Abstract 9925: Association between Resting Heart Rate, Chronotropic Index and Long-term Outcomes in Patients with Heart Failure Receiving Beta-blocker Therapy. Data from the HF-ACTION Trial
Aims: To assess the association between resting heart rate (HR), chronotropic index (CI) and clinical outcomes in patients with chronic heart failure (HF) on optimized β-blocker therapy.
Methods: We performed a sub-study in 1118 patients with chronic HF and reduced ejection fraction (EF <35%) who were enrolled in the HF-ACTION trial. We included patients in sinus rhythm who received a β-blocker and who performed an adequate symptom-limited maximum exercise test. Chronotropic Index was calculated as a percentage of predicted maximum HR reserve achieved, by using the equation (220-age) for estimating maximum HR. A sensitivity analysis using an equation estimating maximum HR for patients with HF taking β-blockers [(119 + (resting HR/2) - (age/2) - (5 * bike)] was also performed. Cox proportional hazards models were fit to assess the association between CI and clinical outcomes.
Results: Median (25th, 75th percentiles) follow-up was 32 (21, 44) months. In a multivariable model including resting HR and CI as continuous variables, neither was associated with the primary outcome of all-cause mortality or hospitalization. However, in multivariable analysis, each 0.1 unit decrease in CI below 0.6 was associated with 17% increased risk of all-cause mortality (Hazard Ratio 1.17, 95% Confidence Interval 1.01-1.36; p=0.036) (figure), and 13% increased risk of cardiovascular mortality or HF hospitalization (Hazard ratio 1.13, 95% Confidence Interval 1.02-1.26; p=0.025). CI did not retain statistical significance when dichotomized at a value ≤0.62 as opposed to analysis of CI as a continuous variable. Sensitivity analysis showed a similar relationship between CI and outcomes.
Conclusion: In patients with chronic HF receiving optimal medical therapy, a decrease in CI below 0.6 was associated with the risk of adverse clinical outcomes. These data support a strategy of including improved heart rate response to exercise, as a therapeutic target in the chronic HF population.
- © 2012 by American Heart Association, Inc.