BACKGROUND: Atrial fibrillation (AF) is suggested to be associated with venous thromboembolism (VTE) and might thereby play a role in the development of chronic thromboembolic pulmonary hypertension (PH). By elevating left-sided filling pressure and promoting atrial myopathy, AF may also play a role in the development of postcapillary 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 and 2013, without a previous diagnosis of VTE or PH, were identified from the Swedish National Patient Register and matched for age, sex, and county with 1 017 277 population controls without AF, VTE, or PH.

RESULTS: The mean age of the patients with AF was 71.1 (SD ±10.1) years and 42.8% were women. During a median follow-up period of 11 (interquartile range 5.1-17) years, 4454 (0.9%) patients with AF, and 1855 (0.2%) controls were diagnosed with PH, hazard ratio 4.7 (4.4-5.0). The AF group had a significantly higher comorbidity burden at baseline, with a mean CHA₂DS₂-VASc of 2.9 compared with 2.1 in controls. In the absence of intercurrent VTE, the hazard ratio of PH was 4.2 (3.9-4.5) among patients with AF compared with controls. Intercurrent VTE increased the hazard ratio of PH a further 1.9-fold (1.7-2.1) and 3.5 (3.1-4.0), among patients with AF and controls, respectively. The hazard ratio for PH in patients with AF with incident VTE was 8.1 (7.3-9.1).

CONCLUSIONS: AF was associated with a markedly increased risk of developing incident PH, and this risk was further increased by incident VTE.