The HOST-EXAM study (which was prospective, randomized, and open-label, with the participation of 37 Korean sites) was specifically designed to determine the role of aspirin as the long-term antiplatelet therapy of choice after angioplasty with current drug-eluting stents. To this end, the study compared aspirin head-to-head with clopidogrel.
Over the course of four years, 5438 patients (mean age 64 years, a third of them with acute coronary syndromes) were enrolled and randomized after angioplasty to 100 mg of aspirin vs. 75 mg of clopidogrel with a follow-up of over a year. Prior to randomization, patients had to have completed 6 to 18 months of dual antiplatelet therapy without an event.
The primary endpoint was a composite of all-cause mortality, infarction, stroke, readmission for acute coronary syndrome, and major bleeding (BARC 3 or over).
After two years of follow-up, the primary endpoint was observed in 5.7% patients in the clopidogrel group vs. 7.7% in the aspirin group (p = 0.0035).
This data is significant in favor of clopidogrel. The difference was driven by readmissions for acute coronary syndromes (2.5% vs. 4.1%; p = 0.001).
The other hard endpoints were identical. In fact, all-cause mortality (including death from cancer) tended to be lower in the aspirin group.
The HOST-EXAM study is not definitive and has a number of weaknesses that will likely keep aspirin in our arsenal for a while longer.
Read also: FLOWER-MI Sub-Studies Coming Out Generate More Questions about FFR.
For example, its open-label design was not free of event-reporting biases; the observed event rate was 36-% lower than expected—which reduces its statistical power or, even worse, confirms the underreporting of events. Furthermore, no genetic testing was performed in at least a representative sample of the enrolled population, despite knowing that about 50% of Asian individuals carry mutations that attenuate the effect of clopidogrel or directly render it ineffective.
Although HOST-EXAM raises questions about the role of aspirin as a long-term antiplatelet therapy, further pragmatic studies are needed to confirm (or disprove) its results.
Original Title: Challenging the Role of Aspirin for Long-Term Antiplatelet Therapy?
Reference: Leonarda Galiuto et al. Eur Heart J. 2021 Aug 7;42(30):2883-2884. doi: 10.1093/eurheartj/ehab387.
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