascular medicine, biostatistics, economics, and health policy were joined by representatives of the Food and Drug Administration, Centers for Medicare and Medicaid Services (Baltimore, Md), Agency for Healthcare Research and Quality (Rockville, Md), and the device industry for a 1-day round table to review the available clinical trial evidence on the effect of ICD therapy in the primary prevention of sudden cardiac death and the effect of CRT in patients with congestive heart failure. The meeting was organized by the Duke Clinical Research Institute, Durham, NC, and funded in part by the Agency for Healthcare Research and Quality. This document summarizes the evidence reviewed at that meeting and the discussions of that evidence.

T-wave alternans: marker, mechanism, and methodology for predicting sudden cardiac death

Sudden cardiac death (SCD) is a leading cause of cardiovascular mortality. Therefore, identifying patients at highest risk for SCD is crucial. Conventional noninvasive markers of SCD are inadequate because of low positive predictive value. The presence of visible T-wave alternans (TWA) on electrocardiogram often predicts the occurrence of lethal ventricular arrhythmias. Signal processing methods have made it possible to detect microvolt-level and visually inapparent TWA on electrocardiogram. TWA is caused by underlying regional inhomogeneities of ventricular repolarization, which predispose patients to have ventricular arrhythmias. Microvolt TWA provoked either by atrial pacing, pharmacological stress, or exercise is a promising marker of arrhythmia vulnerability. Several large trials have shown TWA to be comparable or superior to other noninvasive markers and electrophysiologic study in the prediction of SCD. The patient populations in these trials include post myocardial infarction, both ischemic and nonischemic heart failure, and suspected arrhythmias. Prospective trials regarding benefits of implantation of cardioverter-defibrillator therapy based on TWA results are ongoing.

Microvolt T-Wave Alternans as a Predictor of Ventricular Tachyarrhythmias

BACKGROUND

Microvolt T-wave alternans (TWA) is reported to be closely associated with sudden cardiac death (SCD) and ventricular tachycardia (VT). Animal experiments revealed that microvolt TWA is highly dependent on heart rate. The purpose of this study was to determine whether patients with TWA at relatively low heart rates have increased vulnerability to ventricular tachyarrhythmias.

METHODS AND RESULTS

Subjects were 248 consecutive patients (158 men, 90 women; mean age, 59+/-17 years) who underwent electrophysiological study from 1997 to 2000. TWA recording was made in sinus rhythm and at atrial pacing rates of 90, 100, 110, and 120 bpm with the Cambridge Heart CH2000 system. Alternans voltage (V(alt)) was measured when the alternans ratio was >3 for a period of >1 minute in VM, X, Y, Z, or 2 adjacent precordial leads. Study end point was the first appearance of VT, ventricular fibrillation (VF), appropriate implantable cardioverter-defibrillator therapy with pacing or shocks, or SCD. During the 37+/-12-month follow-up period, 22 patients had sustained VT, and 5 patients died of SCD. In patients with >1.9-microV V(alt) at rates of 90, 100, and 110 bpm, the incidence of VT/VF/SCD was 56%, 28%, and 18%, respectively. V(alt) of >2.9 microV at a heart rate of 90 bpm had a 70% positive predictive value for VT/VF/SCD. However, when V(alt) was <0.9 microV at a rate of 120 bpm, negative predictive value was 100%.

CONCLUSIONS

Patients with TWA at relatively low heart rates are susceptible to ventricular tachyarrhythmias.

T-wave alternans for risk stratification and prevention of sudden cardiac death

Despite considerable progress in the management of ischemic heart disease, a substantial proportion of patients continue to experience life-threatening arrhythmic events. The Multicenter Automatic Defibrillator Implantation Trial 2 has recently shown the superiority of implantable cardioverter defibrillators (ICDs) over conventional strategies to prevent sudden death in patients with reduced ejection fraction, but at the expense of potentially unnecessary ICD implantation in a large percentage of patients. T-wave alternans (TWA), which reflects alternation of cellular repolarization, results in a substantial increase in dispersion of repolarization, a prerequisite for reentrant arrhythmias. Recent trials, cumulating close to 3000 patients, have established TWA analysis as a powerful tool for arrhythmia prevention. Based on the most recent estimates, at least one third of post-myocardial infarction patients are expected to be tested negative. With a negative predictive value greater than 90%, TWA might allow for targeting of patients most likely to benefit from ICD therapy. Accurate identification of high-risk patients by noninvasive TWA may allow for improved widespread screening for sudden death prevention in the general population.

