Temporal Sequenze and spatial distribution of ischemic changes during dipyridamole stress test - the key role of microvascular disfunction

Background: It is accepted that, in patients with epicardial coronary atherosclerosis, ischaemia produces a time sequence of events in myocardial regions supplied by stenotic branches characterised by regional wall motion abnormalities (WMA) followed by electrocardiographic changes and angina. Yet, the evidence indicates that patients with coronary atherosclerosis present a diffuse impairment of distal coronary vessels even in remote myocardial regions supplied by non-stenotic branches. Thus, temporal sequence of ischaemic events and the distribution of WMA may be influenced by microcirculatory dysfunction. Methods and Results: The study population consisted of 21 patients with stable angina and isolated stenosis of left anterior descending coronary artery (LAD). Patients underwent electrocardiographic and echocardiographic monitoring during dipyridamole infusion (DIP). During DIP, 14 patients exhibited both echocardiographic abnormalities and electrocardiographic changes and/or angina. In 8 patients (57 %) echocardiographic abnormalities represented the first ischaemic event; in the remaining 6 patients (43 %) the first ischaemic event was represented by electrocardiographic changes and/or angina. WMA appeared in LAD-dependent territories in 4 of 15 patients (27 %), in non-LAD-dependent territories in 5 patients (33 %), in both LAD and non-LAD-dependent territories in the 6 remaining patients (40 %). The mean percentage of abnormal segments and the mean WMA score were similar among the 3 groups (p = 0.8 and p = 0.47). Conclusions: In patients with stable angina, the mechanisms of myocardial ischaemia are determined by a complex interplay between epicardial obstructions and microvascular dysfunction. This evidence underscores the need in individual patients of a tailored treatment based on the main mechanisms of myocardial ischaemia.