The healing process of infarct-related plaques: Insights from 18 months of serial angioscopic follow-up

Objectives To clarify the healing process of disrupted culprit plaques of acute myocardial infarction (MI), we serially observed the culprit plaques for 18 months after the onset of acute MI by angioscopy. Background Although it has been reported that disruption of the yellow plaque and subsequent thrombosis cause acute MI and that the thrombogenicity of the plaque lasts for a month, the healing process of the plaque after disruption has not been clarified. Methods Eighty-five patients with acute MI were prospectively and consecutively enrolled. Angioscopic studies were performed immediately and at 1, 6 and 18 months after successful reperfusion. The prevalence of yellow plaques and thrombus was examined. The color grade of the plaque was determined as 0 (white), 1 (light yellow), 2 (yellow) or 3 (bright yellow). Results Although yellow plaque was present at the culprit lesion in most patients throughout follow-up, its color grade was reduced from one to six months (1.9 ± 0.6 vs. 1.1 ± 0.7, P = 0.0003) after reperfusion, especially in the patients without hyperlipidemia (HL). The incidence of thrombus was 92.5% immediately after reperfusion, which was reduced significantly to 63.8%, 4.8% and 11.8% at 1, 6 and 18 months, respectively. The incidence of thrombus (77.8% vs. 45.0%, P = 0.03) at one month was higher in the patients with diabetes mellitus (DM). Conclusions The healing process of yellow plaques at the culprit lesions of MI was detected by angioscopy as reductions of color grade and thrombogenicity at six months and partially at one month after the onset of acute MI. This healing process appears to deteriorate by complicating cases of DM or HL.