Prognostic utility of microvolt T-wave alternans in risk stratification of patients with ischemic cardiomyopathy.

OBJECTIVES: The purpose of this study was to assess if microvolt T-wave alternans (MTWA) is an independent predictor of mortality in patients with ischemic cardiomyopathy. BACKGROUND: Microvolt T-wave alternans has been proposed as an effective tool for identifying high-risk patients with ischemic cardiomyopathy who are likely to benefit from implantable cardioverter-defibrillator (ICD) therapy. However, earlier studies have been limited in their ability to control for baseline differences between MTWA-negative and -non-negative (positive and indeterminate) patients. METHODS: We enrolled 768 consecutive patients with ischemic cardiomyopathy (left ventricular ejection fraction < or =35%) and no prior history of ventricular arrhythmia. All patients underwent baseline MTWA testing and were classified as MTWA negative or non-negative. Multivariable Cox regression analyses, stratified by ICD status, were used to determine the association between MTWA testing and mortality after adjusting for demographic, clinical, and treatment differences between MTWA-negative and -non-negative patients. RESULTS: We identified 514 (67%) patients with a non-negative MTWA test. After multivariable adjustment, a non-negative MTWA test was associated with a significantly higher risk for all-cause (stratified hazard ratio [HR] = 2.24 [95% confidence interval 1.34 to 3.75]; p = 0.002) and arrhythmic mortality (stratified HR = 2.29 [1.00 to 5.24]; p = 0.049) but not for nonarrhythmic mortality (stratified HR = 1.77 [0.84 to 3.74]; p = 0.13). In subgroup analyses, a non-negative MTWA test was also associated with a higher risk for all-cause mortality in patients with ejection fractions < or =30% (stratified HR = 2.10 [1.18 to 3.73]; p = 0.01) and after excluding those with indeterminate MTWA tests (stratified HR = 2.08 [1.18 to 3.66]; p = 0.01). CONCLUSIONS: Microvolt T-wave alternans is a strong and independent predictor of all-cause and arrhythmic mortality in patients with ischemic cardiomyopathy.     

Usefulness of microvolt T-wave alternans on predicting outcome in patients with ischemic cardiomyopathy with and without defibrillators

Microvolt T-wave alternans (MTWA) was proposed as an effective tool to identify high-risk patients with ischemic cardiomyopathy. However, previous studies suggested that the prognostic utility of MTWA may be limited to only patients with normal QRS duration. It therefore was assessed whether MTWA and QRS duration >120 ms independently predict mortality in patients with ischemic cardiomyopathy and whether the prognostic utility of MTWA differs by QRS duration. A total of 768 consecutive patients with ischemic cardiomyopathy (left ventricular ejection fraction < or =35%) and no history of ventricular arrhythmia were enrolled, of whom 514 (67%) screened MTWA non-negative (positive or indeterminate) and 223 (29%) had a QRS >120 ms on resting electrocardiogram. After multivariable adjustment, a non-negative MTWA test result was associated with a significantly higher risk for all-cause mortality in patients without an implantable cardioverter-defibrillator (ICD) (hazard ratio [HR] 2.27, 95% confidence interval [CI] 1.22 to 4.24, p = 0.01) and for all-cause mortality and appropriate ICD shocks in patients with an ICD (HR 2.42, 95% CI 1.07 to 5.41, p = 0.04). In contrast, a QRS >120 ms was not associated with all-cause mortality and ICD shocks in patients without (HR 0.96, 95% CI 0.52 to 1.75, p = 0.88) or with an ICD (HR 1.25, 95% CI 0.76 to 2.08, p = 0.40). No significant interaction was found between MTWA and QRS >120 ms (non-ICD p = 0.19, ICD p = 0.73). In conclusion, MTWA, but not QRS duration, predicted mortality outcomes in patients with ischemic cardiomyopathy. Moreover, the prognostic utility of MTWA did not appear to differ by QRS duration.     

Cost-effectiveness of a microvolt T-wave alternans screening strategy for implantable cardioverter-defibrillator placement in the MADIT-II-eligible population.

