An attenuated heart rate recovery (HRR) immediately after exercise has been shown to be predictive of mortality. It is not known whether HRR predicts mortality when measured in patients with heart failure. The present study was undertaken to evaluate the ability of HRR to predict mortality in patients with heart failure.
We studied 84 NYHA class II or III chronic congestive heart failure patients who had a left ventricular ejection fraction ≤ 40%. All patients underwent symptom limited cardiopulmonary exercise testing. The value for the HRR was defined as the difference in heart rate between peak exercise and one-minute later; a value ≤ 18 beats per minute was considered abnormal. The patients were divided into 2 groups according to the value of HRR. Those with abnormal HRR were assigned to group I and those with normal HRR were assigned to group II. The 2 groups were compared with each other regarding baseline characteristics and exercise capacity assessed by peak VO2.
There were 26 patients (31%) in group I and 58 patients (69%) in group II. Group II patients had better performance on treadmill exercise testing than group I patients. They had greater exercise duration (7.5 ± 3.8 minutes versus 5 ± 3.5 minutes, P = 0.006), better heart-rate reserve (79 ± 25% versus 63 ± 27%, P = 0.01), and higher values of maximal heart-rate (141 ± 18 beats/min versus 132 ± 17 beats/min, P = 0.04). Group II patients also had higher peak VO2 values (16.8 ± 4.4 mL/kg/min versus 14.4 ± 3.6 mL/kg/min, P = 0.01). When we separated the groups according to beta-blocker usage, beta-blockers had no prominent effect on HRR.
In the follow-up period (mean 14.1 ± 6.1 months), the presence of abnormal HRR and lower peak VO2 (≤ 14 mL/kg/min) were the only significant predictors of mortality in our patient population (adjusted hazard ratio [HR] 5.2, 95% CI, 1.3 to 24, P = 0.03 and adjusted HR 13, 95% CI, 2.1 to 25.6, P = 0.005, respectively).
It seems that the attenuated HRR value one minute after peak exercise appears to be a reliable index of the severity of exercise intolerance in heart failure patients and this study supports the value of HRR as a prognostic marker among heart failure patients referred for cardiopulmonary exercise testing for prediction of prognosis.
2006 by the International Heart Journal Association