Endothelial function and baroreflex sensitivity according to the oral glucose tolerance test in patients with coronary artery disease and normal fasting glucose levels

Abstract

Endothelial dysfunction and reduced BRS (baroreflex sensitivity) may be present in patients with CAD (coronary artery disease). The normal fasting glucose level does not exclude abnormal glucose metabolism in patients with CAD. The aim of present study was to evaluate endothelial function and BRS according to glucose metabolism in patients with normal fasting plasma glucose and stable CAD subjected to PTCA (percutaneous transluminal coronary angioplasty). Forty-six consecutive patients who underwent elective PTCA were studied (37 men; mean age 56 years). Endothelial function was assessed non-invasively using the arterial vasodilator response to salbutamol (albuterol). BRS was measured using a cross-correlation method. The extent of coronary narrowing was estimated by calculation of the Gensini score. All patients underwent a 75 g OGTT (oral glucose tolerance test). IGT (impaired glucose tolerance) or diabetes was present in approx. 60% of patients. The vasodilator response to salbutamol, as a measure of endothelial dysfunction, was significantly impaired in patients with IGT or diabetes compared with those with normal glucose tolerance (-0.5+/-1.6% compared with -7.9+/-2.2; P=0.01). Glucose metabolism and age were significant predictors of endothelial dysfunction (R(2)=35.2%, P=0.02). BRS did not differ significantly between patients with normal glucose tolerance and those with IGT or diabetes (6.9+/-1.2 compared with 6.1+/-0.6 ms/mmHg respectively; P=0.669). BRS was negatively correlated with age (r=-0.34, P=0.021) and the Gensini score (r=-0.34, P=0.022). The significant predictors of BRS were Gensini score, age and past myocardial infarction (R(2)=37.02%, P=0.002). Patients with established CAD, normal fasting glucose and IGT or diabetes demonstrated impaired endothelial function which did not correlate with the extent of coronary artery involvement. Conversely, BRS in the study population was not affected by glucose metabolism, but showed an interaction with the extent of coronary narrowing.