Efficacy and safety of apixaban compared with aspirin in patients who previously tried but failed treatment with vitamin K antagonists: results from the AVERROES trial

Aim The AVERROES double-blinded, randomized trial demonstrated that apixaban reduces the risk of stroke or systemic embolism (SSE) by 55% compared with aspirin without an increase in major bleeding in patients with atrial fibrillation either who previously tried but failed vitamin K antagonists (VKA) therapy or who were expected to be unsuitable for VKA therapy. In this pre-specified analysis, we explored the consistency of the results in the subgroup of patients who tried but failed VKA therapy. Methods and results Of 5599 patients, 2216 (40%) had previously failed VKA treatment [main reasons: poor international normalized ratio (INR) control 42%, refusal 37%, bleeding on VKA 8%]. Compared with those expected to be unsuitable for VKA therapy, those who had previously failed were older, more often male, had higher body mass index, more likely to have moderate renal impairment and a history of stroke and less likely to have heart failure or to be medically undertreated. The effects of apixaban compared with aspirin were consistent in those who previously failed and those who were expected to be unsuitable, for both SSE (P interaction 0.13) and major bleeding (P interaction 0.74) and were also consistent among different subgroups of patients who had previously failed VKA therapy defined by reasons for unsuitability, age, sex, renal function, CHADS(2) score, aspirin dose, duration, indication, and quality of INR control of prior VKA use. Conclusion The efficacy and safety of apixaban compared with aspirin is consistent in subgroups of patients who have previously attempted but failed VKA therapy, irrespective of the reason for discontinuation.