Elevated Pulmonary Artery Pressure, Not Pulmonary Vascular Resistance, is an Independent Predictor of Short-Term Morbidity Following Bidirectional Cavopulmonary Connection

Single ventricle palliation relies on the pulmonary vasculature accommodating non-pulsatile systemic venous return. Mean pulmonary artery pressure (MPAP) and indexed pulmonary vascular resistance (PVRi) are two measures that impact pulmonary blood flow following bidirectional cavopulmonary connection (BCPC). The purpose of the study was to determine which hemodynamic features are associated with adverse outcomes after BCPC. Pre-operative hemodynamic data and post-operative morbidity and mortality in 250 patients undergoing BCPC at a single center from 2008 to 2014 were reviewed. Patients were then separated into 5 physiologic states based on MPAP, PVRi, and degree of pulmonary to systemic blood flow (Q(p):Q(s)). There were 9 (3.6%) deaths, and 49 patients (20%) sustained major morbidity. An ROC curve identified MPAP>16mmHg as an inflection point. Pre-BCPC sildenafil and oxygen use, ventricular dysfunction, and MPAP>16mmHg (OR 4.1 [95% CI 1.8-9.2]) were independently associated with morbidity. MPAP>16mmHg (OR 6.7 [95% CI 1.6-28]) and pre-BCPC oxygen use were associated with hospital mortality. PVRi was not associated with morbidity or mortality. Of the five physiologic states, patients with high MPAP, low PVRi, and low Q(p):Q(s) fared the worst, with the highest risk of major morbidity (OR 8.6 [3.0-24.9]) and highest risk of mortality (OR 8.0 [1.5-41.3]) when compared to their reference groups (low MPAP, low PVRi). Elevated MPAP, need for pre-operative oxygen support, sildenafil use, and systemic ventricular systolic dysfunction predict morbidity following BCPC. Specifically, patients with elevated MPAP not due to elevated PVRi or pulmonary blood flow had the highest risk of morbidity and mortality.