The Impact of Cardiac Rehabilitation on Cardiovascular function Outcomes: Potential Role of Racial Disparities

Abstract

Background: Cardiovascular disease (CVD) is a leading cause of death globally. Cardiac rehabilitation (CR) is an effective treatment for CVD. Minority groups, especially African Americans (AAs), are more vulnerable to CVD. However, the impact of CR on cardiac and vascular function outcomes and the influence of race are not yet clear.

Aims: To investigate (1) the impact of CR on cardiac and vascular function, (2) the role of race in influencing improvements in cardiac and vascular function, and (3) the role of cardiac and vascular functions in predicting exercise capacity using the six-minute walk test (6MWT). Methods: We recruited 17 participants (non-AA n = 9, AA n = 8) and measured cardiac and vascular outcomes at baseline, week 4, and post-CR. Cardiac systolic functions (stroke volume [SV], cardiac output [CO], ejection fraction [EF]) and diastolic function (E/A ratio) were assessed. Vascular function was evaluated using brachial artery flow-mediated dilation (FMD) and carotid-femoral pulse wave velocity (cf-PWV). Regression analysis was utilized to predict 6MWT from cardiovascular outcomes.

Results: CR improved cardiac systolic function, with SV increasing from 79.90±6.41 at baseline to 88.66±5.11 post-CR (p = 0.05), CO from 5.120±0.30 to 5.891±0.29 (p = 0.03), and EF from 40.50±1.93 to 44.30±1.67 (p = 0.01). Diastolic function (Mitral E/A) showed no significant change, but AA participants consistently had lower Mitral E/A ratios compared to non-AA participants at baseline (0.961±0.014 vs. 1.030±0.014, p = 0.002), week 4 (0.976±0.016 vs. 1.046±0.015, p = 0.004), and post-CR (0.957±0.018 vs. 1.034±0.015, p = 0.005). CR significantly improved brachial artery FMD from 2.933±0.32 to 3.969±0.28 (p = 0.02) but had no significant effect on cf-PWV (baseline: 11.716±0.59; post-CR: 10.921±0.53, p = 0.33). AA participants had consistently higher central systolic blood pressure (cSBP) and cf-PWV at all time points. Regression analysis indicated that cardiac diastolic function (Mitral E/A ratio) and arterial stiffness (cf-PWV) were significant predictors of 6MWT (R² = 0.30, p = 0.003).

Conclusion: CR significantly improved cardiac systolic function and peripheral vascular function (brachial artery FMD), but had limited impact on diastolic function and central vascular function (cf-PWV). Diastolic function and arterial stiffness significantly predicted 6MWT performance. Racial differences in response to CR were evident, with AA participants showing lower improvements compared to non-AA participants.