Temporal pattern of ischemic events in relation to dual antiplatelet therapy in patients with unprotected left main coronary artery stenosis undergoing percutaneous coronary intervention.

Objectives: The aim of this study was to investigate whether there is a temporal pattern of ischemic events in relation to dual antiplatelet therapy in patients with unprotected left main coronary artery (ULMCA) stenosis treated with percutaneous coronary intervention (PCI).

Background: Identifying which periods during follow-up of patients with ULMCA stenosis treated with PCI are associated with higher risk of clinical events might help to improve therapeutic strategies.

Methods: We analyzed data from 15 centers involved in an observational study conducted by the Italian Society of Invasive Cardiology on patients with ULMCA stenosis treated with PCI. Eight hundred ninety-four patients were enrolled.

Results: At 30-day follow-up, the rate of cardiac mortality and myocardial infarction (MI) was 5.4%. In patients still taking dual antiplatelet therapy, the adjusted incidence rate ratio/10,000 patient-days of the combination of cardiac mortality and MI in the 31- to 180-day interval compared with the 181- to 360-day interval after PCI was 3.64 (p = 0.035). This risk was particularly high in patients with acute coronary syndromes. After stopping clopidogrel, the adjusted incidence rate ratio of cardiac mortality and MI in the 0- to 90-day interval compared with the 91- to 180-day interval was 4.20 (p = 0.009).

Conclusions: In patients with ULMCA stenosis taking dual antiplatelet therapy there is an increased hazard of cardiac mortality and MI between 31 and 180 days compared with 181 to 360 days. Furthermore, there is an increased hazard of cardiac mortality and MI in the first 90 days after stopping clopidogrel.