Chronotropic Incompetence and Risk of Atrial Fibrillation: The Henry Ford ExercIse Testing (FIT) Project

Objectives The goal of this study was examine the association between chronotropic incompetence and incident atrial fibrillation (AF). Background Patients with an inadequate heart rate response during exercise may have abnormalities in sinus node function or autonomic tone that predispose to the development of AF. Methods The association between heart rate response and incident AF was examined in 57,402 patients (mean age 54 ± 13 years, 47% female, 64% white) free of baseline AF who underwent exercise treadmill stress testing from the Henry Ford ExercIse Testing (FIT) Project. Age-predicted maximum heart rate (pMHR) values <85% and chronotropic index values <80% were used to define chronotropic incompetence. Cox regression, adjusting for demographic characteristics, cardiovascular risk factors, medications, coronary heart disease, heart failure, and metabolic equivalent of task achieved, was used to compute hazard ratios (HRs) and 95% confidence intervals (CIs) for the association between chronotropic incompetence and incident AF. Results Over a median follow-up of 5.0 years (25th to 75th percentiles: 2.6 to 7.8 years), a total of 3,395 (5.9%) participants developed AF. pMHR values <85% were associated with an increased risk of developing AF (HR: 1.33; 95% CI: 1.22 to 1.44). Chronotropic index values <80% also were associated with an increased risk of AF (HR: 1.28; 95% CI: 1.19 to 1.38). Using varying cutoff points to define chronotropic incompetence, the associations of pMHR and chronotropic index with AF remained significant. Conclusions Our analysis suggests that patients with inadequate heart rate response during exercise have an increased risk of developing AF.