Pulmonary arterial pulse pressure and mortality in pulmonary arterial hypertension

In the Framingham studies, systemic arterial pulse pressure correlated linearly with morbidity and mortality. Right ventricular (RV) systolic dysfunction and pulmonary circulation stiffening result in abnormalities of pulmonary arterial (PA) pulse pressure in PA hypertension (PAH). We investigated the prognostic potential of PA pulse pressure in 67 patients with PAH diagnosed between January 1996 and March 2004 (33 idiopathic PAH, 34 PAH-connective tissue disease). The population was arbitrarily divided into tertiles of PA pulse pressure (= systolic-diastolic PA pressure) and 5-year mortality was assessed using the Kaplan-Meier method. The extent of RV systolic dysfunction and pulmonary circulation stiffening within each tertile was assessed by comparing the mean cardiac index and alpha (a recently described measure of pulmonary circulation distensibility) in each. Independent predictors of mortality were identified by Cox regression. Five-year mortality rates in patients with low, intermediate and high pulse pressures were 40%, 91% and 54%, respectively. Pulse pressure did not independently predict mortality, but cardiac index, 6-min walk test distance and mixed venous oxygen saturation did. Pulse pressure correlated with circulation stiffening (alpha) but did not correlate with cardiac index which tended to be lower in patients with intermediate pulse pressure and high mortality. PA pulse pressure correlated with pulmonary circulation stiffening but did not predict mortality in this study. RV dysfunction provided better prognostic information and probably explains the higher mortality seen in patients with intermediate pulse pressure.