Plasmatic variability of direct oral anticoagulants in people with atrial fibrillation and previous gastric surgery: a pilot case series

Data on cardioembolic prevention with direct oral anticoagulants (DOAC) in atrial fibrillation (AF) patients with previous gastric surgery are lacking. We report inter- and intra-individual differences in DOAC concentration in people with gastric surgery, to identify potential treatment options. Patients with previous gastric surgery receiving DOAC for AF as stroke secondary prevention, and undergoing peak-trough DOAC plasmatic testing were selected from the regional EDDIE-AF registry. DOAC levels were tested at least 75-102 h after DOAC initiation with Siemens Innovance® assays. Eight patients with previous gastric surgery were included (mean age 75 years, 50% women). Overall, only 20/36 tests were within range (55.5%; apixaban 75.0%; dabigatran 0%; edoxaban 64.3%; rivaroxaban 33.3%). Rivaroxaban and dabigatran failed to reach therapeutic peak-trough concentrations. Apixaban and edoxaban reached therapeutic levels in 4/6 and 3/7 cases respectively, with marginal out-of-target concentrations in all remaining cases. Our data support a consistent variability in DOAC absorption after gastric surgery, suggesting that implementation of DOAC plasmatic testing may help in ensuring therapeutic levels are met whenever DOACs are preferred over warfarin.