Background: It was previously demonstrated that in adults with congenital heart disease and pulmonary arterial hypertension and/or the Eisenmenger syndrome, the pulmonary circulation remained responsive to inhaled nitric oxide (iNO). We wanted to evaluate whether the responsiveness to iNO was related to mid-term outcome in these patients.
Methods: In 21 consecutive patients, total pulmonary vascular resistance (TPR) was measured at baseline, after 5 min iNO (80 ppm), and after NO withdrawal. Patients were considered responders when TPR was reduced by at least 20% during NO inhalation or when TPR increased by more than 10% after NO withdrawal. Responders and non-responders were followed prospectively and the primary endpoint of the study was cardiopulmonary death, the secondary endpoint the combination of death, need for treatment with prostacyclin or heart-lung transplantation. Kaplan-Meier survival curves for both groups were plotted and compared using log rank testing.
Results: Ten patients were considered responders (four male, median age 25 years, Q1 19 and Q3 66 years), while 11 patients did not respond (two male, median age 27 years, Q1 18 and Q3 40 years). The median follow-up time of the total group was 5.0 years (Q1 3.2 and Q3 5.7 years). Four of the non-responders died a cardiovascular death; none of the responders died. The difference in survival between responders and non-responders was statistically significant. For the secondary endpoint, no significant differences were found between both groups.
Conclusions: The responsiveness to inhaled NO in adult patients with pulmonary arterial hypertension and/or the Eisenmenger syndrome is related to mid-term outcome. These findings might be important for risk stratification and the choice of treatment in this specific patient population.