Consequences of the Poor Anticoagulation Control of Patients with Non-Valvular Atrial Fibrillation Treated with Vitamin K Antagonists

Background: The prevention of thromboembolisms through anticoagulation and heart rate control is crucial in managing non-valvular atrial fibrillation (NVAF). This study aimed to analyze the consequences of poor anticoagulation control with vitamin K antagonists (VKAs) in Spanish patients with NVAF, focusing on thrombotic events, bleeding, mortality, healthcare resources (HRU), and costs. Methods: This observational, retrospective study used electronic medical records (BIG-PAC^® database) of NVAF patients who started VKA treatment between 1 January 2016 and 31 December 2018. Patients were followed up for two years and classified by poor or adequate anticoagulation control. Demographic and clinical characteristics, treatments, incidence of cardiovascular events, mortality rates, HRU, and costs were analyzed. Results: Patients with poor control (n = 2136) had a 75% greater probability of suffering a cardiovascular event compared to patients with adequate control (n = 2351) (HR, 1.75 [95%CI: 1.43-2.14; p < 0.001]). Cardiovascular events, major bleeding, minor bleeding, systemic thromboembolism, and ischemic strokes were reduced by 32.1%, 46.2%, 29.6%, 22.2%, and 16.1%, respectively. It was estimated that adequate anticoagulant control saved EUR 455/patient with NAVF due to reduced hospitalization for cardiovascular events. Conclusions: For VKA-treated NVAF patients, poor anticoagulation control was associated with a higher number of cardiovascular events, greater consumption of HRU, and higher management costs than for patients with adequate control.