Syncope in Adults With Pulmonary Arterial Hypertension: Characterization and Prognostic Implications

Abstract

PURPOSE: The frequency of syncope and its role in defining functional status and prognosis in adults with pulmonary arterial hypertension (PAH) remains ill defined. The focus of this work was to characterize the clinical and hemodynamic features of syncopal PAH patients and define their prognosis. METHODS: Single center cohort study of 475 adult patients with Group 1 PAH first seen between 1995 and 2006. All patients completed a standardized symptom assessment at the time of diagnosis. Initial clinical, echocardiographic and hemodynamic data were compiled and longterm mortality data. RESULTS: At the time of PAH diagnosis 53 (11.2%) patients had a history of syncope. There were no significant differences in gender, age, NYHA functional class, six-minute walk distance or PAH etiology in syncopal versus non-syncopal patients. The echocardiographic characteristics of syncopal patients versus non-syncopal included more patients with severe right atrial and right ventricular enlargement. Syncopal patients had higher right atrial pressures and lower cardiac outputs at right heart catheterization. One, 3 and 5 years survival was lower in syncopal (73%, 55%, 41%) versus non-syncopal (86%, 70%, 55%; p<0.01) patients. After factoring in age, sex, NYHA dyspnea class, etiology of PAH, 6 minute walk distance, findings on echocardiography and right heart catheterization; syncope remained the strongest factor associated with death [hazard ratio 2.56 (95% confidence interval 1.26, 4.84)]. PAH played a primary or secondary role in mortality for the majority of patients, with death invariably preceded by a progressive decline in functional status and advancing right heart failure. There was no apparent difference between syncopal and non-syncopal patients. Unexpected sudden death occurred infrequently and did not occur more commonly in the syncopal group. CONCLUSION: In a broad spectrum of clinical PAH patients, syncope is infrequent, associated with markers of right heart dysfunction and is strongly and independently predictive of poor outcome. CLINICAL IMPLICATIONS: Patients who have a history of syncope when diagnosed with PAH have a poor prognosis.