Impaired flow-mediated dilation and risk of restenosis in patients undergoing coronary stent implantation

Background - Impaired endothelial function is a key event in the atherosclerosis process and predicts future cardiovascular events in subjects with and without coronary artery disease (CAD). We performed the first prospective study evaluating whether early measurement of brachial artery endothelium-dependent dilation (flow-mediated dilation [FMD]) after coronary stenting could predict occurrence of in-stent-restenosis. Methods and Results - The study population included 136 patients with single-vessel CAD undergoing percutaneous coronary intervention (PCI) with stenting and at least 6 months of follow-up. All patients underwent ultrasound detection of brachial artery reactivity 30 days after PCI; FMD was investigated before and after 5 minutes of occlusion of the brachial artery, and nitroglycerin-mediated dilation was investigated before and after administration of sublingual nitrates. Clinical in-stent restenosis was demonstrated in 20 patients (15%), whereas 116 patients (85%) remained free of signs or symptoms of recurrent ischemia. FMD was significantly impaired in patients with restenosis versus those without restenosis (percent diameter variation 4.6±5.8% versus 9.5±6.6%, P=0.002); moreover, 4% of patients with FMD ≥7% (median value) developed in-stent restenosis versus 28% of those with FMD <7% (P=0.0001). On multivariate analysis, FMD was the strongest predictor of restenosis (OR 4.5, 95% CI 2.4 to 12.0); conversely, nitroglycerin-mediated dilation did not independently predict the risk of restenosis (OR 2.4, 95% CI 0.8 to 6.3). Conclusions - This is the first prospective study indicating that impaired FMD independently predicts occurrence of in-stent restenosis in patients undergoing PCI. Early evaluation of endothelial function after stenting may represent a useful screening tool to stratify patients according to future risk of restenosis.