Clinical significance of dynamic pulmonary vascular resistance in two populations at risk of pulmonary arterial hypertension.

peer reviewedAIMS: Patients at risk of pulmonary arterial hypertension (PAH) may present with abnormal dynamic pulmonary vascular resistance (PVR) during exercise. However, its clinical significance remains unclear. The present study aimed at analysing the meaning of dynamic PVR in two populations at risk of PAH: secundum atrial septal defect (ASD) and systemic sclerosis (SSc). METHODS AND RESULTS: Adult patients with corrected ASD were consecutively selected from the database of Pediatric and Congenital Heart Disease of the University Hospitals Leuven. Patients with SSc were consecutively selected from the rheumatology database of the University Hospital Liege. At inclusion, all underwent a rest and bicycle stress echocardiography to obtain baseline right heart characteristics and dynamic PVR. Routine follow-up echocardiography was performed. Twenty-eight patients with corrected ASD (mean age 41 +/- 17 years, 79% female) were followed for a median time of 3.7 [inter-quartile range (IQR) 2.9-4.1] years. No patient developed PAH. Dynamic PVR was significantly associated with right atrial dilatation at latest follow-up (Spearman's rho 0.51, P = 0.013). Forty-five SSc patients (mean age 54 +/- 13 years, 76% female) were followed for a median time of 2.4 (IQR 0.8-2.9) years. Thirteen patients (30%) developed PAH. Dynamic PVR was the only independent predictor of PAH (hazards ratio 1.22, 95% confidence interval 1.01-1.47). No significant right heart morphometric changes occurred. CONCLUSION: Dynamic PVR predicted PAH development in patients with SSc, whereas dynamic PVR was associated with right heart morphometric changes after ASD closure. The predictive role of dynamic PVR might depend on the underlying disease type. Larger studies are needed to confirm this hypothesis