Tradeoff between bleeding and stent thrombosis in different dual antiplatelet therapy regimes: Importance of case fatality rates and effective treatment durations

Background The tradeoff between stent thrombosis (ST) and major bleeding (MB) of 12- versus 6-month dual antiplatelet therapy (DAPT) after coronary stent implantation has not been clearly defined. Methods Definite/probable ST and MB (TIMI major and Bleeding Academic Research Consortium (BARC) >= 3) were compared in 2 subsequent trials with similar inclusion criteria but different DAPT duration, that is, BASKET (6 months; n = 557) and BASKET-PROVE (12 months; n = 2,314 between months 0 to 6 (DAPT in both trials), 7 to 12 (DAPT in BASKET-PROVE only), and 13 to 24 (aspirin in both trials) using propensity score-adjusted, time-stratified Cox proportional hazard models. Results Overall, event rates were low with fewer ST but similar MB in prolonged DAPT. Analysis of the 3 periods showed a uniform pattern for ST (interaction DAPT/period; P=.145) but an inconsistent pattern for MB (interaction DAPT/period; P<.001 for TIMI major and P=.046 for BARC >= 3), with more MB occurring during months 7 to 12 with prolonged DAPT. Considering observed case fatality rates of 31% with ST and 11% with MB, the extrapolated prevention of 27 ST deaths and the excess of 5 MB deaths resulted in an expected benefit of 22 survivors/10,000 patients treated over 2 years with prolonged DAPT. Conclusion Despite overall low event rates, prolonged DAPT was associated with more MB during months 7 to 12 according to the interaction DAPT/period. Given the higher observed case fatality rates of ST versus MB, 12- versus 6-month DAPT was associated with an extrapolated reduction in mortality. Effective treatment periods and case fatality rates seem important in the analysis of different DAPT durations, specifically with regard to ongoing trials.