AIMS - Endothelial dysfunction is a precursor to the development of symptomatic atherosclerosis. Retinal microvascular reactivity to flicker light stimulation is a marker of endothelial function and can be quantified in vivo. We sought to determine whether retinal microvascular endothelial dysfunction predicts long-term major adverse cardiovascular events (MACE).

METHODS AND RESULTS - In a single center prospective observational study, patients with coronary artery disease (CAD) or cardiovascular risk factors underwent dynamic retinal vessel assessment in response to flicker light stimulation and were followed up for MACE. Retinal microvascular endothelial dysfunction was quantified by measuring maximum flicker light-induced retinal arteriolar (FI-RAD) and venular dilatation (FI-RVD). In total, 252 patients underwent dynamic retinal vessel assessment and 242 (96%) had long-term follow-up. Of the 242 patients, 88 (36%) developed MACE over a median period of 8.6 years (IQR 6.0-9.1). After adjustment for traditional risk factors, patients within the lowest quintile of FI-RAD had the highest risk of MACE (OR 5.21; 95% CI 1.78, 15.28). Patients with lower FI-RAD were also more likely to die (OR 2.09; 95% CI 1.00, 4.40, per standard deviation decrease in FI-RAD). In Kaplan-Meier analysis, patients with FI-RAD responses below the cohort median of 1.4% exhibited reduced MACE-free survival (55.5 vs. 71.5%; log-rank p = 0.004). FI-RVD was not predictive of MACE.

CONCLUSIONS - Retinal arteriolar endothelial dysfunction is an independent predictor of MACE in patients with CAD or cardiovascular risk factors. Dynamic retinal vessel analysis may provide added benefit to traditional risk factors in stratifying patients at risk for cardiovascular events.

TRANSLATIONAL PERSPECTIVE - Subclinical endothelial dysfunction precedes cardiovascular diseases and can be assessed non-invasively using the retinal microvascular network. Retinal arteriolar endothelial dysfunction is an independent predictor of MACE and all-cause mortality in patients with established coronary artery disease or cardiovascular risk factors. Validation studies and investigation into the lifestyle and pharmacological modifiability of endothelial dysfunction could enhance risk prediction and guide intensification of therapy.