Heart rate and adverse outcomes in patients with atrial fibrillation: A combined AFFIRM and AF-CHF substudy

BACKGROUND An elevated resting heart rate has been associated with adverse cardiovascular outcomes. Its prognostic value has not specifically been examined in patients with atrial fibrillation. OBJECTIVE The purpose of this study was to assess the relationship between resting heart rate measured in sinus rhythm and in atrial fibrillation and subsequent hospitalizations and death. METHODS An analysis of individual patient-level data from subjects enrolled in the AFFIRM and AF-CHF trials was conducted to determine the impact of resting heart rate on hospitalizations and mortality. Separate analyses were performed in atrial fibrillation and sinus rhythm. A total of 7159 baseline ECGs (4848 in atrial fibrillation, 2311 in sinus rhythm) were analyzed in 5164 patients (34.8% female, age 68.2 +/- 8.3 years). RESULTS During mean follow-up of 40.8 +/- 16.3 months, 1016 patients died (668 cardiovascular deaths), and 3150 required at least 1 hospitalization (2215 cardiovascular). An elevated baseline heart rate in sinus rhythm was associated with increased all-cause mortality [hazard ratio (HR) 1.24 per 10 bpm increase, 95% confidence interval (CI) 1.14-1.36, P < .0001]. In contrast, a baseline heart rate in atrial fibrillation was not associated with mortality. However, compared to heart rates 90-114 bpm in atrial fibrillation, a heart rate >114 bpm was independently associated with all-cause (HR 1.18, 95% CI 1.06-1.31, P = .0018) and cardiovascular (HR 1.25, 950/0 CI 1.10-1.42, P = .0005) hospitalizations. CONCLUSION In patients with a history of atrial fibrillation, an elevated baseline heart rate in sinus rhythm is independently associated with mortality. In contrast, the baseline heart rate in atrial fibrillation is not associated with mortality but predicts hospitalizations.