"Longer is better." That's what Dr. Dean Kereiakes told Angioplasty.Org when characterizing the results of the long-awaited Dual Antiplatelet Therapy (DAPT) study, which were presented today at the annual American Heart Association Scientific Sessions in Chicago. Dr. Kereiakes is the co-principal investigator for this five year study of 10,000 patients, which adds to the knowledge base of whether long-term treatment with aspirin and a thienopyridine, such as Plavix, after stent implantation is beneficial to patients.

The DAPT trial was requested by the U.S. FDA after data in 2006 showed an increased risk of stent thrombosis (blood clotting inside a stent) with drug-eluting stents. For background on this issue, read our Editor's blog post, "Plavix and Aspirin After Stent: 8 Years Later – Is Longer Better?"

The study was presented at AHA today by Laura Mauri MD, MSc, principal investigator of the DAPT Study, interventional cardiologist at the Brigham and Women’s Hospital, Associate Professor of Medicine at Harvard Medical School and Chief Scientific Advisor for HCRI. The study was simultaneously published in the New England Journal of Medicine. The main question was whether 30 months of DAPT after stenting was superior to twelve, and the results favored the longer period. The study looked at the period starting one year after stent implantation in 9,961 patients who had received drug-eluting stents and who had been on DAPT (aspirin plus an antiplatelet drug, most commonly clopidogrel/Plavix) for the previous twelve months. At this point the patients were randomized: half continued on DAPT and the other half were given a placebo plus aspirin.

The results at 30 months showed significantly lower rates of stent thrombosis in the DAPT group (0.4% vs 1.4%, p<.001) and lower rates of heart attack in the DAPT group (2.1% vs 4.1%, p<.001). Severe or moderate bleeding predictably was higher in the DAPT group (2.53% vs 1.57%, p=.001). However, none of these differences translated to a significant change in overall mortality, and surprisingly the non-cardiovascular death rate was higher in the DAPT group. The investigators posited that this may have been due to the fact that more patients with cancer wound up being randomized into the extended DAPT cohort.