Cardiac Resynchronization for Class IV Heart Failure
Abstract & Commentary
By Michael H. Crawford, MD
Source: van Bommel RJ, et al. Effect of cardiac resynchronization therapy in patients with New York heart association functional class IV heart failure. Am J Cardiol. ;106:1146-1151.
Although cardiac resynchronization therapy (CRT) is a class-I indication for the treatment of NYHA class III-IV patients with heart failure, few class-IV patients have been treated in the reported trials. Therefore, these investigators from the Netherlands studied 61 such patients to assess the effects of CRT on left ventricular (LV) volumes, symptoms, and long-term outcome. CRT indications included LV ejection fraction (EF) of 35% and an ECG QRS width of > 120 ms. Echocardiography was performed before and 6 months following CRT.
Results: At 6 months, 15% of the patients had died and 3% were readmitted for heart failure, but 64% improved and 18% were unchanged. On echo, a significant decrease in end-systolic volume was observed (167 to 147 mL, p = 0.009), as well as an increase in LVEF (22 to 28% p < 0.001). During a mean long-term follow-up of 30 months on average, 23% of the patients were admitted for heart failure. Eventually, a total of 59% died, most from worsening heart failure (75%). Survivors generally had better composite clinical scores. Baseline estimated glomerular filtration rate was the only baseline characteristic that was independently associated with all-cause mortality. One- and two-year mortality rates after CRT were 25% and 38%, respectively. The authors concluded that CRT improves LV function in patients with class-IV heart failure, but mortality remains high.
The mortality rate in this study is similar to those observed in other studies of class-IV patients treated medically. Thus, one cannot conclude that CRT prolongs life in class-IV patients. However, at 6 months, 64% of the survivors had improved clinically. Also, mean LVEF increased, which may have been part of the reason symptoms declined. So, CRT in class-IV patients does seem to make them feel better.
It is not surprising that most of the CRT patients died of worsening heart failure since many also received defibrillators, which would be expected to markedly reduce or eliminate arrhythmic sudden deaths. It also is not surprising that reduced renal function was the only multivariate predictor of death. Renal function is a marker for mortality in many clinical situations. In heart failure, it suggests worse heart failure associated with reduced organ flow and elevated venous pressure in the kidney. So, it may just be a marker for heart failure so severe or progressive that CRT is only a temporizing measure.
At this time, it appears that for appropriate class-IV heart-failure patients, CRT may reduce symptoms, increase activity, and prevent sudden death (with an ICD), but not affect the high rate of heart failure death.