Rate and risk factors for thromboembolism and major bleeding in adults with congenital heart disease taking vitamin K antagonist therapy

The risk of adults with a congenital heart defect (ACHD) developing heart failure, stroke, arrhythmias, and the need for valve replacement is increased compared to healthy peers. Evidence for the use of novel oral anticoagulants (NOAC) in this patient group is still lacking and vitamin K antagonists (VKA) are the primary choice for patients with a mechanical valve. The present aim was to determine the rate of thromboembolic and major bleeding events in ACHD patients on VKA therapy. This was a retrospective study on ACHD patients on VKA treatment registered in the National Quality Registry for Congenital Heart Disease, SWEDCON, and Atrial fibrillation and Anticoagulation, AuriculA, from Southern Sweden. 213 patients were included with a mean age of 50 years (±18) years and a mean follow-up of 6.6 years (±3.3 years), 16% had complex defects and 41% had valvular VKA therapy indication. In total, 34 complications were registered, of which 14 were thromboembolic events and 20 were major bleeding events. The rate of thromboembolism and major bleeding events was 1.0 (95% CI: 0.6–1.6) and 1.4 (95% CI: 0.9–2.2) per 100 patient-years, respectively. Forty-three patients died during the study period. The mortality rate was 3.1 per 100 patient-years (95% CI: 2.2–4.1). We found a low rate of thromboembolic events and major bleeding events for low-moderate risk ACHD patients with good quality of VKA anticoagulation. The target of TTR>65% for ACHD patients is recommended.