Heart rate recovery – a potential marker of clinical outcomes in heart failure patients receiving beta-blocker therapy

Abstract

Heart rate recovery (HRR) within the first few minutes of graded exercise has been associated with impaired clinical outcomes in patients being evaluated for coronary artery disease. HRR is abnormal in patients with heart failure (HF), but has not been associated with clinical outcomes in these patients. The objective of the present study was to determine whether HRR following cardiopulmonary exercise testing (CPET) correlates with peak oxygen consumption (VO(2)), and whether it impacts clinical outcomes, including HF hospitalizations and total mortality, or the need for cardiac transplantation. CPET was performed in 78 patients referred to the Montreal Heart Institute (Montreal, Quebec) with congestive HF between January 2000 and December 2002. All patients had New York Heart Association class II or III HF with a left ventricular ejection fraction of 45% or lower. Mean (+/- SD) age was 53+/-11 years and left ventricular ejection fraction was 27+/-9%. Forty-four per cent had ischemic cardiomyopathy, 88% received beta-blockers and 79% received angiotensin-converting enzyme inhibitors. HRR was defined as the difference from peak exercise HR to HR measured at specific time intervals. HRR was calculated 30 s, 60 s, 90 s and 120 s after exercise. Mean peak VO(2) was 18.0+/-5.3 mL/kg/min, resting HR was 74+/-13 beats/min and peak HR was 119+/-22 beats/min. HRR measured was 10+/-9 beats/min after 30 s, 20+/-12 beats/min after 60 s, 25+/-15 beats/min after 90 s and 30+/-13 beats/min after 120 s. At 90 s, patients with an HRR below 24 beats/min were more likely to have an HF hospitalization at five-year follow-up (eight hospitalizations [22.2%] versus two hospitalizations [2.7%]; P=0.0134). There was a correlation between peak VO(2) and HRR 90 s and 120 s after completion of the exercise test (r=0.40 after 90 s, P=0.001, and r=0.41 after 120 s, P=0.008). In patients with HF, blunted HRR 90 s and 120 s after CPET correlate with peak VO(2) and are associated with increased risk of worsening HF. HRR is easily measured and a useful marker for morbidity in patients with HF.