Flow-mediated dilation is associated with cardiovascular events in non-valvular atrial fibrillation patients.

BACKGROUND: Atrial fibrillation is associated with multiple atherosclerotic risk factors and predisposes to cardiovascular events (CVE). Endothelial dysfunction is associated with atherosclerosis and independently predicts CVE. The aim of the study was to evaluate the association between endothelial dysfunction, as assessed by flow-mediated dilation (FMD), and CVE in AF patients.

METHODS: We prospectively measured FMD in 514 non-valvular AF patients on anticoagulant treatment with vitamin K antagonists. Patients were followed-up for a mean time of 23.5 months. The main composite outcome of the study was the occurrence of stroke/TIA, myocardial infarction, urgent revascularization and cardiovascular death.

RESULTS: Median value of FMD was 4.6% [IQR 1.46-8.00]. A CVE occurred in 44 patients (8.56%):non-fatal myocardial infarction (MI) in 7, fatal MI in 2, stent/coronary artery by-pass graft (CABG) in 10, ischemic non-fatal stroke in 10, fatal stroke in 3, transient ischemic attack (TIA) in 1, and cardiovascular death in 11 patients. Patients who experienced a CVE showed significantly reduced FMD compared to those who did not (3.06% [IQR 0.00-6.00] vs 4.67% [IQR 1.58-8.22], p=0.027). During a mean follow-up of 23.5 months, the rate of CVE was significantly higher in subjects with FMD below median (<4.6%) than in those with FMD above median (27 vs 17, log-rank test p=0.006). COX analysis demonstrated that low FMD (below median) (HR: 2.20, CI 95%:1.13-4.28, p=0.020), age (HR: 1.08, CI 95%: 1.03-1.12, p<0.001), smoking (HR: 4.15, CI 95%: 1.63-10.6, p=0.003) and history of stroke/TIA (HR: 2.38, CI 95%: 1.13-5.04, p=0.023) independently predicted CVE.

CONCLUSIONS: In AF patients low FMD is associated with increased risk of CVE suggesting that impaired artery dilatation predisposes to atherosclerotic complications.