OBJECTIVES: This study was designed to compare the cost-effectiveness of implantable cardioverter-defibrillator (ICD) placement with and without risk stratification with microvolt T-wave alternans (MTWA) testing in the MADIT-II (Second Multicenter Automatic Defibrillator Implantation Trial) eligible population. BACKGROUND: Implantable cardioverter-defibrillators have been shown to prevent mortality in the MADIT-II population. Microvolt T-wave alternans testing has been shown to be effective in risk stratifying MADIT-II-eligible patients. METHODS: On the basis of published data, cost-effectiveness of three therapeutic strategies in MADIT-II-eligible patients was assessed using a Markov model: 1) ICD placement in all; 2) ICD placement in patients testing MTWA non-negative;, and 3) medical management. Outcomes of expected cost, quality-adjusted life-years (QALYs), and incremental cost-effectiveness were determined for patient lifetime. RESULTS: Under base-case assumptions, providing ICDs only to those who test MTWA non-negative produced a gain of 1.14 QALYs at an incremental cost of 55,700 dollars when compared to medical therapy, resulting in an incremental cost-effectiveness ratio (ICER) of 48,700 dollars/QALY. When compared with a MTWA risk-stratification strategy, placing ICDs in all patients resulted in an ICER of 88,700 dollars/QALY. Most (83%) of the potential benefit was achieved by implanting ICDs in the 67% of patients who tested MTWA non-negative. Results were most sensitive to the effectiveness of MTWA as a risk-stratification tool, MTWA negative screen rate, cost and efficacy of ICD therapy, and patient risk for arrhythmic death. CONCLUSIONS: Risk stratification with MTWA testing in MADIT-II-eligible patients improves the cost-effectiveness of ICDs. Implanting defibrillators in all MADIT-II-eligible patients, however, is not cost-effective, with one-third of patients deriving little additional benefit at great expense.     

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.     

Microvolt T-wave alternans and the risk of death or sustained ventricular arrhythmias in patients with left ventricular dysfunction.

OBJECTIVES: This study hypothesized that microvolt T-wave alternans (MTWA) improves selection of patients for implantable cardioverter-defibrillator (ICD) prophylaxis, especially by identifying patients who are not likely to benefit. BACKGROUND: Many patients with left ventricular dysfunction are now eligible for prophylactic ICDs, but most eligible patients do not benefit; MTWA testing has been proposed to improve patient selection. METHODS: Our study was conducted at 11 clinical centers in the U.S. Patients were eligible if they had a left ventricular ejection fraction (LVEF) < or =0.40 and lacked a history of sustained ventricular arrhythmias; patients were excluded for atrial fibrillation, unstable coronary artery disease, or New York Heart Association functional class IV heart failure. Participants underwent an MTWA test and then were followed for about two years. The primary outcome was all-cause mortality or non-fatal sustained ventricular arrhythmias. RESULTS: Ischemic heart disease was present in 49%, mean LVEF was 0.25, and 66% had an abnormal MTWA test. During 20 +/- 6 months of follow-up, 51 end points (40 deaths and 11 non-fatal sustained ventricular arrhythmias) occurred. Comparing patients with normal and abnormal MTWA tests, the hazard ratio for the primary end point was 6.5 at two years (95% confidence interval 2.4 to 18.1, p < 0.001). Survival of patients with normal MTWA tests was 97.5% at two years. The strong association between MTWA and the primary end point was similar in all subgroups tested. CONCLUSIONS: Among patients with heart disease and LVEF < or =0.40, MTWA can identify not only a high-risk group, but also a low-risk group unlikely to benefit from ICD prophylaxis.     

"Indeterminate" microvolt T-wave alternans tests predict high risk of death or sustained ventricular arrhythmias in patients with left ventricular dysfunction.

