Conference Coverage

Optimal medical therapy doesn’t affect DAPT efficacy




ROME – Continued dual-antiplatelet therapy beyond 12 months after coronary stenting is neither helped nor hindered by concomitant background optimal medical therapy, according to a secondary analysis of the landmark DAPT trial.

Numerous studies have shown that only 46%-66% of patients with stable ischemic heart disease are adherent to guideline-directed optimal medical therapy (OMT) with statins, beta-blockers, and ACE inhibitors or angiotensin receptor blockers. Yet until this new analysis from DAPT (the Dual Antiplatelet Therapy Study), the impact of OMT on the treatment effect of prolonged DAPT was unstudied, Charles D. Resor, MD, said at the annual congress of the European Society of Cardiology.

Dr. Charles D. Resor Bruce Jancin/Frontline Medical News

Dr. Charles D. Resor

It was plausible that the treatment benefit of continued DAPT beyond 12 months after coronary stenting might be stunted by concomitant OMT, or alternatively that OMT and DAPT might exert synergistic effects in reducing the risk of ischemic events. As it turned out, neither of these possibilities turned out to be the case, according to Dr. Resor of Brigham and Women’s Hospital, Boston.

“I think OMT is underutilized, but while we would like physicians to emphasize OMT use in more cases, the decision to use DAPT beyond 12 months should be made irrespective of OMT use,” he said.

“That’s an important message for clinicians,” commented session cochair Keith A.A. Fox, MD, of the University of Edinburgh.

The landmark DAPT trial established that there is a significant benefit of continued dual-antiplatelet therapy beyond 12 months from coronary stenting in patients with stable ischemic heart disease (N Engl J Med. 2014 Dec 4;371:2155-66). Dr. Resor presented a secondary analysis of clinical outcomes in 11,643 study participants stratified by their OMT status as well as by whether they were randomized to dual-antiplatelet therapy or aspirin plus placebo.

Sixty-three percent of subjects were on OMT at enrollment. Adherence to OMT was high: At 30 months post stenting, 62% of participants remained on OMT.

Between 12 and 30 months after percutaneous coronary intervention, continued dual-antiplatelet therapy in patients also on OMT was associated with a 2.1% incidence of acute MI, a 36% reduction in risk, compared with the 3.3% rate in subjects on placebo plus OMT. In patients not on OMT, the MI rate was 2.2% in those on dual-antiplatelet therapy versus 5.2% with placebo, for a 59% relative risk reduction in the active treatment arm.

The rate of the composite endpoint of major adverse cardiovascular and cerebrovascular events in patients on dual-antiplatelet therapy and OMT was 4.2%, compared with a 5.0% rate in patients on placebo and OMT.

Moderate or severe bleeding, as measured by the Global Use of Strategies to Open Occluded Arteries (GUSTO) criteria occurred in 2.2% of patients on dual-antiplatelet therapy and OMT, compared with 1.0% in those on placebo plus OMT. In patients not on OMT, the bleeding rate was 2.8% in the dual-antiplatelet therapy group and 2.2% with placebo, a nonsignificant difference.

Overall, patients on OMT had significantly lower rates of acute MI than those not on OMT (2.7%, compared with 3.7%), as well as fewer major adverse cardiovascular and cerebrovascular events (4.6% versus 5.7%), and less moderate or severe bleeding (1.6%, compared with 2.5% in patients not on OMT). However, rates of stroke, stent thrombosis, and death didn’t differ between patients on OMT and those who were not.

“While the associations between OMT use and lower rates of MI and MACCE [major adverse cardiovascular and cerebrovascular events] were expected, the association with lower rates of moderate or severe bleeding was not; we suspect the lower bleeding risk is mostly due to some residual confounding,” according to Dr. Resor.

He reported having no financial conflicts of interest regarding the new secondary analysis of DAPT, which was sponsored by the Harvard Clinical Research Institute.

Simultaneously with Dr. Resor’s presentation, the new DAPT study analysis was published online (Circulation. 2016 Aug 30. doi: 10.1161/CIRCULATIONAHA.116.024531.)

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