Long-Term Outcomes of Implantable Cardioverter-Defibrillator Therapy in the SCD-HeFT

BACKGROUND

The SCD-HeFT (Sudden Cardiac Death in Heart Failure Trial) randomized 2,521 patients with moderate heart failure (HF) to amiodarone, placebo drug, or implantable cardioverter-defibrillator (ICD) therapy. Original trial follow-up ended October 31, 2003. Over a median 45.5-month follow-up, amiodarone, compared with placebo, did not affect survival, whereas randomization to an ICD significantly decreased all-cause mortality by 23%.

OBJECTIVES

This study sought to describe the extended treatment group survival of the SCD-HeFT cohort.

METHODS

Mortality outcomes for the 1,855 patients alive at the end of the SCD-HeFT trial were collected between 2010 and 2011. These data were combined with the 666 deaths from the original study to compare long-term outcomes overall and for key pre-specified subgroups.

RESULTS

Median (25th to 75th percentiles) follow-up was 11.0 (10.0 to 12.2) years. On the basis of intention-to-treat analysis, the ICD group had overall survival benefit versus placebo drug (hazard ratio [HR]: 0.87; 95% confidence interval [CI]: 0.76 to 0.98; p = 0.028). When treatment benefit was examined as a function of time from randomization, attenuation of the ICD benefit was observed after 6 years (p value for the interaction = 0.0015). Subgroup analysis revealed long-term ICD benefit varied according to HF etiology and New York Heart Association (NYHA) functional class: ischemic HF HR: 0.81; 95% CI: 0.69 to 0.95; p = 0.009; nonischemic HF HR: 0.97; 95% CI: 0.79 to 1.20; p = 0.802; NYHA functional class II HR: 0.76; 95% CI: 0.65 to 0.90; p = 0.001; NYHA functional class III HR: 1.06; 95% CI: 0.86 to 1.31; p = 0.575.

CONCLUSIONS

Follow-up of SCD-HeFT patients to 11 years demonstrated heterogenous treatment-related patterns of long-term survival with ICD benefit most evident at 11 years for ischemic HF patients and for those with NYHA functional class II symptoms at trial enrollment. (SCD-HeFT 10 Year Follow-up [SCD-HeFT10 Yr]; NCT01058837).

Comparative prognostic significance of simultaneous versus independent resolution of ST segment depression relative to ST segment elevation during acute myocardial infarction

OBJECTIVES

We sought to determine the prognostic significance of simultaneous versus independent resolution of ST segment depression that occurs concomitant with ST segment elevation during acute myocardial infarction (AMI).

BACKGROUND

ST segment depression in leads other than those showing ST segment elevation during AMI is a common phenomenon. Whether this indicates adverse outcomes remains controversial. We hypothesized that the timing of ST segment depression resolution relative to ST segment elevation resolution might differentiate between a high risk group and a low risk group of patients.

METHODS

Continuous 12-lead ST segment monitoring was performed after thrombolytic therapy for AMI in 413 patients, 261 of whom met technical criteria for analysis. Blinded analysis of ST segment depression resolution patterns was used to group patients as follows: 1) no ST segment depression at any time (control group); 2) ST segment depression resolving simultaneously with ST segment elevation (simultaneous group); and 3) ST segment depression persisting after ST segment elevation resolution (independent group). These patterns were correlated with the outcomes-recurrent angina, reinfarction, heart failure and death-using chi-square analysis and the Fisher exact test for categoric variables and the Wilcoxon rank-sum test for continuous variables.

RESULTS

The incidence of recurrent angina, reinfarction and heart failure was similar among the three groups. In-hospital mortality, however, was significantly higher in the independent group (13%) than either the simultaneous group (1%, p < 0.001) or the control group (0%, p = 0.002).

CONCLUSIONS

Continuous analysis of ST segment resolution identifies, among patients with AMI with concomitantly occurring ST segment elevation and depression, a subgroup with increased in-hospital mortality. The pathogenic mechanism of increased mortality is not currently known.

A brief self-administered questionnaire to determine functional capacity (the Duke Activity Status Index)

To develop a brief, self-administered questionnaire that accurately measures functional capacity and assesses aspects of quality of life, 50 subjects undergoing exercise testing with measurement of peak oxygen uptake were studied. All subjects were questioned about their ability to perform a variety of common activities by an interviewer blinded to exercise test findings. A 12-item scale (the Duke Activity Status Index) was then developed that correlated well with peak oxygen uptake (Spearman correlation coefficient 0.80). To test this new index, an independent group of 50 subjects completed a self-administered questionnaire to determine functional capacity and underwent exercise testing with measurement of peak oxygen uptake. The Duke Activity Status Index correlated significantly (p less than 0.0001) with peak oxygen uptake (Spearman correlation coefficient 0.58) in this independent sample. The Duke Activity Status Index is a valid measure of functional capacity that can be obtained by self-administered questionnaire.

Ratings of perceived exertion at the lactate threshold in trained and untrained men and women

The purpose of this study was to investigate the effects of state of training and gender on ratings of perceived exertion (RPE) at the lactate threshold (LT), and to determine whether RPE during moderate to heavy sub-maximal exercise is more closely associated with LT or %VO2max. RPE at the LT (RPELT) and at various percentages of VO2max were compared in 10 male and 10 female trained distance runners, and 10 male and 10 female untrained subjects, 18 to 35 yr of age. Mean (+/- SD) VO2max [ml X kg FFW-1 (fat-free weight) X min-1] of the trained men and women (72.3 +/- 1.4 and 73.1 +/- 1.6) was significantly higher (P less than 0.05) than for the untrained men and women (60.2 +/- 1.4 and 53.2 +/- 1.8), confirming their higher cardiorespiratory capacity. Similarly, the mean LTs (%VO2max) of the trained men and women (79.2 +/- 1.7% and 73.3 +/- 1.8%) were significantly higher (P less than 0.05) than for the untrained men and women (66.5 +/- 3.3% and 58.9 +/- 3.3%), and mean values for the men were significantly higher (P less than 0.05) than for the women. The means for RPELT for the four groups, 13.6 +/- 2.1, 13.5 +/- 1.6, 13.5 +/- 1.5, and 12.9 +/- 1.3, respectively, were not significantly different (P greater than 0.05), even though the ratings were given at markedly different levels of VE, VO2 (1 X min-1), heart rate, and %VO2max.(ABSTRACT TRUNCATED AT 250 WORDS)