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PRODIGY study: appropriate duration of dual antiplatelet therapy after coronary stenting

A randomised multicentre open-label study was evaluating the efficacy and safety of prolonged antiplatelet therapy in patients with coronary disease has found that 24 months' duration of dual therapy is no better than six months DAPT in preventing adverse cardiac events.

However, the PRODIGY ( PROlonging Dual antiplatelet treatment after Grading stent-induced Intimal hyperplasia studY ) trial also found a consistently greater risk of haemorrhage in the 24-month dual therapy group according to all prespecified bleeding definitions, including the recently proposed Bleeding Academic Research Consortium ( BARC ) classification.
The need for transfusion was also increased in the longer treatment group.

According to Marco Valgimigli from the University Hospital of Ferrara ( Italy ), the results question the validity of current guideline recommendations, which are based on registry data, that at least 12 months' dual antiplatelet therapy should be pursued after implantation of a drug-eluting stent.

The PRODIGY study was a 4-by-2 randomised, three-centre open-label clinical trial designed to assess the efficacy and safety of prolonged Clopidogrel ( Plavix ) therapy for up to 24 months in all-comer patients receiving a balanced combination of drug-eluting stents ( with various anti-intimal hyperplasia potency and belonging to both first and second generation ).
Patients were 18 years or older with chronic stable coronary artery disease or acute coronary syndromes, including non-ST-elevation and ST-elevation myocardial infarction.

More than 2000 patients scheduled for elective, urgent or emergency coronary angioplasty were randomly assigned in a 1:1:1:1 fashion to one of four stent types: Everolimus-eluting stent ( Xience ), Paclitaxel-eluting stent ( Taxus ), Zotarolimus-eluting stent ( Endeavor ) or third-generation thin-strut bare metal stent.
Randomisation to the four different types was justified by the different safety profile of each, which was meant to ensure that patients in the two main study groups ( 6 versus 24 month dual antiplatelet therapy ) received exactly the same stent types.
At 30 days, patients in each stent group were then further randomised to either 6 or 24 months of dual antiplatelet treatment.

The primary objective of the study was to assess whether 24-month dual antiplatelet treatment, consisting of Clopidogrel and Acetylsalicylic acid ( Aspirin ) after coronary stenting, was associated with a lower cumulative incidence of all-cause mortality, non-fatal myocardial infarction or cerebrovascular accident ( the primary outcome ) than six-month dual therapy.

Results showed that the cumulative risk of the primary outcome at two years was 10.1% with the 24-month treatment, and 10.0% with the 6-month ( hazard ratio, HR=0.98; 95% CI 0.74-1.29; P=0.91 ).
The individual risks of death, myocardial infarction, cerebrovascular accident or stent thrombosis did not differ between the two groups.

Among the patients receiving long-term dual antiplatelet therapy, there was a roughly two-fold greater risk of type V, III or II bleeding events ( HR=2.17, 95% CI 1.44-3.22; p=0.00018 ) as well as type V or III bleeding events ( HR=1.78, 95% CI 1.02-3.13; p=0.037 ) according to the Bleeding Academic Research Consortium classification.
The risks of TIMI-defined major bleeding and red blood cell transfusion were also increased in the 24-month Clopidogrel group.

Source: European Society of Cardiology ( ESC ) Meeting, 2011