MYOCARDIAL FLOW RESERVE IN LONG-TERM SURVIVORS OF REPAIR OF ANOMALOUSLEFT CORONARY-ARTERY FROM PULMONARY-ARTERY

Objectives. This study sought to evaluate regional myocardial how rese rve in long-term survivors of repair of anomalous left coronary artery from pulmonary artery (ALCAPA) and to relate the flow abnormalities t o the patients' exercise performance. Background. Patients with ALCAPA usually present during infancy with severe ischemic cardiomyopathy. T he left ventricular function recovers after surgical repair, However, the extent of recovery of myocardial blood how (MBF) and its potential physiologic significance in long-term survivors are unknown. Methods. We evaluated MBF (ml/g per min) at baseline and during maximal corona ry vasodilation by adenosine in 11 patients after ALCAPA repair (media n age 17 years, range 7 to 22) using nitrogen-13 ammonia and dynamic p ositron emission tomographic imaging. Patients also underwent an incre mental exercise test with metabolic monitoring. In each patient, MBP w as quantified in the three major vascular territories: the left anteri or descending and left circumflex coronary artery territories and the right coronary artery (control region) territory. Results. Basal MBF w as mildly reduced in the left coronary territories versus the control region (0.79 +/- 0.14 vs, 0.85 +/- 0.19, p = 0.05), During hyperemia, flow in the left coronary territories was significantly lower than tha t in the control region (2.1 +/- 0.5 vs. 2.6 +/- 0.5, p < 0.001). As a result, myocardial flow reserve was lower in the left coronary territ ories than in the control region (2.6 +/- 0.7 vs. 3.2 +/- 0.7, p < 0.0 01). Exercise performance was impaired in patients when compared with age-matched control subjects, Maximal oxygen consumption correlated li nearly with maximal hyperemic hows in the left coronary artery territo ries (r = 0.73, p = 0.03). Conclusions. Long-term survivors of ALCAPA repair demonstrate regional impairment of myocardial flow reserve. Thi s may contribute to impaired exercise performance by limiting cardiac output reserve. (C) 1998 by the American College of Cardiology.