Small vessel disease and intracoronary plaque composition: a single centre cross-sectional observational study

Cardiac events are commonly triggered by rupture of intracoronary plaque. Many studies have suggested that retinal small vessel abnormalities predict cardiac events. The present study examined retinal microvascular abnormalities associated with intracoronary plaque. This was a single centre cross-sectional observational study of consecutive subjects who underwent coronary angiography and intracoronary optical coherence tomography (OCT) of occlusive coronary artery disease. Subjects' retinal images were deidentified and graded for microvascular retinopathy (Wong and Mitchell classification), and vessel calibre using a semiautomated method based on Knudtson's modification of the Parr Hubbard formula. Control subjects had no significant plaque on angiography. Analysis used the Fisher's exact test or student t-test. Thirty-two subjects with intracoronary plaque including 22 males (79%) had a mean age of 62.6 ± 9.4 years. Twenty-four (86%) had hypertension, 10 (36%) had diabetes, and 21 (75%) were current or former smokers. Their average mean arterial pressure was 90.5 ± 5.8 mm Hg, and mean eGFR was 74 ± 15/min/1.73 m². On angiography, 23 (82%) had a left anterior descending artery (LAD) stenosis, their mean diseased vessel score was 1.86 ± 1.21, and mean total stent number was 1.04 ± 1.00. Plaque type was mainly (>50%) fibrous (n = 7), lipid (n = 7), calcific (n = 10), or mixed (n = 4). Control subjects had a lower mean diastolic BP (p = 0.01), were less likely to have an LAD stenosis (p < 0.001), a lower mean diseased vessel score (p < 0.001) and fewer stents (p = 0.02). Subjects with plaque were more likely to have a moderate microvascular retinopathy than those with none (p = 0.004). Moderate retinopathy was more common with lipid (p = 0.05) or calcific (p = 0.003) plaque. Individuals with calcific plaque had a larger arteriole calibre (158.4 ± 15.2 µm) than those with no plaque (143.8 ± 10.6 µm, p = 0.02), but calibre was not related to diabetes or smoking. Calibre did not correlate with plaque length, thickness or arc angle. Thus, subjects with intracoronary artery plaque are more likely to have a moderate microvascular retinopathy. Those with calcific plaque have larger retinal arterioles which is consistent with our previous finding of larger vessel calibre in triple coronary artery disease. Retinal microvascular imaging warrants further evaluation in identifying severe coronary artery disease.