Inverse correlation between coronary and retinal blood flows in patients with normal coronary arteries and slow coronary blood flow

Background: The "Slow Coronary Flow" (SCF) phenomenon in the presence of angiographically normal coronaries is attributed to microvascular and endothelial dysfunction. The microcirculation can be non-invasively assessed by measuring retinal blood flow velocity. The aim of the present study was to evaluate the efficacy of the "Retinal Functional Imager" (RFI) device as a noninvasive method of diagnosing patients with slow coronary flow. Methods: Coronary blood flow velocity assessed by corrected TIMI Frame Count and retinal arterioles blood flow assessed by RFI were measured in 28 consecutive patients with normal coronary arteries. The patients were divided into 2 groups: a slow coronary flow (SCF) and a normal coronary flow (NCF) groups. Results: Inverse correlation was found between retinal and coronary blood flows so that higher retinal arterial flow velocity was observed in the SCF group (3.8 +/- 1.1 mm/s vs. 2.9 +/- 0.61 mm/s, respectively, p = 0.022). RFI provided 73% sensitivity and 77% specificity for diagnosing SCF using ROC analysis. Additionally, patients with SCF had higher values of serum LDL cholesterol (104.7 +/- 18.93 mg/dl vs. 81.55 +/- 14.62 mg/dl in NCF, p = 0.005), Glucose (96.9 +/- 23.0 mg/dl vs. 83.55 +/- 9.7 mg/dl in NCF, p = 0.024), and lower percentage of statin consumption (40.0% vs. 76.9% in NCF, p = 0.049). Conclusions: Slow coronary blood flow can be non-invasively diagnosed with Retinal Functional Imager. Patients with normal coronary arteries and slow coronary blood flow have high retinal arteriolar blood flow. Early non-invasive diagnosis of SCF might help detect individuals who are at higher risk to develop coronary atherosclerosis, and to provide them with early preventive measures. (C) 2013 Elsevier Ireland Ltd. All rights reserved.