Rationale: Pulmonary arterial hypertension (PAH) related to systemic sclerosis (SSc) has a poorer prognosis compared with other forms of PAH for reasons that remain unexplained.
Objectives: To identify risk factors of mortality in a well-characterized cohort of patients with PAH related to systemic sclerosis (SSc-PAH).
Methods: Seventy-six consecutive patients with SSc (64 women and 12 men; mean age 61 ± 11 yr) were diagnosed with PAH by heart catheterization in a single center, starting in January 2000, and followed over time. Kaplan-Meier estimates were calculated and mortality risk factors were analyzed.
Measurements and Main Results: Forty (53%) patients were in World Health Organization functional class III or IV. Mean pulmonary artery pressure was 41 ± 11 mm Hg, pulmonary vascular resistance (PVR) was 8.6 ± 5.6 Wood units, and cardiac index was 2.4 ± 0.7 L/min/m2. Median follow-up time was 36 months, with 42 deaths observed. Survival estimates were 85%, 72%, 67%, 50%, and 36% at 1, 2, 3, 4, and 5 years, respectively. Multivariate analysis identified PVR (hazard ratio [HR], 1.10; 95% confidence interval [CI], 1.03–1.18; P < 0.01), stroke volume index (HR, 0.94; 95% CI, 0.89–0.99; P = 0.02), and pulmonary arterial capacitance (HR, 0.43; 95% CI, 0.20–0.91; P = 0.03) as strong predictors of survival. An estimated glomerular filtration rate less than 60 ml/min/1.73 m2 portended a threefold risk of mortality.
Conclusions: Our results suggest that specific components of right ventricular dysfunction and renal impairment contribute to increased mortality in SSc-PAH. Understanding the mechanisms of right ventricular dysfunction in response to increased afterload should lead to improved targeted therapy in these patients.