Catecholamine-provoked microvoltage T wave alternans in genotyped long QT syndrome

Macrovoltage T wave alternans (TWA) has been described in congenital long QT syndrome (LQTS). Microvoltage T wave alternans (microV-TWA) at low heart rate (HR) is a marker of arrhythmogenic risk in many conditions, but its significance in LQTS has not been established. Twenty-three genotypically heterogeneous patients with LQTS and 16 control subjects were studied at rest and during phenylephrine and dobutamine provocation. Genotyping was established by PCR amplification and DNA sequencing of the three most common LQTS genes; KCNQ1/KVLQT1 (LQT1), KCNH2/HERG (LQT2), and SCN5A (LQT3). microV-TWA was determined using Fast Fourier transform. Precluded by ectopy, microV-TWA could not be assessed in 8 of 23 patients with LQTS. In the remaining 15 patients with LQTS, microV-TWA occurred at lower HR in LQTS than in controls (117 +/- 49 vs 153 +/- 37 beats/min; P < 0.05). Patients with LQTS developed microV-TWA at HR < 150 beats/min more often than controls (10/15 vs 2/16; P = 0.003). However, microV-TWA was not detected in the 3 individuals with a history of out-of-hospital cardiac arrest including a 14-year-old male with an F339del-KVLQT1 mutation (LQT1) who had dobutamine-provoked polymorphic ventricular tachycardia requiring external defibrillation. Catecholamine-provoked microV-TWA occurs at lower HR in patients with LQTS than in healthy people but does not identify high risk subjects.

Effect of Long-Term Beta-Blocker Therapy on Microvolt-Level T-Wave Alternans in Association With the Improvement of the Cardiac Sympathetic Nervous System and Systolic Function in Patients With Non-Ischemic Heart Disease

The purpose of this study was to test a hypothesis that T-wave alternans (TWA) is improved in association with an improvement in cardiac sympathetic nervous system and systolic function by oral beta-blocker therapy in patients with non-ischemic heart disease (NIHD). TWA testing, (123)I-metaiodobenzylguanidine (MIBG) imaging and echocardiography were performed at the baseline and 3 months after beta-blocker therapy in 26 patients with NIHD and positive TWA. The alternans voltage (V(alt)), the heart-to mediastinal-ratio on the early (e-H/M) and delayed (d-H/M) images, the washout rate (WR), the left ventricular ejection fraction (LVEF), and the calculated rate of change by beta-blocker therapy in each parameter (ie, deltaV(alt), deltae-H/M, deltad-H/M, deltaWR and deltaLVEF) were measured. After therapy, TWA turned negative in 8 patients (group A) and remained positive in 18 (group B); V(alt) was significantly decreased in group B (p<0.001). In group A, e-H/M, d-H/M and LVEF were significantly increased (e-H/M: p<0.05, d-H/M and LVEF: p<0.01), as were e-H/M and LVEF in group B (p<0.05). There were significant correlations between deltaV(alt) and deltae-H/M (r=-0.61, p<0.01), deltad-H/M (r=-0.82, p<0.0001), deltaWR (r=0.60, p<0.01) and deltaLVEF (r=-0.70, p<0.01). In patients with NIHD, the TWA is improved in association with the improvement in cardiac sympathetic nervous system abnormalities and left ventricular systolic dysfunction by beta-blocker therapy.

