Impact of a 24- rather than 6-month dual antiplatelet therapy with clopidogrel in patients with left main or proximal left anterior descending coronary artery disease. A post hoc analysis from the (Prolonging Dual Antiplatelet Treatment After Grading Stent ­Induced Intimal Hyperplasia) PRODIGY trial

Aims: This sub-study sought to investigate the effect of a randomised long (24 months) or short (6 months) dual antiplatelet therapy duration in patients with angiographic evidence of lumen narrowing in the left main coronary artery and/or the proximal left anterior descending artery in the setting of the Prolonging Dual Antiplatelet Treatment After Grading Stent-Induced Intimal Hyperplasia (PRODIGY) trial. Methods and results: We stratified the PRODIGY patient population based on the presence of at least one coronary stenosis of more than 30% at visual estimation in the left main coronary artery or proximal left anterior descending artery at the time of the index coronary intervention. This information was prospectively collected during the course of the study. A total of 953 (54.3%) patients underwent treatment or showed lumen narrowing at angiography in the left main coronary artery or proximal anterior descending, whereas 801 (45.7%) were free of disease in these segments. Long-term dual antiplatelet therapy was associated with a 50% decrease of definite/probable/possible stent thrombosis among patients with angiographic disease in the left main or proximal left anterior descending artery (3.2% vs. 5.9%; HR 0.49, 95% CI: 0.23­ 0.88, P=0.03) but also to a 2­fold increase in patients without these angiographic features (4.4% vs. 2.8%; HR 2.08: 95% CI 1.01­4.58, P=0.05), with a highly significant interaction effect (PInt=0.005). In addition, we observed a trend towards qualitative interaction between the high-risk group and the duration of antiplatelet treatment with respect to the occurrence of death for cardiovascular causes or myocardial infarction (PInt=0.09) and for the occurrence of definite stent thrombosis (PInt=0.05) at 24 months, suggesting a possible benefit from a 24-month dual antiplatelet therapy in this patients subset. However, when patients with in-stent restenosis at presentation were excluded from the analysis, no statistically significant interaction was observed for the occurrence of cardiovascular death or myocardial infarction (PInt: 0.10) and definite stent thrombosis (PInt: 0.15), whereas the interaction effect for the occurrence of definite/probable/possible stent thrombosis was still valid (PInt: 0.007). Conclusions: This analysis suggests a possible treatment benefit from a 24-month dual antiplatelet therapy as compared to a 6-month therapy duration after coronary stent implantation in patients with evidence of atherosclerotic disease determining lumen narrowing of the left main coronary artery and/or proximal left anterior descending artery.