Determinants of arrhythmic death due to coronary spasm: effect of preexisting coronary artery stenosis on the incidence of reperfusion arrhythmia.

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Abstract
Coronary spasm can occur in the presence or absence of coronary artery disease. We therefore determined the effect of preexisting coronary stenosis on the incidence of ventricular fibrillation during reperfusion after circumflex artery (CFX) occlusion. Twenty dogs underwent a 30-minute open-chest CFX occlusion. During reperfusion, CFX blood flow was restricted by a partial occluder. In dogs that survived reperfusion, peak CFX flow was 91 +/- 44% of baseline (mean +/- SD) compared with 163 +/- 68% in dogs that died of ventricular fibrillation (p less than 0.02). In another 17 dogs, the left anterior descending coronary artery was gradually occluded by an ameroid constrictor. After 17-39 days, the CFX was acutely occluded for 30 minutes and then reperfused. Collateral flow to the CFX, measured by microspheres, was 27.6 +/- 28.3 ml/min . 100 g-1 in dogs that died of reperfusion ventricular fibrillation, compared with 64.4 +/- 27.2 ml/min . 100 g-1 in surviving dogs (p less than 0.02). Thus, the risk of reperfusion ventricular fibrillation is greater in dogs with normal coronary arteries than in dogs with a flow-limiting partial stenosis of the artery undergoing transient occlusion, or chronic stenosis of a second coronary artery inducing collateralization to the artery subsequently undergoing transient occlusion. These results suggest that the risk of ventricular fibrillation during release of coronary spasm may be greater in patients without than in those with coronary artery disease.