Six months of dual antiplatelet therapy safe after PCI: study

In the era of second generation drug-eluting stents there is no need to extend the duration of dual antiplatelet therapy (DAPT) beyond six months after percutaneous coronary intervention (PCI) for ST-elevation myocardial infarction (STEMI), a Dutch study has shown.

A randomised controlled trial involving 870 patients undergoing primary PCI found that six months of DAPT was non-inferior to 12 months of therapy for a composite outcome at 24 months of all cause mortality, MI, revascularisation, stroke, and thrombolysis.

Published in the BMJ, the study showed that the primary endpoint occurred in 4.8% of patients who switched to aspirin only after six months following PCI, versus 6.6% of patients who received DAPT for 12 months (hazard ratio 0.73, P=0.26).

The trial results showed that non-inferiority was met for the composite outcome, although the number of participants was too low to make firm conclusions on specific outcomes such as thromboembolic events and bleeding, the study investigators said.

The major secondary endpoint, a composite of safety and bleeding at 24 months after the primary PCI, occurred in 3.2% in the six month DAPT group versus 4.3% in the 12-month DAPT group (hazard ratio 0.75; P=0.40).

There were no statistically significant differences between the groups in the incidence of all-cause mortality (0.7% v 1.4%); death from cardiac causes (0.5% v 0.9%); any myocardial infarction (1.8% v 1.8%); stent thrombosis (0.7% v 0.9%); stroke (0.7% v 0.7%); and thrombolysis in myocardial infarction major bleeding (0.2% v 0.5%)

The DAPT used was aspirin  75-100 mg orally daily and a P2Y12 inhibitor such as prasugrel, ticagrelor, or clopidogrel.

The study authors led by Dr Elvin Kedhi, a cardiologist at the Isala Clinic, Zwolle, Netherlands, said 12-month DAPT for PCI had been adopted in guidelines to prevent stent thrombosis based more on “expert opinion” than good trial evidence in the era of bare metal stents.

However, with the advent of second generation drug-eluting stents with lower rates of stent thrombosis there was concern that the increased risk of bleeding from DAPT may counteract any protection against thrombotic events, they said.

“Despite large scale trials evaluating the role of longer DAPT regimens in post MI patients showing some benefit for longer DAPT in reducing cardiovascular events, these reductions came with a high price in bleeding, which in turn is strongly related to mortality,” noted Dr Kedhi in a commentary.

“As expected we found that based on a net patient oriented outcome, a six month DAPT regimen is equally safe.”

“Although it may not be sufficient to change current guidelines, we are particularly glad that we could provide a well-founded answer to our patients that shorter DAPT regimens are safe even after STEMI, if  clinically needed,” he concluded.


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