DIFFERENCE OF REGIONAL CORONARY FLOW RESERVE ASSESSED BY ADENOSINE TL-201 SCINTIGRAPHY EARLY AND 6 MONTHS AFTER SUCCESSFUL PERCUTANEOUS TRANSLUMINAL CORONARY ANGIOPLASTY OR STENT IMPLANTATION

This study assesses regional coronary flow reserve using adenosine tha llium-201 scintigraphy early and 6 months after angiographically succe ssful percutaneous transluminal coronary angioplasty (PTCA) or stent i mplantation. Seventeen consecutive men with a significant isolated lef t anterior descending coronary artery stenosis were scheduled for repe at coronary angiography and adenosine-planar thallium-201 scintigraphy within 24 hours and 6 months after successful PTCA (n = 8) or stent i mplantation (n = 9). After background subtraction, left ventricular se gmental uptake was semiquantitatively assessed on thallium images. The perfusion defect severity was scored from 0 (normal) to 3. Coronary a ngiograms were analyzed using an automated edge contour detection comp uter analysis system. Data are expressed as mean value +/- 1 SD, and p roportions as percentage. The residual narrowing was 17 +/- 8% after P TCA and 9 +/- 2% after stent implantation (p = 0.02). Twenty-four hour s after the procedure, hypoperfused segments were detected in all pati ents (100%) and in 4 patients (44%) (p = 0.05), respectively. The tota l number of hypoperfused segments was greater after PTCA than after st ent implantation (16 [40%] vs 7 [16%], p = 0.001, respectively) as wet s the perfusion defect severity (4.4 +/- 3.1 vs 1 +/- 1.2, p = 0.006). Six months after the procedure, 3 of the 5 patients who had undergone PTCA without restenosis still had reversible perfusion defects. None of the stent-treated patients had restenosis or reversible perfusion d efects (p = 0.05). Among PTCA-treated patients without restenosis, the total number of hypoperfused segments and the perfusion defect severi ty were 9 of 25 (36%) and 0.8 +/- 0.8, respectively. Thus, a regional reduction in coronary flow reserve, occasionally observed early after successful stent implantation, is probably due to a transient alterati on of small coronary vessels, as was also supported by the absence of perfusion defects 6 months after the procedure. The more severe impair ment of regional coronary flow reserve observed early after successful PTCA is probably also due to angiographic underestimation of the resi dual stenosis, as suggested also by the persistence of reversible perf usion defects 6 months after the procedure in a few patients. (C) 1996 by Excerpta Medica, Inc.