Chronotropic Incompetence Among People With HIV Improves With Exercise Training in the Exercise for Healthy Aging Study

Abstract

Background: People with HIV (PWH) have lower exercise capacity than peers without HIV, which may be explained by chronotropic incompetence, the inability to increase heart rate during exercise.

Methods: The Exercise for Healthy Aging Study included adults aged 50 to 75 years 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; chronotropic incompetence <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 years; 7% female), 28% of PWH vs 11% of controls had chronotropic incompetence at baseline (P = .067). AHRR was lower among PWH (91% vs 101%; difference, 10%; 95% CI, 1.9%-18.9%; P = .02). At week 12, AHRR normalized among PWH (+8%; 95% CI, 4%-11%; P < .001) and was sustained at week 24 (+5%; 95% CI, 1%-9%; P = .008) versus no change among controls (95% CI, -4% to 4%; P = .95; interaction P = .004). After 24 weeks of exercise, 15% of PWH and 10% of controls had chronotropic incompetence (P = .70).

Conclusions: Chronotropic incompetence contributes to reduced exercise capacity among PWH and improves with exercise training.

Keywords: HIV; adjusted heart rate reserve/chronotropic index; cardiorespiratory fitness; chronotropic incompetence; exercise training.

Figure 1.

Chronotropy and peak VO₂ by HIV status and exercise training duration. Adjusted heart rate reserve (AHRR; top) and peak VO₂ (bottom) among adults with and without HIV at baseline, after 12 weeks of exercise, and after 24 weeks of exercise. Data are presented as median (line), IQR (box), upper and lower adjacent values, which are 1.5 times the interquartile range further from the first and third quartiles (whiskers), and outliers (circles). Dashed line represents the definition for chronotropic incompetence among people not taking chronotropic medications (AHRR <80%). There is a greater increase in AHRR among people with HIV from baseline to week 12 as compared with people without HIV, which is sustained at week 24. Similarly, from baseline to week 12, there is a greater increase in peak VO₂ among people with HIV vs people without HIV, with a similar trend from week 12 to 24.

Figure 2.

Association between chronotropy and cardiorespiratory fitness. Scatter plots and linear fit of the association between adjusted heart rate reserve (AHRR; x-axis) and peak VO₂ (y-axis) at baseline. Adjusted for age, sex, and body mass index, each 10% increase in AHRR was associated with a 1.4-mL/kg/min higher peak VO₂.