Mortality-Related Risk Factors in Patients with Pulmonary Arterial Hypertension and Chronic Thromboembolic Pulmonary Hypertension. The Importance of Response to Treatment

Background: Pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH) are serious diseases with similar pathophysiologic aspects. The prognosis of patients with these conditions is highly uncertain, particularly incident cases. Methods: A Cox proportional hazards model was applied to a group of 85 patients (81% women, mean age 52 (18 82) years) with PAH (80%) and non-surgical CTEPH (20%) to evaluate risk factors for mortality. The following variables were included in the model: age, etiology, baseline 6-minute walk test (6 mWT), cardiac index, and improvement in the 6 mWT following initiation of first medical treatment. Results: In the multivariate analysis, the response to treatment, assessed by an improvement on the 6 mWT, was the most relevant prognostic factor in these patients (RR, 4.832 (95% CI, 1.888 12.364); p = 0.001). The remaining variables studied in this model had less influence on the prognosis: age > 50 years (RR, 0.744 (95% CI, 0.26 2.133); p = 0.582); etiology of connective tissue disease-associated PAH (RR, 3.145 (95% CI, 0.995 9.946); p = 0.051) or CTEPH (RR, 0.654 (95% CI, 0.179 2.387); p = 0.521) with respect to idiopathic PAH; baseline 6 mWT (RR, 1.173 (95% CI, 0.599 4.895); p = 0.315); or cardiac index (RR, 2.295 (95% CI, 0.793 6.642); p = 0.125). Conclusions: There is a high degree of uncertainty regarding the prognosis of PAH and CTEPH at the start of appropriate treatment. Our results support the idea that the initial treatment response is of paramount importance as prognostic factor in these patients.