Side branch occlusion complicating percutaneous transluminal coronary angioplasty.

A frequent concern during angioplasty is the possibility of occluding important side branches that originate in arterial stenoses subjected to balloon dilatation. The effect of dilatation on 93 side branches (greater than or equal to 1 mm in diameter) was evaluated in 86 patients undergoing percutaneous transluminal coronary angioplasty (PTCA) in whom those branches arose directly in dilated segments of the left anterior descending, circumflex, or right coronary arteries. Seventy-six of the 93 side branches had minor (less than 50%) narrowing at their origin. Among these side branches, nine (12%) were compromised by PTCA. Seventeen of the 93 side branches had greater than 50% ostial stenosis. Significantly more of these side branches (seven of seventeen, or 41%) were compromised by PTCA (P less than .01). Even when compromise does occur, it usually takes the form of increased stenosis rather than total occlusion. The presence of side branches originating in stenotic lesions is not a contraindication to PTCA since serious compromise of such branches rarely results from this procedure.