Abstract 3104: Heart Rate Recovery Predicts Major Cardiac Events in Patients with Heart Failure Receiving a Beta-Blocking Agent
Introduction: Heart rate recovery (HRR) following a maximal exercise test has demonstrated prognostic value in several investigations. The analysis of HRR in the heart failure (HF) population is, however, limited, particularly in a cohort receiving a beta-blocking (BB) agent.
Hypothesis: We assessed the hypothesis that HRR would maintain prognostic value in HF patients prescribed a BB agent.
Methods: One hundred and fifty-one subjects with HF (79% male/21% female, 54% ischemic/ 46% non-ischemic, age: 54.3 ± 12.6 years, ejection fraction: 31.2 ± 15.3%), on a stable dose of a BB agent, underwent cardiopulmonary exercise testing to determine peak oxygen consumption (VO2), the minute ventilation/carbon dioxide production (VE/VCO2) slope, peak respiratory exchange ratio (RER), percent-predicted maximal heart rate achieved (PPMHR) and HRR at one minute. Subjects were tracked for major cardiac events following testing.
Results: Mean values for peak VO2, the VE/VCO2 slope, peak RER, PPMHR and HRR were 17.9 ± 6.8 mlO2 ·kg−1·min−1, 33.0 ± 8.7, 1.07 ± 0.14, 75.1 ± 14.9% and 16.4 ± 13.6 beats per minute, respectively. There were 25 major cardiac events (20 deaths, 2 transplants, 3 left ventricular assist device implantations; mean tracking period: 26.7 ± 23.2 months, annual event rate: 6.8%) during the tracking period. A HRR threshold of ≤/> 11 beats per minute was prognostically optimal (hazard ratio: 4.4, 95% confidence interval: 1.8 –10.6, 91.1% vs. 72.1% event free survival, p<0.001). Multivariate Cox regression analysis revealed the VE/VCO2 slope was the strongest predictor of cardiac events (Chi-square: 13.7, p<0.001) while HRR added significant value and was retained (residual chi-square: 4.6, p = 0.03). Peak VO2 did not add prognostic value and was removed from the regression (residual chi-square: 0.97, p = 0.33).
Conclusions: In conclusion, these results indicate HRR maintains prognostic value in HF patients prescribed a BB agent. Furthermore, HRR added predictive value to the VE/VCO2 slope, perhaps one of the strongest prognostic markers obtained from cardiopulmonary exercise testing. The clinical assessment of HRR may therefore be warranted in HF patients who are prescribed a BB agent.