OBJECTIVES: This study tested the hypothesis that an "indeterminate" microvolt T-wave alternans (MTWA) test, when due to ectopy, unsustained MTWA, or low exercise heart rate (HR), has prognostic significance similar to a positive MTWA test. BACKGROUND: MTWA testing, used to stratify risk of sudden or total mortality in patients with structural heart disease, has been limited by a substantial number of "indeterminate" tests. Indeterminate tests are due to patient factors--excessive ventricular ectopy during exercise, unsustained MTWA, or failure to achieve a HR of 105 beats/min for 1 min--or technical factors such as a noisy recording or an exercise protocol that causes an excessively rapid rise in HR. METHODS: Patients in sinus rhythm with left ventricular ejection fraction < or =0.40 underwent MTWA exercise tests, analyzed with the spectral method and classified by a computerized interpretation algorithm. The primary end point was all-cause mortality or documented non-fatal sustained ventricular arrhythmia (SVA). "Indeterminate" tests were reviewed jointly by 2 readers blinded to subsequent events to determine the primary reason for indeterminacy. RESULTS: Participants (N = 549) were 56 +/- 13 years and 71% male; 49% had ischemic cardiomyopathy. There were 40 deaths and 11 non-fatal SVA. Most (94%) indeterminate results were due to patient factors. The 2-year rate for death or SVA was 17.8% in patients with an "indeterminate" MTWA test compared with 12.3% in those with a positive test. CONCLUSIONS: In patients with left ventricular dysfunction, an "indeterminate" MTWA test due to patient factors predicted death or SVA at least as well as a positive test.     

Predictive value of microvolt T-wave alternans in patients with left ventricular dysfunction.

OBJECTIVES: The purpose of this study was to prospectively evaluate the utility of microvolt T-wave alternans (TWA) in predicting arrhythmia-free survival and total mortality in patients with left ventricular (LV) dysfunction. BACKGROUND: Microvolt TWA has been proposed as a useful tool in identifying patients unlikely to benefit from prophylaxis with implantable cardioverter-defibrillator (ICD) prophylaxis. METHODS: We evaluated 286 patients with an LV ejection fraction 相似文献   

Quantitative assessment of microvolt T-wave alternans in patients with congestive heart failure

INTRODUCTION: T-wave alternans has been shown to be linked to the genesis of ventricular tachyarrhythmias. Currently, only qualitative assessment of microvolt T-wave alternans (MTWA) is recommended in clinical practise. Whether quantitative assessment of MTWA yields complementary information is unknown. METHODS AND RESULTS: Noninvasive MTWA determination was performed in 204 consecutive patients with ischemic or nonischemic cardiomyopathy. Of those, 100 tested MTWA positive. In these recordings, MTWA magnitude was quantitatively assessed (alternans voltage, V(alt)). Patients were followed for a mean of 17 months. Ventricular tachyarrhythmic events constituted the study endpoint. Patients with nonischemic cardiomyopathy had a higher V(alt) than patients with ischemic cardiomyopathy (10.3 +/- 9.2 [median 7.2] vs 6.2 +/- 3.2 [median 4.6] microV; P = 0.007). The number of MTWA-positive ECG leads was also higher in patients nonischemic cardiomyopathy (7.3 +/- 2.4 [median 8] vs 6.0 +/- 2.5 [median 6]; P = 0.016). Patients who suffered an arrhythmic event during follow-up had higher MTWA voltages (10.8 +/- 10.0 [median 8.8] vs 7.4 +/- 5.7 [median 6.4] microV; P = 0.05) a higher number of MTWA-positive ECG leads (7.6 +/- 2.4 [median 8] vs 6.4 +/- 2.5 [median 6]; P = 0.05) compared to patients with an uncomplicated course. CONCLUSION: Patients with nonischemic cardiomyopathy and patients with tachyarrhythmic complications have more extensive MTWA possibly reflecting more extensive myocardial damage and a higher arrhythmia propensity.     