Clinical significance of T-wave alternans in hypertrophic cardiomyopathy

The clinical significance of T-wave alternans (TWA) in hypertrophic cardiomyopathy (HCM) is unclear, so SV1+RV5 and QT dispersion on 12-lead electrocardiograms (ECG), the parameters of the left ventricle on echocardiography and the family history of HCM and sudden death were investigated in 53 patients with HCM who experienced TWA. The maximal numbers of successive ventricular ectopic beats (max VE) and nonsustained ventricular tachycardia (NSVT) were measured by Holter monitoring. In 13 patients, genetic abnormalities were examined. In 22 patients, the hypertrophy of myocytes, disarray and fibrosis were histopathologically examined using a scoring method. TWA was positive in 27 patients (TWA+ group), negative in 14 (TWA- group) and indeterminate in 12. The ECG and echocardiographic parameters, family history and genetic abnormalities did not significantly differ between the TWA+ and TWA- groups. Max VE, the percentage of patients with NSVT and disarray score in the TWA+ group were significantly higher than those in the TWA- group (3.6+/-3.6 vs 1.3+/-0.7, 37% vs 0%, 1.9+/-1.1 vs 0.7+/-0.5; p<0.05). TWA in HCM correlates with histopathological changes, especially disarray and ventricular tachyarrhythmia, and measuring it may be a noninvasive means of detecting high-risk patients with HCM.

Onset heart rate of microvolt-level T-wave alternans provides clinical and prognostic value in nonischemic dilated cardiomyopathy

OBJECTIVES

This study was designed to determine the prognostic value of onset heart rate (OHR) in T-wave alternans (TWA) in patients with nonischemic dilated cardiomyopathy (DCM).

BACKGROUND

One of the current major issues in DCM is to prevent sudden cardiac death (SCD). However, the value of the OHR of TWA as a prognostic indicator in DCM remains to be elucidated.

METHODS

We prospectively investigated 104 patients with DCM undergoing TWA testing. The end point of this study was defined as SCD, documented sustained ventricular tachycardia/ventricular fibrillation. Relations between clinical parameters and subsequent outcome were evaluated.

RESULTS

Forty-six patients presenting with TWA were assigned to one of the following two subgroups according to OHR for TWA of < or = 100 beats/min: group A (n = 24) with OHR < or = 100 beats/min and group B (n = 22) with 100 < OHR < or = 110 beats/min. T-wave alternans was negative in 37 patients (group C) and indeterminate in 21 patients. The follow-up result comprised 83 patients with determined TWA. During a follow-up duration of 21 +/- 14 months, there was a total of 12 arrhythmic events, nine of which included three SCDs in group A, two in group B and one in group C. The forward stepwise multivariate Cox hazard analysis revealed that TWA with an OHR < or = 100 beats/min and left ventricular ejection fraction were independent predictors of these arrhythmic events (p = 0.0001 and p = 0.0152, respectively).

CONCLUSIONS

The OHR of TWA is of additional prognostic value in DCM.

Clinical usefulness of the combination of T-wave alternans and late potentials for identifying high-risk patients with moderately or severely impaired left ventricular function

Ventricular tachyarrhythmia (VT) is an independent risk factor for an increased overall mortality in patients with impaired left ventricular (LV) function, but there is not an established noninvasive tool to detect such patients. The present study aimed to clarify the most useful noninvasive approach for identification of patients with moderately or severely impaired LV function complicated by VT. Sixty-seven patients in New York Heart Association (NYHA) classes I-III with an LV ejection fraction (LVEF) less than 40% and an LV end-diastolic dimension (LVDD) of at least 55 mm on echocardiography were enrolled. Impaired LV function was caused by either ischemic (n=30) or nonischemic dilated cardiomyopathy (n=37). T-wave alternans (TWA), QT dispersion (QTD), and late potentials (LP) on signal-averaged electrocardiography were sequentially determined without using antiarrhythmic drugs. VT was defined as more than 6 consecutive ventricular ectopic beats. The mean NYHA class was 1.9+/-0.7, mean LVEF was 31+/-8%, and mean LVDD was 65+/-10mm. A history of VT was present in 26 of the patients (39%). Univariate and multivariate logistic analysis showed that TWA and LP were closely related to VT, whereas NYHA> or =III, LVEF<30%, LVDD> or =70mm, and QTD> or =90ms were not. The combination of TWA and LP had the most significant value (p=0.0004, odds ratio=8.44) by univariate analysis, and only this combination had significant value in multivariate analysis (p=0.04). Therefore, the combination of TWA and LP could be a useful index for identifying those patients with impaired LV function who are at risk for VT.