Pulmonary-Systemic Pressure Ratio Correlates with Morbidity in Cardiac Valve Surgery

Abstract

Objectives: Pulmonary hypertension portends worse outcomes in cardiac valve surgery; however, isolated pulmonary artery pressures may not reflect patients' global cardiac function accurately. To better account for the interventricular relationship, the authors hypothesized that patients with greater pulmonary-systemic ratios (mean pulmonary arterial pressure)/(mean systemic arterial pressure) would correlate with worse outcomes after valve surgery.

Design: Retrospective cohort study.

Setting: Single academic hospital.

Participants: The study comprised 314 patients undergoing valve surgery with or without coronary artery bypass grafting (2004-2016) with Society of Thoracic Surgeons predicted risk scores and preoperative right heart catheterization.

Interventions: None.

Measurements and main results: The pulmonary-systemic ratio was calculated as follows: mean pulmonary arterial pressure/mean systemic arterial pressure. Patients were stratified by pulmonary-systemic ratio quartile. Logistic regression was used to assess the risk-adjusted association between pulmonary-systemic ratio or mean pulmonary arterial pressure. Median pulmonary-systemic ratio was 0.33 (Q1-Q3: 0.23-0.65); median pulmonary arterial pressure was 29 (21-30) mmHg. Patients with the highest pulmonary-systemic ratio had the highest rates of morbidity and mortality (p < 0.0001). A high pulmonary-systemic ratio was associated with longer duration in the intensive care unit (p < 0.0001) and hospital (p < 0.0001). After risk-adjustment, pulmonary-systemic ratio and pulmonary arterial pressure were independently associated with morbidity and mortality, but the pulmonary-systemic ratio (odds ratio 23.88, p = 0.008, Wald 7.1) was more strongly associated than the pulmonary arterial pressure (odds ratio 1.035, p = 0.011, Wald 6.5).

Conclusions: The pulmonary-systemic ratio is more strongly associated with risk-adjusted morbidity and mortality in valve surgery than pulmonary arterial pressure. By integrating ventricular interactions, this metric may better characterize the risk of valve surgery.

Keywords: cardiac catheterization/intervention; cardiac function, physiology; pulmonary vascular resistance/hypertension.