微伏级T波电交替对未植入ICD的心力衰竭患者危险度预测的Meta分析

目的：用Meta分析方法系统性评价微伏级T波电交替（MTWA）对未植入体内自动除颤器（ICD）的心衰患者恶性心律失常和死亡的预测价值。方法检索1990年1月~2013年6月关于运动负荷试验时异常的MTWA对未植入ICD的心衰患者预后预测的前瞻性临床研究。通过χ2统计量结合I2统计量进行异质性检验,用倒方差法固定效应模型分析MTWA对恶性心律失常和死亡的风险,得到合并效应指标风险比（hazard ratio,HR）及其95％可信区间（CI）。结果共有7项研究被纳入,总样本量2953人。其中662人MTWA阳性,1705人MTWA阴性,340人MTWA不确定,246人MTWA非阴性（包括阳性和不确定性）。和MTWA阴性的患者相比较,MTWA异常的患者发生恶性心律失常和死亡的危险度增加（HR为4.51,95%CI：2.28～8.89,P＜0.001）。结论 MTWA检测进行危险分层的评估对未植入ICD的心衰患者恶性心律失常事件和死亡有预测价值。     

Usefulness of microvolt T-wave alternans to predict outcomes in patients with ischemic cardiomyopathy beyond one year

Previous studies have demonstrated that microvolt T-wave alternans (MTWA) screening effectively risk-stratifies patients with ischemic cardiomyopathy. Whether the prognostic utility of MTWA diminishes over 3 years of follow-up remains unknown. In this study, a prospective cohort of 768 patients with ischemic cardiomyopathy (left ventricular ejection fraction <35%) and no previous sustained ventricular arrhythmia was developed, of whom 514 (67%) screened MTWA nonnegative (positive and indeterminate). The mean follow-up period was 18 +/- 11 months. The primary end point was all-cause mortality and appropriate implantable cardioverter-defibrillator shocks. Stratified Cox regression analyses (by implantable cardioverter-defibrillator status) estimated the predictive power of MTWA within each year of follow-up and determined whether this diminished over time. There were 99 deaths (MTWA negative: 21 [8.3%]; MTWA nonnegative: 78 [15.2%]) and 33 appropriate implantable cardioverter-defibrillator shocks (MTWA negative: 3 [4.0%]; MTWA nonnegative: 30 [9.5%]). After multivariate adjustment, a nonnegative MTWA test result was associated with a greater than twofold increased risk for events in each of the 3 years of follow-up (year 1: stratified hazard ratio 2.19, 95% confidence interval 1.10 to 4.34, p = 0.03; year 2: stratified hazard ratio 3.36, 95% confidence interval 1.28 to 8.83, p = 0.01; year 3: stratified hazard ratio 2.06, 95% confidence interval 0.81 to 5.22, p = 0.13). There were no significant interactions between the time periods (year 1 vs year 2: p = 0.47; year 1 vs year 3: p = 0.92). In conclusion, MTWA reliably and consistently predicts mortality and arrhythmic risk throughout the first 2 to 3 years of follow-up. Although these findings need further validation, they suggest that rescreening with MTWA may not need to be performed more frequently than once every 2 years.     

Effectiveness of implantable cardioverter-defibrillators in patients with ischemic heart disease and left ventricular dysfunction

BACKGROUND: Implantable cardioverter-defibrillators (ICDs) have been shown in primary prevention efficacy trials to reduce mortality in patients with ischemic heart disease and left ventricular dysfunction. To investigate the generalizabilty of this mortality reduction, we examined the effectiveness of ICDs in clinical practice. METHODS: We developed a prospective multicenter cohort of 770 patients with ischemic left ventricular dysfunction (ejection fraction < or =35%) and without a history of ventricular arrhythmia, of whom 395 (52%) received ICDs. Mean +/- SD follow-up was 27 +/- 12 months. We assessed the degree to which ICDs decreased mortality risk using Cox proportional hazards analyses that controlled for clinical predictors of death, receipt of ICD (a propensity score analysis), and predictors of arrhythmic death (including electrophysiologic variables). RESULTS: Multivariate Cox analyses showed that those with ICDs had significantly lower all-cause mortality (hazard ratio [HR], 0.53; 95% confidence interval [CI], 0.33-0.86). This mortality reduction was mediated through dramatically lower arrhythmia-related mortality (HR, 0.35; 95% CI, 0.17-0.73), with no significant effect on cardiovascular nonarrhythmic (HR, 0.81; 95% CI, 0.34-1.96) and noncardiovascular (HR, 0.76; 95% CI, 0.29-2.05) mortality. No differences were found between the ICD and non-ICD groups for a composite outcome of all-cause mortality, appropriate ICD shocks, or documented symptomatic ventricular arrhythmia, which suggests that the 2 groups had similar baseline risk for life-threatening arrhythmic events (HR, 0.96; 95% CI, 0.63-1.45). CONCLUSION: In clinical practice, ICDs appear to reduce all-cause and arrhythmic rates of mortality at levels similar to those found in primary prevention trials.     

