Why is this study important?

The presentation at TCT2021 represents the prespecified acute coronary syndromes (ACS) subgroup analysis of the MASTER DAPT study, the overall results of which were presented at ESC 2021 earlier this year. This analysis focused on patients both at high bleeding risk (HBR) and high ischemic risk and found that independent of MI history, abbreviated (1-month DAPT) following PCI was non-inferior to 3-months of DAPT for ischemic events and moreover, abbreviated DAPT was associated with a reduction in bleeding events.

Should I change my practice because of these findings?

The findings of the main MASTER DAPT trial and the ACS subgroup analysis presented at TCT2021 strengthen the case for short-DAPT even in HBR populations we traditionally believed to be at exaggerated ischemic risk and may, therefore, benefit from longer duration of DAPT. That said, a specific non-FDA-approved DES was mandated by study protocol during the index PCI procedure and thus these data cannot be generalized to other DES platforms including those commonly used in the United States.

What question was this study supposed to answer?

This ACS subgroup analysis investigated the optimal duration of DAPT in post-PCI patients who are both at HBR as well as high risk for future ischemic events. The overall MASTER-DAPT trial randomized 4,579 HBR patients who had undergone PCI with an ultrathin sirolimus-eluting stent (Ultimaster, Terumo) to conclude DAPT (aspirin plus P2Y12 inhibitor) at the 30-day mark vs. continue DAPT for at least 2 more months. Single antiplatelet therapy with either aspirin or a P2Y12 inhibitor could be continued up to 11 months if needed. Patients were stratified in this analysis on the basis of prior MI within the past 12 months and followed for major adverse cardiac or cerebrovascular events (MACCE), net adverse clinical events (NACE), and bleeding events. Of the patients randomized to abbreviated DAPT 914 (39.8%) patients had a prior MI in the last 12 months vs. 1,381 patients who had not. In the 3-month+ DAPT arm, 866 (37.9%) patients had a prior MI in the last 12 months vs. 1,418 patients who had not.

What did the study show?

The ACS analysis of MASTER DAPT recapitulated the topline results of the main study:  the rates of net adverse clinical events and MACCE did not differ between the two arms (abbreviated vs. non-abbreviated DAPT).

With regard to the comparison of patients with vs. without a prior MI within 12 months, 1 year NACE (all-cause death, MI, stroke and BARC 3 or 5 bleeding) did not differ by DAPT strategy in those with a prior MI (HR = 0.83; 95% CI, 0.61-1.12; P = .22) and in those without prior MI (HR = 1.03; 95% CI, 0.77-1.38; P = .85; P for interaction = .3).  Similarly, 1-year MACCE (all-cause death, MI or stroke) also not differ by DAPT treatment strategy in those with a prior MI (HR = 0.86; 95% CI, 0.62-1.19; P = .36) and in those without prior MI (HR = 1.13; 95% CI, 0.8-1.59; P = .48; P for interaction = .25).

The observed reductions in BARC 2, 3, or 5 bleeding events with abbreviated DAPT in the ACS analysis were consistent with the main trial findings and were similar irrespective of whether patients had a prior MI in the preceding 12 months.

How good was the approach/methodology?

MASTER DAPT was a large contemporary dataset that helps answer a pressing and clinically relevant question: where exactly does the balance of ischemic protection and freedom from bleeding lie in a HBR population? The findings of the overall trial as well as the ACS subgroup resonate with many other recently presented/published trials and reassure us that truncating DAPT after 1 month in HBR patients who underwent PCI with the Ultimaster DES, did not increase the risk of ischemic events even in those patients who had suffered an MI within the previous year. This abbreviation of therapy in the overall study population as well as in the various subgroups noted above was accompanied by significant reductions in bleeding, as compared with 3-months+ of DAPT.

All editors: Sandeep Nathan, MD, MSc, FSCAl; Kirk N. Garratt, MD, MSc, MSCAI; and David A. Cox, MD, MSCAI