Age no barrier to vorapaxar use in ACS
medwireNews: The protease-activated receptor 1 inhibitor vorapaxar offers the same benefits to older and younger patients with non-ST segment elevation acute coronary syndromes, shows further analysis of the TRACER trial.
Although patients older than 75 years had an increased bleeding risk, they also had an increased risk of thromboembolic events and cardiovascular death, so the risk–benefit ratio was similar to that in younger patients.
“Advanced age is associated with increased anticoagulant proteins, clotting factors, and plasma viscosity resulting in a thrombotic state; reduced vascular repair capacity; impaired endothelial cell regeneration capacity and vascular fragility from amyloid angiopathy; and loss of collagen surrounding the vasculature”, say Renato Lopes (Duke Clinical Research Institute, Durham, North Carolina, USA) and study co-authors.
“Therefore, it is important to provide specific age-based data evaluating efficacy and bleeding risk of antithrombotic regimens.”
The median age of the 12,944 patients in the TRACER (Thrombin Receptor Antagonist for Clinical Event Reduction in Acute Coronary Syndrome) trial was 64 years, with 17.1% being at least 75 years of age (40.1% were female).
Overall, the likelihood of moderate or severe haemorrhagic events rose with older age, from 2.7% in the youngest age group (≤54 years) to 11.7% in the oldest patients (≥75 years), equating to a significant 3.27-fold increased risk in the oldest versus the youngest groups. And the same was true for ischaemic events (myocardial infarction, stroke, cardiovascular death), with rates rising from 17.0% to 26.5%, equating to a significant 1.36-fold increase.
Patients were randomly assigned to receive vorapaxar at a loading dose of 40 mg after randomisation and 1 hour before any revascularisation and then 2.5 mg daily for at least 1 year, or matching placebo. Use of vorapaxar rather than placebo reduced the risk of ischaemic outcomes in all age groups, and tended to increase the risk of bleeding in all age groups – significantly in some but not others, with no age-related increase.
Likewise, the effect of vorapaxar on the net clinical benefit did not vary by age, the researchers report in the American Heart Journal.
“Importantly, we did not observe an interaction of vorapaxar with age on bleeding, despite vorapaxar being used in the context of dual antiplatelet therapy and widespread use of invasive management”, they say.
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