Insulin resistance is a major determinant of myocardial blood flow impairment in anginal patients.

Abstract

In patients with chest pain, stress-induced myocardial perfusion abnormalities are often the result of depressed myocardial blood flow (MBF) reserve. We investigated the relative contribution of cardiovascular risk factors and coronary atherosclerosis to MBF abnormalities in anginal patients. We studied 167 patients with typical (n = 100) or atypical (n = 67) chest pain who underwent quantitative evaluation of MBF by PET at rest and after dipyridamole infusion, and quantitative coronary angiography (invasive or by 64-slice CT). Patients with left ventricular (LV) dysfunction (ejection fraction <45%) were excluded. Coronary atherosclerosis of ≥50% was defined as obstructive. At rest median MBF was 0.60mlmin-1g-1, and after dipyridamole infusion median MBF was 1.22mlmin-1g-1. MBF reserve was <2 in 77 of 167 patients (46%). Coronary atherosclerosis was present in 67 patients (40%), 26 with obstructive disease. In a univariate analysis several variables were associated with reduced MBF at rest, including male gender, coronary atherosclerosis and elevated LV end-diastolic diameter, and during hyperaemia, including male gender, insulin resistance (IR), smoking habit, LV ejection fraction and end-diastolic diameter. In a multivariate analysis, after adjustment for LV function and for pharmacological treatments, male gender was the only independent predictor of reduced MBF at rest (P < 0.001), while male gender (P = 0.003), IR (P = 0.033) and coronary atherosclerosis (P < 0.001) remained the only independent predictors of reduced hyperaemic MBF. IR (P = 0.043) and coronary atherosclerosis (P = 0.005) were the only predictors of depressed MBF reserve. Coronary atherosclerosis, male gender and IR showed additive effects on hyperaemic MBF. In patients with chest pain and normal LV systolic function, IR, male gender and coronary atherosclerosis are independent and additive determinants of impaired hyperaemic MBF.