Pulmonary hypertension: An unexplored risk factor for stroke in patients with atrial fibrillation

Atrial fibrillation (Afib) is one of the most common and significant risk factors for stroke, with the CHADsVAsc score used as the tool for stroke risk assessment. Pulmonary hypertension (PH) has not been studied as an independent risk factor for stroke in individuals with Afib.

In this retrospective case-control study, National Inpatient Sample Database was used to sample individuals with atrial fibrillation, and baseline demographics and comorbidities were collected using ICD-10 codes. Patients with missing data, age under 18, history of thromboembolic diseases, or stroke were excluded. Greedy propensity matching using R was performed to match patients with and without PH on age, race, gender, and 19 other comorbidities, including anticoagulation use. Binary logistic regression was performed after matching to assess whether PH was an independent risk factor for stroke. A p-value of <0.05 was considered statistically significant.

Of the 2,421,545 patients included in the study, 158,545 (6.5%) had PH. PH patients were more likely to be elderly, females, and smokers. Comorbidities were more common in the PH group. Patients with PH were more likely to have an ischemic stroke (3.6% vs. 2.9%, p<0.001), hemorrhagic stroke (2.2% vs. 0.7%, p<0.001), and transient ischemic attack (TIA) (2.3% vs. 0.7%, p<0.001). After matching, the presence of PH was associated with increased ischemic stroke (OR: 1.2 [1.1-1.2]; p<0.001), hemorrhagic stroke (OR: 2.4 [2.1-2.6]; p<0.001) and TIA (OR: 2.2 [2.0-2.4]; p<0.001). PH patients also had increased length of stay (β = 0.8; p<0.001) mortality (OR: 1.1 [1.0-1.2]; p<0.001).

Apart from demonstrating the deleterious effect of PH on mortality and length of hospital stay, this study is the first to report on such a large scale that PH independently increases the incidence of all types of strokes in patients with Afib.