Early detection of abnormal coronary flow reserve in asymptomatic men at high risk for coronary artery disease using positron emission tomography

Abstract

Background: The objective of this study was to compare coronary flow reserve (CFR) as a measure of vascular integrity in asymptomatic middle-aged men with family history of coronary artery disease (CAD) and a high-risk lipid profile with men without risk factors for CAD using positron emission tomography (PET). Previous studies suggested that the assessment of CFR is a sensitive means to detect vascular abnormalities before angiographic appearance of CAD. N-13 ammonia PET scanning allows noninvasive evaluation of regional and global myocardial blood flow and thereby quantification of CFR. Methods and Results: We used dynamic N-13 ammonia PET imaging in conjunction with intravenous adenosine to assess regional and global CFR in asymptomatic middle-aged men with high risk (group 1, n=16) and men without any known risk factors (group 2, n=11) for CAD. Group 1 patients were selected based on positive family history of CAD, one or more lipid abnormalities, and a normal stress test. No patient had history of diabetes or hypertension. A three- compartment tracer kinetic model developed and validated in our institution was used to calculate myocardial blood flow. Absolute myocardial blood flow (mL/100 g per minute) was calculated in five territories for each patient. CFR was defined as the ratio of blood flow during maximum pharmacological vasodilatation to blood flow at rest. Comparisons of CFR between the two groups of patients were performed. The mean age was similar between groups (group 1, 49.3±0.5 years; group 2, 48.1±8.7 years; P=NS). Group 1 had higher total cholesterol (mg/dL) (241±43 versus 173±34, P