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.