Microvolt T-wave alternans for the risk stratification of ventricular tachyarrhythmic events: a meta-analysis

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.     

Usefulness of microvolt T-wave alternans for prediction of ventricular tachyarrhythmic events in patients with dilated cardiomyopathy: results from a prospective observational study

OBJECTIVES: This study was designed to evaluate the ability of microvolt-level T-wave alternans (MTWA) to identify prospectively patients with idiopathic dilated cardiomyopathy (DCM) at risk of ventricular tachyarrhythmic events and to compare its predictive accuracy with that of conventional risk stratifiers. BACKGROUND: Patients with DCM are at increased risk of sudden death from ventricular tachyarrhythmias. At present, there are no established methods of assessing this risk. METHODS: A total of 137 patients with DCM underwent risk stratification through assessment of MTWA, left ventricular ejection fraction, baroreflex sensitivity (BRS), heart rate variability, presence of nonsustained ventricular tachycardia (VT), signal-averaged electrocardiogram, and presence of intraventricular conduction defect. The study end point was either sudden death, resuscitated ventricular fibrillation, or documented hemodynamically unstable VT. RESULTS: During an average follow-up of 14 +/- 6 months, MTWA and BRS were significant univariate predictors of ventricular tachyarrhythmic events (p < 0.035 and p < 0.015, respectively). Multivariate Cox regression analysis revealed that only MTWA was a significant predictor. CONCLUSIONS: Microvolt-level T-wave alternans is a powerful independent predictor of ventricular tachyarrhythmic events in patients with DCM.     

Predictors of death and occurrence of appropriate implantable defibrillator therapies in patients with ischemic cardiomyopathy

Most patients with chronic ischemia and an implantable cardiac defibrillator (ICD) for primary prevention do not experience therapies for ventricular arrhythmias on follow-up. The present study aimed to identify independent clinical, electrocardiographic, and echocardiographic predictors of death and occurrence of ICD therapy in patients with chronic ischemic cardiomyopathy and ICD for primary prevention. A total of 424 patients with chronic ischemic cardiomyopathy, ejection fraction ≤ 35%, and New York Heart Association (NYHA) class ≥ II were recruited. All patients underwent echocardiography before ICD insertion. Primary outcome was all-cause mortality; secondary outcome was occurrence of appropriate ICD therapy on follow-up. Primary and secondary outcomes occurred in 84 and 95 patients, respectively. Patients who died were more likely to have diabetes (hazard ratio [HR] 1.67, 95% confidence interval [CI] 1.00 to 2.79, p = 0.049), higher NYHA class (HR 1.96, 95% CI 1.15 to 3.33, p = 0.013), lower peri-infarct strain on echocardiogram (HR 1.25, 95% CI 1.07 to 1.46, p = 0.005), and lower glomerular filtration rate (HR 1.01, 95% CI 1.00 to 1.03, p = 0.022). Only peri-infarct strain (HR 1.22, 95% CI 1.09 to 1.36, p < 0.001) predicted the occurrence of ICD therapy on follow-up. In conclusion, in chronic ischemic patients with an ICD for primary prevention, the presence of diabetes, renal dysfunction, higher NYHA class, and impaired peri-infarct zone function were predictors of all-cause mortality. In contrast, only impaired peri-infarct zone function determined the occurrence of appropriate ICD therapy on follow-up.     

Prognostic value of T-wave alternans in patients with heart failure due to nonischemic cardiomyopathy: results of the ALPHA Study.

