Impaired Coronary Autoregulation Is Associated With Long-term Fatal Events in Patients With Stable Coronary Artery Disease

Abstract

Background: Abnormalities in the coronary microcirculation are increasingly recognized as an elementary component of ischemic heart disease, which can be accurately assessed by coronary flow velocity reserve in reference vessels (refCFVR). We studied the prognostic value of refCFVR for long-term mortality in patients with stable coronary artery disease.

Methods and results: We included patients with stable coronary artery disease who underwent intracoronary physiological evaluation of ≥ 1 coronary lesion of intermediate severity between April 1997 and September 2006. RefCFVR was assessed if a coronary artery with <30% irregularities was present. RefCFVR >2.7 was considered normal. Patients underwent revascularization of all ischemia-causing lesions. Long-term follow-up was performed to document the occurrence of (cardiac) mortality. RefCFVR was determined in 178 patients. Kaplan-Meier estimates of 12-year all-cause mortality were 16.7% when refCFVR >2.7 and 39.6% when refCFVR ≤ 2.7 (P<0.001), whereas Kaplan-Meier estimates for cardiac mortality were 7.7% when refCFVR >2.7 and 31.6% when refCFVR ≤ 2.7 (P<0.001). After multivariable adjustment, refCFVR ≤ 2.7 was associated with a 2.24-fold increase in all-cause mortality hazard (hazard ratio, 2.24; 95% confidence interval, 1.13-4.44; P=0.020) and a 3.32-fold increase in cardiac mortality hazard (hazard ratio, 3.32; 95% confidence interval, 1.27-8.67; P=0.014). Impairment of refCFVR originated from significantly higher baseline flow velocity in the presence of significantly lower reference vessel baseline microvascular resistance (P<0.001), indicating impaired coronary autoregulation as its cause.

Conclusions: In patients with stable coronary artery disease, impaired refCFVR, resulting from increased baseline flow velocity indicating impaired coronary autoregulation, is associated with a significant increase in fatal events at long-term follow-up.

Keywords: coronary autoregulation; coronary flow velocity reserve; reference vessel.