Syncope in Adults With Pulmonary Arterial Hypertension

Study Questions:

What is the prognostic significance of syncope in pulmonary arterial hypertension (PAH)?

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. Long-term follow-up of patients was presented on the basis of the Kaplan-Meier product-limit method and compared between groups with the log-rank test.

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-minute 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], 54-81%; 51%, 95% CI, 36-65%; and 37%, 95% CI, 24-53%, respectively, compared with 82%, 95% CI, 77-86%; 64%, 95% CI, 64-69%; and 54%, 95% CI, 48-59%, respectively, in nonsyncopal patients. Syncope was a significant predictor of mortality (hazard ratio, 1.94; 95% CI, 1.20-2.99), after adjusting for age, sex, functional class, 6-minute walk distance, diffusing capacity of carbon monoxide, and right atrial pressure. Syncopal patients had similarly poor outcome, compared with nonsyncopal patients, with class 4 symptoms.

Conclusions:

The authors concluded that syncope in PAH is associated with worsening right heart function, and is an independent predictor of a poor prognosis.

Perspective:

The study suggests that 12% of newly diagnosed PAH patients may have a recent history of syncope. Syncope appears to be associated with impaired right heart function and correlates poorly with functional status. Furthermore, syncope is linked to an increased risk of death that is incremental to the risk attributable to other recognized prognostic factors. Further studies are indicated to elucidate the mechanism of syncope in PAH and to determine the impact of different therapies on the frequency and significance of syncope during the course of the disease.

Clinical Topics: Arrhythmias and Clinical EP, Heart Failure and Cardiomyopathies

Keywords: Prognosis, Follow-Up Studies, Atrial Pressure, Survival Rate, Syncope, Cardiac Output


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