Atrial fibrillation, venous thromboembolism, and risk of pulmonary hypertension: A Swedish Nationwide Register Study

Background Atrial fibrillation (AF) is a recognized risk factor for systemic arterial- and venous thromboembolism (VTE), including pulmonary embolism (PE), and may thereby contribute to the development of chronic thrombo-embolic pulmonary hypertension (PH). AF may also play a direct role in the development of post-capillary PH. We aimed to investigate the association between AF - with or without incident VTE - and the occurrence of PH. Methods A total of 521 988 patients diagnosed with AF between 1987–2013, without a previous diagnosis of VTE or PH, were identified from the Swedish National Patient Register (NPR) and matched for age, sex, and county with 1 017 277 population controls without AF, VTE or PH. Results The mean age of the AF patients was 71.1 (SD ±10.1) years and 42.8 % were women. During a median follow-up period of 11 (IQR 5.1,17) years, 4 454 (0.9%) AF patients and 1 855 (0.2%) controls were diagnosed with PH, HR 4.7 (4.4-5.0). The AF group had a significantly higher comorbidity burden at baseline, with a mean CHA 2 DS 2 -VASc of 2.9 compared to 2.1 in controls. In the absence of intercurrent VTE, the HR of PH was 4.2 (3.9-4.5) among AF patients compared to controls. Intercurrent VTE increased the HR of PH a further 1.9-fold (1.7-2.1) and 3.5 (3.1-4.0), among AF patients and controls, respectively. The HR for PH in AF patients with incident VTE was 8.1 (7.3-9.1). Conclusion AF was associated with a markedly increased risk of developing incident PH, and this risk was further increased by incident VTE.