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

Background: 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.

Methods: 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.

Results: 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.

Conclusions: 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.