Imaging Intramyocardial Microcirculatory Function Using Fast Computed Tomography

Abstract

Coronary arterial disease is currently diagnosed and treated primarily on the basis of its impact on the large-diameter epicardial arteries. A structural change, usually a localized narrowing (stenosis) of a coronary artery lumen, is generally detected and quantitated by selective coronary angiography. However, by the time the epicardial artery stenosis results in reduced epicardial flow and the patient becomes symptomatic, it is generally too late to arrest (much less reverse) the disease process in that artery. Therefore, a noninvasive test that identifies presymptomatic, subclinical disease should result in initiation of therapy at a time when the disease process is still reversible. Causal risk factors—i.e., dyslipidemia, arterial hypertension, diabetes mellitus, and smoking—are responsible for the majority of coronary artery disease cases, and risk-factor modification in high-risk asymptomatic individuals has been shown to improve outcome (1). Early risk stratification, aggressive preventive counseling, and therapy in high-risk subjects is therefore recommended (2,3). However, limited economic resourses warrant careful patient selection and appropriate therapeutic aggressiveness. Hence, any imaging tool for this purpose is required (1) to allow identification and quantification of early disease, and (2) to be sensitive enough to ascertain therapeutic efficacy over time to justify continuation or modification of the initiated therapy.