DOACs trump warfarin for heart attack prevention in AFib patients
Compared to warfarin, the direct oral anticoagulants (DOACs) apixaban, rivaroxaban and dabigatran are all associated with a reduced risk of myocardial infarction, according to a Danish registry study of consecutive patients with nonvalvular atrial fibrillation (AFib).
The study included 31,739 subjects—median age 74; 47 percent women—and was published online June 25 in the Journal of the American College of Cardiology. Lead author Christina Ji-Young Lee, MD, and colleagues found risk-standardized, one-year MI rates ranged from 1.1-1.2 percent for each of the DOACs compared to 1.6 percent for the vitamin K antagonist (VKA) warfarin.
No significant risk differences were observed between the Factor Xa inhibitors, but each of them showed a statistically significant risk reduction versus warfarin.
“Compared with VKA, DOACs are not associated with an increased risk of MI,” Lee et al. wrote. “Presently, there are no results from randomized clinical trials directly comparing the DOACs head-to-head, although current evidence has not shown superiority of one DOAC over the other. Present evidence from supporting biological studies remains insufficient, and studies in sizeable cohorts comparing the effects of DOACs and VKAs on platelet function and reactivity continue to be wanted.”
In a secondary analysis using the combined endpoint of MI and all-cause mortality, dabigatran appeared to be slightly more protective than the other DOACs. Unadjusted cumulative incidence of that endpoint was 4.91 percent for dabigatran, 7.54 percent for apixaban, 10.6 percent for rivaroxaban and 8.69 percent for warfarin.
After risk adjustment, the combined endpoint was met in 5.75 percent of patients on dabigatran, 9.04 percent of patients on rivaroxaban, 6.25 percent of patients on apixaban and 8.61 percent of those on warfarin.
“The study by Lee et al. helps to settle the dust around an 8-year-old debate concerning the risk of MI in patients receiving DOAC therapy (and specifically dabigatran) for stroke prevention in AFib,” Stefan H. Hohnloser, MD, and John W. Eikelboom, MD, MBBS, wrote in a related editorial. “Based on the large and consistent body of evidence now available, clinicians can use dabigatran with even greater confidence in AFib patients, including those with a history of coronary artery disease and prior MI.”
Another strength of Lee and colleagues’ study, according to the editorialists, is it included patients with frailty and high comorbidity burdens that may have been excluded from the randomized trials evaluating DOACs.
Daniel joined TriMed’s Chicago editorial team in 2017 as a Cardiovascular Business writer. He previously worked as a writer for daily newspapers in North Dakota and Indiana.