High-risk features in non-culprit lesions and clinical outcome after NSTEMI versus STEMI.

Aims: Complete non-culprit (NC) revascularization may help reduce recurrent events after NSTEMI, especially if NC lesions would harbor high-risk plaque features similar to STEMI. The study aimed to assess differences in fractional flow reserve (FFR)-negative NC plaque morphology in patients presenting with NSTEMI versus STEMI and assess the association of high-risk plaque morphology and clinical outcome.

Methods and results: In the prospective PECTUS-obs study, 438 patients presenting with myocardial infarction (MI) underwent optical coherence tomography (OCT) of all FFR-negative intermediate NC lesions. The primary endpoint was the occurrence of major adverse cardiovascular events (MACE, all-cause mortality, non-fatal MI or unplanned revascularization) at two-year follow-up. Four hundred and twenty patients had at least one analyzable OCT, including 203 (48.3%) with NSTEMI and 217 (51.7%) with STEMI. The prevalence of high-risk plaques (HRP), including thin-cap fibroatheromas (TCFA), plaque rupture and thrombus, was comparable between groups. MACE occurred in 29 (14.3%) NSTEMI patients and 16 (7.4%) STEMI patients (Punivariable=0.025 and Pmultivariable=0.270). Incidence of MACE was numerically higher among patients with HRP, irrespective of the clinical presentation at index (Pinteraction=0.684). Among high-risk plaque criteria, plaque rupture was associated with MACE in both NSTEMI (p<0.001) and STEMI (p=0.020).

Conclusion: Presence of NC HRP is comparable between NSTEMI and STEMI and leads to numerically higher event rates in both. These results call for additional research on complete revascularization in NSTEMI and treatment of HRP.