Exercise Pulmonary Resistances Predict Long-Term Survival in Systemic Sclerosis

Abstract

Background: Pulmonary hemodynamics during exercise may reveal early pulmonary vascular disease and may be of clinical and prognostic relevance in systemic sclerosis (SSc). We aimed to assess the prognostic relevance of exercise pulmonary resistances in patients with SSc with no or mildly increased mean pulmonary arterial pressure (mPAP).

Research question: Are pulmonary resistances at peak exercise independent predictors of mortality in systemic sclerosis?

Study design and methods: All SSc patients with resting mPAP < 25 mm Hg and at least one year of follow-up data who underwent symptom-limited exercise right heart catheterization between April 2005 and December 2018 were analyzed retrospectively. Age-adjusted Cox regression analysis was used to evaluate the association between pulmonary resistances and all-cause mortality.

Results: The cohort consisted of 80 patients: 73 women and 7 men with a mean age of 57 years (interquartile range [IQR], 47-67 years) and a mean follow-up time of 10.4 years (IQR, 8.5-11.8 years). At baseline, resting mPAP of ≤ 20 mm Hg and 21 to 24 mm Hg was found in 68 and 12 patients, respectively. Pulmonary vascular resistance (PVR) and total pulmonary resistance (TPR) at peak exercise were associated significantly with mortality (P = .006 [hazard ratio (HR), 2.20; 95% CI, 1.26-3.87] and P = .026 [HR, 1.56; 95% CI, 1.06-2.29]), whereas resting PVR and TPR were not (P = .087 [HR, 2.27; 95% CI, 0.89-5.83] and P = .079 [HR, 1.88; 95% CI, 0.93-3.80]). The mPAP per cardiac output (CO) and transpulmonary gradient (TPG) per CO slopes were associated significantly with mortality (P = .047 [HR, 1.14; 95% CI, 1.002-1.286] and P = .034 [HR, 1.34; 95% CI, 1.02-1.76]) as well. The area under the receiver operating characteristic curve for exercise PVR to predict 10-year mortality was 0.917 (95% CI, 0.797-1.000).

Interpretation: PVR and TPR at peak exercise, mPAP/CO slope, and TPG/CO slope are predictors of age-adjusted long-term mortality in SSc patients with no or mildly increased pulmonary arterial pressure.

Keywords: exercise hemodynamics; outcome; pulmonary vascular resistance; right heart catheterization; systemic sclerosis.