Chronotropic Incompetence among People with HIV Improves with Exercise Training in the Exercise for Healthy Aging Study.

Background: People with HIV (PWH) have lower exercise capacity compared to HIV-uninfected peers, which may be explained by chronotropic incompetence (CI), the inability to increase heart rate during exercise. Methods: The Exercise for Healthy Aging Study included adults ages 50-75 with and without HIV. Participants completed 12 weeks of moderate intensity exercise, before randomization to moderate or high intensity for 12 additional weeks. We compared adjusted heart rate reserve (AHRR; CI <80%) on cardiopulmonary exercise testing by HIV serostatus, and change from baseline to 12 and 24 weeks using mixed effects models. Results: Among 32 PWH and 37 controls (median age 56, 7% female, mean BMI 28 kg/m2), 28% of PWH compared to 11% of controls had CI at baseline (p=0.067). AHRR was lower among PWH (91 vs 102%; difference 11%, 95% CI 2.5-19.7; p=0.01). At week 12, AHRR normalized among PWH (+8%, 95% CI 4-11; p<0.001) and was sustained at week 24 (+5, 95%CI 1-9; p=0.008) compared to no change among controls (95%CI -4 to 4; p=0.95; pinteraction=0.004). After 24 weeks of exercise, only 15% PWH and 10% of controls had CI (p=0.70). Conclusions: Chronotropic incompetence contributes to reduced exercise capacity among PWH and improves with exercise training.