Morphological changes after percutaneous transluminal coronary angioplasty of unstable plaques. Insights from serial angioscopic follow-up.

OBJECTIVE To describe the morphological changes occurring in the months following percutaneous transluminal coronary angioplasty (PTCA) of unstable plaques. BACKGROUND Coronary angioscopy is a relatively new technique to assess plaque morphology. Previous angioscopic studies have shown that unstable coronary lesions are characterized by complex morphology, evidence of plaque rupture, and intraluminal thrombi. No serial angioscopic studies have investigated the effects of PTCA on plaque morphology at such lesions. METHODS We studied 15 patients who underwent successful PTCA for an unstable coronary syndrome (unstable angina: n = 5; recent myocardial infarction: n = 10). Angioscopy was performed immediately before PTCA in 14 patients, immediately after PTCA in 13 patients, and at follow-up (225 +/- 62 days after PTCA) in all patients. RESULTS Pre-PTCA, plaque morphology was defined as complex in 18%, ulcerated in 27%; the vessel was totally occluded in 18% of cases. Plaque colour was yellow in 75% of patients. A thrombus was identified at the lesion site in 71% of patients. Immediately post-PTCA, small surface disruptions and dissections were observed in 62% of patients. Plaque colour was yellow in 85% of cases. Seventy-seven percent of patients had an angioscopically visible thrombus at the PTCA site. At follow-up, however, plaque shape was almost uniformly classified as smooth concentric (93%); plaque colour was white in 93%; no thrombus was observed. CONCLUSIONS These results demonstrate the healing of unstable plaques in the months following PTCA. The angioscopic appearance at 6 months is that of a stable plaque (smooth concentric, white, without thrombus). Whether this stable angioscopic appearance predicts long-term clinical stability remains to be determined.