Aims: Mechanical aortic valve replacement (AVR) remains the primary treatment for younger patients with severe aortic valve disease. However, limited information is available regarding the quality of the required lifelong vitamin K antagonist (VKA) therapy, atrial fibrillation (AF), and their relationship with adverse events after AVR. This study assessed the quality of VKA therapy prior to bleeding and ischaemic events following mechanical AVR in patients with AF.

Methods and results: The registry-based Finnish AntiCoagulation in Atrial Fibrillation study combining data from several Finnish healthcare registers covers all patients diagnosed with AF during 2007-18 in Finland. This analysis included patients undergoing mechanical AVR before or after the AF diagnosis. A total of 1086 patients with mechanical AVR and AF either before (41.2%) or after (58.8%) the operation were identified. Cumulative incidence estimates at 10 years after AVR were 27.9% for significant bleeding, 5.8% for intracranial haemorrhage, 12.8% for ischaemic stroke, and 7.2% for myocardial infarction. Time in therapeutic range (TTR) < 80% with international normalized ratio (INR) target 2.0-3.5 was associated with higher bleeding occurrence [adjusted hazard ratio (aHR) 1.97, 1.39-2.79, P < 0.001]. Time in therapeutic range with INR target ≥2.0 was associated with higher stroke occurrence (aHR/standard deviation 1.22, 1.01-1.46, P = 0.035). Mortality was high (28.9%/10 years), and TTR <80% was associated with higher mortality (aHR 2.74, 2.00-3.76, P < 0.001).

Conclusion: Adverse events, particularly major bleeding, are common in patients with AF following mechanical AVR, and mortality is high. Suboptimal TTR appears to predict bleeding episodes, ischaemic stroke, and death, and it could be useful in high-risk patient identification and targeting of preventive strategies.