OBJECTIVES: The aim of this study was to assess the prognostic value of T-wave alternans (TWA) in New York Heart Association (NYHA) functional class II/III patients with nonischemic cardiomyopathy and left ventricular ejection fraction (LVEF) < or =40%. BACKGROUND: There is a strong need to identify reliable risk stratifiers among heart failure candidates for implantable cardioverter-defibrillator (ICD) prophylaxis. T-wave alternans may identify low-risk subjects among post-myocardial infarction patients with depressed LVEF, but its predictive role in nonischemic cardiomyopathy is unclear. METHODS: Four hundred forty-six patients were enrolled and followed up for 18 to 24 months. The primary end point was the combination of cardiac death + life-threatening arrhythmias; secondary end points were total mortality and the combination of arrhythmic death + life-threatening arrhythmias. RESULTS: Patients with abnormal TWA (65%) compared with normal TWA (35%) tests were older (60 +/- 13 years vs. 57 +/- 12 years), were more frequently in NYHA functional class III (22% vs. 19%), and had a modestly lower LVEF (29 +/- 7% vs. 31 +/- 7%). Primary end point rates in patients with abnormal and normal TWA tests were 6.5% (95% confidence interval [CI] 4.5% to 9.4%) and 1.6% (95% CI 0.6% to 4.4%), respectively. Unadjusted and adjusted hazard ratios were 4.0 (95% CI 1.4% to 11.4%; p = 0.002) and 3.2 (95% CI 1.1% to 9.2%; p = 0.013), respectively. Hazard ratios for total mortality and for arrhythmic death + life-threatening arrhythmias were 4.6 (p = 0.002) and 5.5 (p = 0.004), respectively; 18-month negative predictive values for the 3 end points ranged between 97.3% and 98.6%. CONCLUSIONS: Among NYHA functional class II/III nonischemic cardiomyopathy patients, an abnormal TWA test is associated with a 4-fold higher risk of cardiac death and life-threatening arrhythmias. Patients with normal TWA tests have a very good prognosis and are likely to benefit little from ICD therapy.     

Enhancing Specificity Without Sacrificing Sensitivity: Potential Benefits of Using Microvolt T-Wave Alternans Testing to Risk Stratify the MADIT-II Population

The MADIT-II study (Moss et al., N Engl J Med 2002;346:877-883) demonstrated that implantation of a cardioverter/defibrillator (ICD) reduced mortality from 19.8% to 14.2% during 20 months of follow-up in patients with prior myocardial infarction and left ventricular ejection fraction 相似文献   

Microvolt T-wave alternans for risk stratification of cardiac events in ischemic cardiomyopathy: A meta-analysis

Background

The ability of microvolt T-wave alternans (MTWA) for risk stratification of cardiac events in patients with ischemic cardiomyopathy (ICM) has not been well established.

Methods

The authors systematically reviewed current literature and carried out a meta-analysis to determine the ability of MTWA to predict the outcome severity after ICM. Major endpoints include composite endpoint of cardiac mortality and severe arrhythmic events in primary prevention of patients with ICM, as well as all-cause mortality (cardiac death, and/or non-cardiac death).

Results

Seven trials were included by using MTWA for risk stratification of cardiac events in 3385 patients with ICM. All patients were distributed into two groups according to the results of MTWA tests: non-negative group included positive and indeterminate, and negative group. Compared with the negative group, non-negative group showed increased rates of cardiac mortality or severe arrhythmic events (RR = 1.65, 95%CrI = 1.32, 2.071), sudden cardiac death (SCD) (RR = 2.04 95%CrI = 1.11, 3.75), and all-cause mortality (RR = 2.11, 95%CrI = 1.60, 2.79). The funnel plot revealed that there might be bias within current publications. The fail-safe number of composite endpoint and all-cause mortality was 14.42 and 18.93, respectively (when P = 0.01). The fail-safe number of SCD was 1.07 (when P = 0.05), which may be caused by the small case number of included studies and some patients with ICD included.

Conclusions

The non-negative group of MTWA had a nearly double risk of severe outcomes compared with the negative group. Therefore, MTWA represents a potential useful tool for judging the severity of ICM.     

