Syncope in adults with pulmonary arterial hypertension

Objectives: The aim of this study was to determine the prognostic significance of syncope in pulmonary arterial hypertension (PAH). Background: Some patients with PAH have a history of syncope at presentation. The prognostic implications of syncope in PAH have not yet been well characterized. Methods: This was a single-center cohort study of 378 patients with PAH seen at a dedicated pulmonary hypertension clinic over an 8-year period. All patients completed a standardized symptom assessment at the time of diagnosis. Results: Forty-five (12%) patients had a history of syncope at the time of PAH diagnosis. There were no significant differences in sex, age, functional class, 6-min walk distance, or etiology of PAH in syncopal versus nonsyncopal patients. Syncopal patients presented with higher right atrial pressure and lower cardiac outputs with lower survival rates (1-, 3-, and 5-year rates): 69% (95% confidence interval [CI]: 54% to 81%); 51% (95% CI: 36% to 65%); and 37% (95% CI: 24% to 53%), respectively, compared with 82% (95% CI: 77% to 86%); 64% (95% CI: 64% to 69%); and 54% (95% CI: 48% to 59%), respectively, in nonsyncopal patients. Syncope was a significant predictor of mortality (hazard ratio: 1.94, 95% CI: 1.20 to 2.99), after adjusting for age, sex, functional class, 6-min walk distance, diffusing capacity of carbon monoxide, and right atrial pressure. Syncopal patients had similarly poor outcomes compared with nonsyncopal patients presenting with class 4 symptoms. Conclusions: Syncope in PAH is associated with worsening right heart function and is an independent predictor of a poor prognosis.