Microvascular endothelial dysfunction in heart failure patients: An indication for exercise treatment?

Background: Endothelial dysfunction represents a diagnostic marker to differentiate disease severity in chronic heart failure (CHF) patients. Retinal vessel phenotyping was applied in CHF patients as it has been acknowledged as a sensitive diagnostic tool to quantify microvascular health and overall cardiovascular risk.& nbsp;Methods: The central retinal arteriolar (CRAE) and venular diameter equivalents (CRVE) as well as the retinal microvascular function, quantified by arteriolar (aFID) and venular flicker-light induced dilatation (vFID), were analyzed in 26 CHF patients. These data were compared with 26 age-and sex-matched healthy peers. The effects of an exercise intervention on retinal microvascular health in one CHF patient were investigated to demonstrate potentially beneficial effects of exercise treatment in a case report format as proof of concept.& nbsp;Results: CHF patients showed narrower CRAE (170 +/-& nbsp;16 mu m vs. 176 +/-& nbsp;16 mu m, p = 0.237) and wider CRVE (217 +/-& nbsp;20 mu m vs. 210 +/- 17 mu m, p = 0.152), resulting in a significantly lower arteriolar-to-venular diameter ratio (AVR, 0.79 +/-& nbsp;0.07 vs. 0.84 +/-& nbsp;0.06, p = 0.004) compared to controls. More strikingly, CHF patients showed significantly lower mean aFID (1.24 +/- 1.14% vs. 3.78 +/-& nbsp;1.85%, p < 0.001) and vFID (2.89 +/-& nbsp;1.33% vs. 3.88 +/-& nbsp;1.83%, p = 0.033). Twelve weeks of exercise therapy induced wider CRAE (143 +/-& nbsp;1.0 mu m vs. 153 +/-& nbsp;0.9 mu m), narrower CRVE (183 +/-& nbsp;3.1 mu m vs. 180 +/-& nbsp;2.4 mu m) and improved aFID (0.67% vs. 1.25%) in a male 78 years old CHF patient.& nbsp;Conclusions: aFID is a sensitive diagnostic tool to quantify microvascular impairments in CHF patients. Exercise treatment in CHF patients has high potential to improve retinal microvascular health as a marker for vascular regeneration and overall risk reduction, which warrants further examination by randomized controlled trials.