Sudden death prophylaxis in heart failure

Sudden cardiac death (SCD) is the leading cause of mortality in heart failure (HF). Today the implantable cardioverter-defibrillator (ICD) has become a commonplace therapy around the world for patients with both ischemic and non-ischemic cardiomyopathy and an ejection fraction (EF) < or = 35%. However, EF alone does not discriminate between the modes of death from HF (sudden arrhythmic death vs. non-sudden death). Other risk statifiers, such as electrophysiologic study and microvolt T-wave alternans testing, should therefore be used in the appropriate settings to minimize the number of unnecessary device implants. In addition, left ventricular mechanical dyssynchrony has now become recognized as an additional major marker of cardiac mortality. Its assessment should entail echocardiography rather than measurement of the QRS duration. This will allow us to better integrate the ability of cardiac resynchronization therapy (CRT) in enhancing cardiac function with the ability of an ICD in preventing SCD. This review aims to: 1) give a synthesis of the published evidence regarding the value of implantable ICDs and CRT in the primary prophylaxis of SCD in HF; 2) discuss controversial clinical issues in this area; and 3) recommend practical device-based management strategies.     

CRT32: THE CRP PREIMPLANTATION LEVELS COULD PREDICT THE OUTCOME OF IMPLANTABLE CARDIOVERTER DEFIBRILLATORS

BACKGROUND: The C-reactive protein (CRP) has been advocated as a predictorof mortality in Chronic Heart Failure. There are some reportsthat its production may be associated with electrophysiologicalabnormalities. We hypothesized that this marker levels may bepredict the outcome and the future shocks in patients with cardiomyopathyand implantable cardioverter defibrillators (ICDs). Thus, theaim of our study was to elucidate if a pre-implant CRP levelwill predict the prevalence of the future ICD shocks. METHODS: We included 65 consecutive patients with cardiomyopathy underwentfirs-time ICD implantation. Serum CRP levels were obtained themorning prior to ICD implant. We followed the patients up every3 months post-implantation for device interrogation to detectshocks delivery. We analyzed only patients receiving appropriateshocks, based on stored electrograms. Mean follow-up was 225 months. RESULTS: Of the patients included 65% had ischemic cardiomyopathy,23%dilated cardiomypathy and 12% other myopathies. The mean EFwas 2812% . A preimplant history of sustained ventricular arrhythmiahad 67% of patients, non-sustained 28% and cardiac arrest 5%of patients. During the follow-up 28 patients (43%) receivedappropriate ICD shocks (mean 69 shocks per patient). The levelsof basic biomarkers (serum creatinine, electrolytes, uric acid,hepatic enzymes), the usage of beta-blockers, statins, ACE-inhibitorsand spironolactone did not differ between shocks and non shockspatients. By univariate analysis, the ejection fraction (p=0.023),CRP levels (p=0.016) and not taking amiodarone (p=0.021) wererisk factors for ICD shock. By multivariate analysis using logisticregression, only CRP was a significant predictor (odds ratio1.7 per CRP, 95% CI=1.01-1.22, p=0.018). Mean CRP at implantationwas 111.87mg/dl versus 1.80.04mg/dl in shock and no-shockpatients respectively p=0.014). CONCLUSIONS: The pre-implant CRP level is independent predictor of ICD shockin patients with cardiomyopathies underwent first-time ICD implantation.     

扩张型心肌病患者微伏级T波电交替检测分析

目的研究扩张型心肌病患者微伏级T波电交替(MTWA)的发生情况及与心率的关系。方法对31例扩张型心肌病患者用频谱法检测MTWA,分析扩张型心肌病MTWA的阳性率及不确定结果的原因,静息和运动时MTWA的发生情况,心率与交替压(Valt)的关系。结果①扩张型心肌病患者MTWA的阳性率为35.48%;②扩张型心肌病者,运动时的心率大于静息时,运动时各导联的Valt值大于静息时(P均<0.01)。静息时MTWA阳性2例,运动时MTWA阳性11例,运动时MTWA的阳性率高于静息时(35.48%vs 6.45%,P<0.01);③心率与综合导联Valt呈正相关,随心率的增加,Valt增大(r=0.984,P<0.01)。结论①扩张型心肌病患者MTWA阳性率高于正常人;②MTWA的发生与心率相关,随心率增快,Valt增大,MTWA阳性检出率增加。