[Evaluation of coronary reserve in angina pectoris with angiographically normal coronary arteries].

Coronary reserve was studied: 1) during rapid atrial pacing and then, 2) during dipyridamole infusion (0.6 mg/Kg/4 min) in 3 groups of subjects: 13 patients with angina pectoris and angiographically normal coronary arteries (ANC) with proven myocardial ischaemia during atrial pacing, 15 patients with coronary artery disease (COR) and 17 normal controls with normal coronary angiography and atrial pacing. Coronary sinus flow (QCS) was measured by thermodilution and myocardial metabolism studied by the coefficient of lactate extraction (K). At maximal pacing rates, K remained 15 p. 100 in the control group (average 24 +/- 7 p. 100) but was inversed in the ANC (-3 +/- 10 p. 100) and COR groups (-27 +/- 38 p. 100). The risk in QCS was low in the COR group (+60 +/- 33 p. 100) p less than 0.02, but significant in the ANC group (+104 +/- 57 p. 100) and normal controls (+107 +/- 41 p. 100). Coronary reserve, calculated as the percentage increase in QCS with dipryridamole, was found to be the same in the ANC group (+225 +/- 79 p. 100) as in normal subjects (+191 +/- 81 p. 100) but was low in the COR group (74 +/- 42 p. 100, p less than 0,001). Therefore, no reduction in coronary reserve was shown in patients with angina and normal coronary arteries whilst the myocardial ischaemia in coronary disease does seem to be related to an amputation of the coronary reserve.