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

Objectives: To examine the association between chronotropic incompetence and incident atrial fibrillation (AF).

Background: Patients with inadequate heart rate response during exercise may have abnormalities in sinus node function or autonomic tone that predispose to the development of AF.

Methods: We examined the association between heart rate response and incident AF in 57,402 (mean age=54±13 years, 47% female, 64% white) patients 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 demographics, cardiovascular risk factors, medications, coronary heart disease, heart failure, and metabolic equivalent of task achieved, was used to compute hazard ratios (HR) and 95% confidence intervals (CI) for the association between chronotropic incompetence and incident AF.

Results: Over a median follow-up of 5.0 years (25^th-75^th percentiles=2.6, 7.8), a total of 3,395 (5.9%) participants developed AF. pMHR values <85% were associated with an increased risk for AF development (HR=1.33, 95%CI=1.22, 1.44). Chronotropic index values <80% also were associated with an increased risk of AF (HR=1.28, 95%CI=1.19, 1.38). The associations of pMHR and chronotropic index with AF remained significant with varying cut-off points to define chronotropic incompetence.

Conclusions: Our analysis suggests that patients with inadequate heart rate response during exercise have an increased risk for developing AF.