If symptom quantification is difficult, quality of life evaluation is even more so. To assess the symptomatic impact of carvedilol in heart failure, all the relevant studies used standardized quality of life measures such as New York Heart Association (NYHA) functional class status, specific activity scales, or Minnesota Living with Heart Failure Questionnaire scores. In the pilot studies, these measures provided some statistically significant evidence of symptomatic relief in moderate-to-severe heart failure treated with carvedilol.
However, improvement was not consistent across all the different types of evaluation performed in two large-scale clinical trials. In the US trial, statistically significant improvement in NYHA class and Minnesota Living with Heart Failure Questionnaire scores was observed in mild and moderate-severe heart failure, but not in severe and dose-dependent heart failure. The Australia-New Zealand (ANZ) trial even showed a minor trend towards worsening symptoms at 6-months follow-up not seen at 12- or 18-month follow-up. Conversely, in the US carvedilol trial, use of a 7-point symptom-based subjective scale mimicking the clinical interaction between physician and heart failure patient showed significant and consistent improvement in symptomatic status on carvedilol, despite no change in the objective measures of functional capacity. The lower risk of hospitalization for heart failure in the US and ANZ trials also reflected symptomatic benefit. Analysis of the changes in NYHA class or symptom scores in terms of the percentage of patients experiencing deterioration revealed less deterioration in those randomized to carvedilol.
The Metoprolol in Dilated Cardiomyopathy (MDC) trial showed improved NYHA class, improved subjective assessment of quality of life, and fewer hospitalizations on metoprolol. The Metoprolol CR/XL Randomized Intervention Trial in Heart Failure (MERIT-HF) confirmed these results.
Initial studies with bucindolol showed significant improvement in NYHA class, but this was not confirmed by the larger Beta-Blocker Evaluation Survival Trial (BEST).
ft-blocker; quality of life; carvedilol; NYHA classification; symptomatic effect