Nonculprit Lesion Myocardial Infarction Following Percutaneous Coronary Intervention in Patients With Acute Coronary Syndrome

Background: Recent emphasis on reduced duration and/or intensity of antiplatelet therapy following percutaneous coronary intervention (PCI) irrespective of indication for PCI may fail to account for the substantial risk of subsequent nontarget lesion events in acute coronary syndrome (ACS) patients.

Objectives: The authors sought to examine the effect of more potent antiplatelet therapy on the basis of the timing and etiology of recurrent myocardial infarction (MI) or cardiovascular death following PCI for ACS.

Methods: In the TRITON-TIMI 38 study (Trial to Assess Improvement in Therapeutic Outcomes by Optimizing Platelet Inhibition With Prasugrel-Thrombolysis In Myocardial Infarction 38), which randomized patients to prasugrel or clopidogrel, 12,844 patients with ACS received at least 1 stent. MI and cardiovascular death were categorized as: 1) procedural (related to revascularization); 2) definite or probable stent thrombosis (ST); or 3) spontaneous (non-ST or non-procedure-related). Median follow-up was 14.5 months.

Results: Among the first events occurring within 30 days, 584 (69.0%) were procedural, 126 (14.9%) ST-related, and 136 (16.1%) spontaneous. After 30 days, 22 (4.7%) were procedural, 63 (13.5%) were ST-related, and 383 (81.8%) spontaneous. Prasugrel significantly reduced the incidence of MI or cardiovascular death for ST-related (1.0% vs. 2.1%; p < 0.001) and spontaneous events (3.9% vs. 4.8%; p = 0.012), with a directionally consistent numerical reduction for procedural events (4.4% vs. 5.1%; p = 0.078). Prasugrel increased spontaneous, but not procedural, major bleeding.

Conclusions: Long-term potent antithrombotic therapy reduces de novo (spontaneous) atherothrombotic events in addition to preventing complications associated with stenting of the culprit lesion following ACS. In patients undergoing PCI for ACS, spontaneous events predominate after 30 days, with the later-phase cardiovascular benefit of potent dual antiplatelet therapy driven largely by reducing de novo atherothrombotic ischemic events. (Comparison of Prasugrel [CS-747] and Clopidogrel in Acute Coronary Syndrome Subjects Who Are to Undergo Percutaneous Coronary Intervention; NCT00097591).