Microvascular reactivity in rehabilitating cardiac patients based on measurements of retinal blood vessel diameters

Exercise-based rehabilitation improves general cardiovascular fitness. The impact on the microvascular system has been studied in less detail. We measured changes in retinal blood vessel diameters, as a proxy for microvascular reactivity, in cardiac patients and we assessed the impact of a rehabilitation program on retinal vessel diameters. Cardiac patients (n = 78) and age-matched healthy controls (n = 32) performed an initial maximal endurance cycling test. Patients then participated in a 12-week rehabilitation program with additional endurance tests being performed six and twelve weeks after the initial test. Fundus images were collected immediately before and 0, 5, 10, 15 and 30 min after the endurance test. Widths of retinal blood vessels, represented as Central Retinal Arteriolar/Venular Equivalent (CRAE/CRVE) were calculated from the images. At the start of the rehabilitation program, CRAE and CRVE values of the patients changed immediately after the endurance test with respectively −1.90 μm (95% CI: −3.58; −0.22) and −5.32 μm (95% CI: −7.33; −3.30) compared to baseline values. In contrast, CRAE and CRVE values of healthy controls were respectively increased [3.52 μm (95% CI: 2.34; 4.69)] and decreased [−3.17 μm (95% CI: −5.27; −1.07)]. After six and twelve weeks, CRAE responses of patients immediately after endurance test increased respectively with 5.98 μm (95% CI: 4.25; 7.71) and 4.44 μm (95% CI: 3.18; 5.71). These responses were similar to the microvascular reactions observed in the control group. Arteriolar and venular retinal microvascular responses in cardiac patients were different from the ones of healthy controls. Retinal microvascular response of cardiac patients improved during rehabilitation. •Maximal endurance cycling test induces changes in retinal blood vessel diameters.•Cardiac patients show an impaired response as compared to age-matched healthy controls.•Exercise-based rehabilitation improves retinal blood vessel response in cardiac patients.•Analysis of retinal blood vessel diameters can be used as proxy of microvascular health.