Increased Mortality in Patients With Preoperative and Persistent Postoperative Pulmonary Hypertension Undergoing Mitral Valve Surgery for Mitral Regurgitation: A Cohort Study

Abstract

Background Preoperative pulmonary hypertension (PH) is associated with excess mortality among patients with severe mitral regurgitation undergoing mitral valve surgery (MVS). However, the links between PH phenotype, pulmonary vascular remodeling, and persistent postoperative PH are not well understood. We aimed to describe the associations between components of pulmonary hemodynamics as well as postoperative residual PH with longitudinal mortality in patients with severe mitral regurgitation who received MVS. Methods and Results Patients undergoing MVS for severe mitral regurgitation from 2011 to 2016 were retrospectively identified within our health system (n=488). Mean pulmonary artery pressure and other hemodynamic variables were determined by presurgical right-heart catheterization. Postoperative pulmonary artery systolic pressure was assessed on echocardiogram 42 to 365 days post-MVS. Longitudinal survival over a mean 3.9 years of follow-up was evaluated using Cox proportional hazards modeling to compare survival after adjustment for demographics, surgical characteristics, and comorbidities. Pre-MVS prevalence of PH was high at 85%. After adjustment, each 10-mm Hg increase in preoperative mean pulmonary artery pressure was associated with a 1.38-fold increase in risk of death (95% CI, 1.13-1.68). Elevated preoperative pulmonary vascular resistance, transpulmonary gradient, and right atrial pressure were similarly associated with increased mortality. Among 231 patients with postoperative echocardiogram, evidence of PH on echocardiogram (pulmonary artery systolic pressure ≥35 mm Hg) was associated with increased risk of death (hazard ratio [HR], 2.02 [95% CI, 1.17-3.47]); however, this was no longer statistically significant after adjustment (HR, 1.55 [95% CI, 0.85-2.85]). Conclusions In patients undergoing MVS for mitral regurgitation, preoperative PH, and postoperative PH were associated with increased mortality.

Keywords: mitral regurgitation; mitral valve surgery; mortality; pulmonary hypertension.

Figure 1. Study flow diagram.

*Includes 24 patients with nondiagnostic echocardiograms and 16 patients who died during the eligibility period of 42 to 365 days post‐MVS and did not have a postoperative echocardiogram. ECMO indicates extracorporeal membrane oxygenation; MR, mitral regurgitation; MVS, mitral valve surgery; PH, pulmonary hypertension; and RHC, right‐heart catheterization.

Figure 2. Survival after mitral valve surgery for severe mitral regurgitation by pulmonary hypertension status.

Cumulative survival after mitral valve surgery for severe mitral regurgitation by (A and B) mean pulmonary artery pressure (mPAP), (C) pulmonary vascular resistance (PVR), and (D) pulmonary hypertension (PH) phenotype. Phenotypes include no PH, postcapillary PH, precapillary PH, and combined pre‐ and postcapillary PH (combined PPC). The no‐PH category in (D) also includes patients with indeterminate/borderline PH (ie, mPAP 20 to 25 mm Hg, PVR <3 Wood units, and pulmonary capillary wedge pressure ≤15).

Figure 3. Predicted 3‐year survival postoperatively for preoperative hemodynamic parameters.

Survival is predicted at 3 years postoperatively for a hypothetical male patient of cohort average age and body mass index for ranges of (A) mean pulmonary artery pressure, (B) pulmonary vascular resistance, (C) transpulmonary gradient, and (D) right atrial pressure. D, Additionally adjusted for pulmonary capillary wedge pressure and predicted for a wedge of 20 mm Hg. Shaded areas represent 95% confidence intervals.

Figure 4. Survival by postoperative pulmonary hypertension (PH).

Overall survival in people with echocardiographic evidence of (A) postoperative PH and (B) reversibility of preoperative PH. For patients stratified by postoperative PH, stratification can only occur after diagnostic echocardiogram is performed in year 1.