A comparison of randomized clinical trials that assessed dual-antiplatelet therapy (DAPT) durations showed such trials should include treatment periods and case fatality rates to better understand the risks and benefits. Using this approach, researchers saw hints of a mortality advantage with 12-month DAPT.

Raban V. Jeger, MD, of University Hospital Basel in Switzerland, and colleagues compared outcomes from two clinical trials that evaluated different clopidogrel-based DAPT durations—six months (BASKET) and 12 months (BASKET-PROVE)—in patients with acute coronary syndrome treated with bare-metal vs. drug-eluting stents. Longer-term DAPT may increase bleeding risk while shorter-term DAPT may not prevent stent thrombosis (ST).

“Because the clinical relevance of ST and major bleeding (MB) usually is not the same, complications, that is, case fatality rates, should be considered,” they wrote in the November issue of the American Heart Journal. “In addition, the benefit-risk ratio of these events may differ during effective treatment periods, in contrast to the entire study duration.”

The periods they focused on were the seven- to 12-month follow-up in BASKET-PROVE, the zero to six-month span in BASKET and the 13- to 24-month period in both trials when patients received only aspirin. They selected patients treated with 3 mm or greater stents for their analysis.

Twelve-month vs. six-month DAPT had lower rates of ST and cardiac death and nonfatal MI as well as reduced ST rates for all three periods. Bleeding events were lower in the first six months for 12-month vs. six-month DAPT but higher in the seven- to 12-month period.

Overall, they found 42 cases of definite or probable stent thrombosis, with 13 fatalities; and 53 MB events, with six fatalities. In the seven- to 12-month period, they determined that the use of 12-month DAPT compared with six-month DAPT led to 85 fewer cases of ST but 43 more MB events per 10,000 patients.

Jeger et al calculated the net clinical benefit of long- vs. short-term DAPT totaled one life per 1,000 patients per year.

“[T]he expected death rate with prolonged DAPT was 6-fold lower than with the shorter regimen if extrapolated from the present study,” they wrote. “An implication might be that prolongation of DAPT after 6 months may be clinically indicated, provided that there are no contraindications against DAPT.”

The event rates in the analysis were low, they pointed out, making the results hypothesis-generating only.