Original Title: Benefits and Risks of Extended Dual Antiplatelet Therapy after Everolimus-Eluting Stents. For the Dual Antiplatelet Therapy (DAPT) Study Investigators. Reference: James B. Hermiller et al. JACC: Cardiovascular Interventions 2015, online before print.
The DAPT study had shown that continued aspirin plus thienopyridine beyond a year reduces ischemic events. Given the fairly low rate of thrombosis and acute myocardial infarction (AMI) with the current drug eluting stents (DES), this DAPT sub-study specifically examined outcomes of patients treated with everolimus eluting stents (EES).
The DAPT trial had enrolled 25682 patients; 11308 had been treated with EES. After 12 months of aspirin and thienopyridine, from 9961 overall eligible patients, 4703 EES patients were randomized to aspirin and placebo vs. aspirin and thienopyridine for 18 more months. Stents were chosen according to operators’ criteria, which is why the subanalysis was post hoc.
In EES patients, continued DAPT beyond a year reduced thrombosis (0.3% vs. 0.7%, HR 0.38, CI 95% 0.15-0.97; p=0.04) and AMI rates (2.1% vs. 3.2%, HR 0.63, CI 95% 0.44-0.91; p=0.01) compared to the placebo group, but did not reduce the composite of death, infarction or stroke (4.3% vs. 4.5%, HR 0.89, CI 95% 0.67-1.18; p=0.42).
Prolonged DAPT did increase moderate/severe bleeding (2.5% vs. 1.3%, HR 1.79, CI 95% 1.15-2.80; p=0.01) and all cause death (2.2% vs. 1.1%, HR 1.80, CI 95% 1.11-2.92, p=0.02).
Conclusion
In patients receiving PCI with EES, continued DATP beyond a year significantly reduces in-stent thrombosis and infarction, but increases bleeding, compared to aspirin alone.
Editorial Comment
The kind of stent was not pre specified in the protocol, which is why these observations call for cautions interpretation.
The rise in all-cause mortality in the EES group with prolonged DATP was mainly non- cardiac cancer-related (many of these cancers had been previously diagnosed), not due to major bleeding, as it had been expected. Notably, the group treated with conventional stents and DATP beyond a year did not render a higher mortality rate due to cancer, which may indicate this effect could be attributed to chance.
The number needed to treat (NNT) with prolonged DATP to prevent in-stent thrombosis is 235, and to prevent infarction, 98. On the other hand, the NNT to produce moderate to severe bleeding is 84.
These figures clearly show that DATP time should be decided individually on a case by case basis.