Predictors of abnormal heart rate recovery in patients with heart failure reduced and preserved ejection fraction

BACKGROUND: Heart rate recovery (HRR) is becoming an important prognostic maker in heart failure (HF), but very little is known about the underlying mechanisms responsible for its clinical efficacy. Therefore, we examined echocardiographic and exercise (submaximal and maximal) characteristics to gain a better appreciation of HRR and factors responsible for the development of abnormal HRR in patients with both heart failure reduced ejection fraction (HFrEF) and heart failure preserved ejection fraction (HFpEF). METHODS: Cardiopulmonary exercise testing (CPX), a 6-minute walk test (6MWT), and resting 2D echocardiography were randomly performed in 240 HF patients (200 HFrEF, 40 HFpEF) after which HRR was measured. HRR was defined as the difference between heart rate at peak exercise and 1 minute following test termination. RESULTS: Bivariate correlation analyses found significant relationships among most CPX and 6MWT measurements with the highest correlations between 6MWT HRR and 6MWT peak HR (r = 0.65; p < 0.001) and CPX HRR and CPX HRreserve (r = 0.63; p < 0.001). The relationship between 6MWT HRR and CPX HRR was very good (r = 0.91; p < 001). Multivariate logistic regression of submaximal and maximal exercise found 6MWT peak HR and exercise oscillatory ventilation (EOV), respectively, were the strongest predictors (p < 0.001) of abnormal HRR. The E/E' was a significant predictor (p < 0.001) of abnormal HRR, but EOV was the strongest predictor of abnormal HRR (OR = 6.5). CONCLUSIONS: HRR after both CPX and the 6MWT is significantly related to many exercise and echocardiographic measures with the most significant predictors of abnormal HRR being related to indices of cardiorespiratory performance in patients with HFrEF and HFpEF.