Prognostic Value of Acute Vasoreactivity in Chronic Thromboembolic Pulmonary Hypertension

Vasoreactivity, which refers to the reduction of mean pulmonary arterial pressure in response to inhaled vasodilators, is a well-established metric for prognostication and treatment selection in patients with pulmonary arterial hypertension. However, the role of vasoreactivity in chronic thromboembolic pulmonary hypertension is less studied. We investigated whether vasoreactivity at time of diagnosis carries prognostic value in all patients with chronic thromboembolic pulmonary hypertension, and how it relates to the effect of long-term pulmonary vasodilator treatments. Patients diagnosed with CTEPH were prospectively subjected to 40 ppm inhaled nitric oxide testing at the diagnostic right heart catheterization. Classic (acute decrease of mean pulmonary arterial pressure > 10 mmHg to a level below 40 mmHg, n = 25), absolute (acute decrease of by 10 mmHg, n = 47) and percent (acute decrease by 10%, n = 129, all with maintained cardiac output) definitions of vasoreactivity were examined in retrospect. The relationship between each definition and transplantation-free survival was assessed with Cox regression models adjusted for baseline mPAP, age, sex, and WHO functional class. Patients (n = 325) were observed over a median of 5.5 years (interquartile range 2.6-9.2). Vasoreactivity, by the percent definition, was associated with significantly improved adjusted 5-year transplantation-free survival (hazard ratio = 0.61, 95% confidence interval 0.38-0.97, p = 0.036). Among not operated patients (n = 174, 53.5%), vasodilator PH medications were associated with improved survival in vasoresponders (hazard ratio = 0.46, 95% confidence interval 0.22-0.96, p = 0.04), but had no impact on survival in non-vasoresponders (hazard ratio = 0.67, 95% confidence interval 0.36-1.24, p = 0.20). Vasoreactivity at baseline catheterization carries prognostic value in CTEPH.