Short- and long-term changes in myocardial perfusion after percutaneous transluminal coronary angioplasty assessed by thallium-201 exercise scintigraphy.

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Abstract
Patients [49] in whom percutaneous transluminal coronary angioplasty (PTCA) was attempted were evaluated by Tl-201 myocardial scintigraphy after exercise and at rest before the intervention. After successful PTCA of a single stenosis in a native vessel (30 of 44 patients) and of a stenosis in an aortocoronary bypass graft (3 of 5 patients), scintigraphy was repeated within 3 wk in 30 patients. Long-term follow-up studies by scintigraphy at 5-6 mo. intervals up to more than 2 yr (mean follow-up 18 mo.) were performed in 16 patients. Before PTCA, clear-cut regions of decreased Tl-201 activity were observed in 43 of 49 patients. Tl-201 activity within this zone was reduced to 74 .+-. 1% (SEM [standard error of mean]) of maximal myocardial Tl-201 activity after exercise, but returned to normal (> 80%) at rest (88 .+-. 1%, P < 0.001). After PTCA no distinct defects were recognizable in the region of previously decreased Tl-201 activity. The respective values were 89 .+-. 1% after exercise at identical work loads (P < 0.001 compared with the corresponding values before PTCA) and 94 .+-. 1% (P < 0.01) at rest. These results paralleled the angiographic findings which showed an increase in luminal diameter in the stenotic segment of the treated vessel, from an average of 15 .+-. 2% of the pre- and poststenotic vessel diameter before PTCA to 67 .+-. 3% (P < 0.001) after PTCA. During long-term follow-up, Tl-201 activity remained normal after exercise in the entire heart in 13 of 16 patients. In 3 patients a new defect in the same location as before treatment reappeared 4 1/2, 6 and 29 1/2 mo. after PTCA because the stenosis recurred, as documented by angiography. Tl-201 exercise scintigraphy apparently permits the best documentation of the ongoing changes in myocardial perfusion after PTCA.