Outcome of Unilateral Pulmonary Edema after Minimal-Invasive Mitral Valve Surgery: 10-Year Follow-Up

Abstract

The study was approved by the institutional review board (IRB) at the University Medical Center Campus Kiel, Kiel, Germany (reference number: AZ D 559/18) and registered at the German Clinical Trials Register (reference number: DRKS00022222).

Objective: Unilateral pulmonary edema (UPE) is a complication after minimally invasive mitral valve surgery (MIMVS). We analyzed the impact of this complication on the short- and long-term outcome over a 10-year period.

Methods: We retrospectively observed 393 MIMVS patients between 01/2009 and 12/2019. The primary endpoint was a radiographically and clinically defined UPE within the first postoperative 24 h, secondary endpoints were 30-day and long-term mortality and the percentage of patients requiring ECLS. Risk factors for UPE incidence were evaluated by logistic regression, and risk factors for mortality in the follow-up period were assessed by Cox regression.

Results: Median EuroSCORE II reached 0.98% in the complete MIMVS group. Combined 30-day and in-hospital mortality after MIMVS was 2.0% with a 95, 93 and 77% survival rate after 1, 3 and 10 years. Seventy-two (18.3%) of 393 patients developed a UPE 24 h after surgery. Six patients (8.3%) with UPE required an extracorporeal life-support system. Logistic regression analysis identified a higher creatinine level, a worse LV function, pulmonary hypertension, intraoperative transfusion and a longer aortic clamp time as predictors for UPE. Combined in hospital mortality and 30-day mortality was slightly but not significantly higher in the UPE group (4.2 vs. 1.6%; p = 0.17). Predictors for mortality during follow-up were age ≥ 70 years, impaired RVF, COPD, drainage loss ≥ 800 mL and length of ventilation ≥ 48 h. During a median follow-up of 4.6 years, comparable survival between UPE and non-UPE patients was seen in our analysis after 5 years (89 vs. 88%; p = 0.98).

Conclusions: In-hospital outcome with UPE after MIMVS was not significantly worse compared to non-UPE patients, and no differences were observed in the long-term follow-up. However, prolonged aortic clamp time, worse renal and left ventricular function, pulmonary hypertension and transfusion are associated with UPE.

Keywords: ECLS; ECMO; UPE; minimally invasive; mitral valve surgery; unilateral lung edema.

Figure 1

Two chest X-rays at admission to intensive-care-unit after minimal-invasive mitral-valve surgery. (a) chest X-ray showing normal lung tissue (no unilateral lung edema), with a chest tube and a central venous line in the upper vena cava. (b) chest X-ray of a patient with right sided unilateral pulmonary edema (UPE), i.e., more than 20% opafication of the right hemithorax and a chest tube and a central venous line in place.

Figure 2

UPE per year (% of MIMVS). UPE, unilateral pulmonary edema; MIMVS, minimal-invasive mitral valve surgery.

Figure 3

Creatinine levels in the non-UPE and the UPE groups. UPE, unilateral-pulmonary-edema; one outlier (non-UPE, 7.6 mg/dL) was excluded for the graphical representation. ◦ outlier; * extreme outlier.

Figure 4

Duration of surgery, cardiopulmonary bypass (CPB) time and aortic clamp time in the non-UPE and the UPE groups. UPE, unilateral pulmonary edema; three outliers (duration of surgery, non-UPE, 590–1139 min) were excluded for the graphical representation, ◦ outlier; * extreme outlier.

Figure 5

Kaplan-Maier long-term survival curves of the analyzed subgroups. (A) Survival curve of the MIMVS patients. (B) Survival curves of the UPE group and the non-UPE group. (C) Survival curves of patients requiring ECLS vs. non-ECLS within the UPE group. N, number; MIMVS, minimal-invasive mitral valve surgery; CI, confidence interval; UPE, unilateral pulmonary edema; ECLS, extracorporeal life support; ECMO extracorporeal membrane oxygenation.

Figure 6

shematic overview of the study: Long-term outcomes of unilateral pulmonary edema after minimally invasive mitral 325 valve surgery: a 10-year follow-up.