Aim: The usefulness of drugs to treat plaque regression is assessed by intravascular ultrasound (IVUS); however, the impact of plaque regression on clinical outcomes in patients with acute coronary syndrome (ACS) has not been established; therefore, we investigated the relationship between coronary plaque regression and long-term clinical outcomes.
Methods: We analyzed data from 86 patients who underwent percutaneous coronary intervention (PCI) and who were assessed in detail at baseline and at 6 months of follow-up by measuring proximal non-culprit sites of PCI lesions using volumetric IVUS. Patients were divided according to changes in plaque volume over 6 months into one group with plaque regression (n =55; 64.0%) and another with progression (n =31; 36.0%). They were followed up observationally for a mean of 1,736 days.
Results: Baseline characteristics at the time of ACS were similar between the groups. The probability of event-free survival was significantly higher in the regression group than in the progression group as estimated by the Kaplan-Meier method (Log-rank test, p =0.032). Furthermore, the Cox hazards model revealed the relative contribution of plaque regression as a predictor of cardiovascular events (hazard ratio: 0.26; 95% CI, 0.07 to 0.83; p =0.023).
Conclusions: Plaque regression determined by volumetric IVUS over a period of 6 months was associated with a lower rate of cardiovascular events among patients with ACS. This study also demonstrated that plaque regression could be a surrogate marker of future cardiovascular events.