Outcome stratification of patients with impaired renal functions after isolated prosthetic mitral valve replacement

Objectives: Patients with impaired renal functions have a variable risk of morbidity and mortality in cardiovascular surgery. Poor outcome was reported among patients who underwent valve surgery. Current study is presumed to compare the early outcomes of patients having different degrees of impaired renal functions and undergoing mitral valve replacement surgery.

Methods: 135 patients were admitted into the three highly specialized centers in Cairo and Ismailia–Egypt between Dec.2018 and Jan.2020 Preoperative, intraoperative and early post-operative data were recorded. Impairment may present as one of these strata: early reversible (G1-2 included strata 1 & 2 kidney disease patients), moderate G3-4 included strata 3 & 4 kidney disease patients) or advanced irreversible renal damage. (The 5th stratum or G5-KD included end stage renal disease patients undergoing 4-hour hemodialysis sessions, three times a week, with bicarbonate dialysate). We correlated outcome among each stratum with cardiac and renal functions in that stratum.

Results: The more is the impairment of renal functions at any peri- operative stage, the longer is the need for prolonged mechanical ventilation and the longer is the hospital stay. We found that levels of serum creatinine were significantly increased postoperatively Also, the more is the reversibility of the renal impairment, even by renal dialysis, the much better is the outcome (P=.0019).  We also found insignificant difference between different strata of irreversible renal impairment in the early outcome of the prosthetic mitral valve replacement surgery. The early reversible damage can be repaired peri-operatively.

Conclusions: Prosthetic mitral valve replacement among patients with different degrees of impaired renal functions is not only feasible but also it does not seem to add any more deterioration into renal function. Prolonged mechanical ventilation and hospital stay are the only drawbacks of irreversibly impaired renal damage by dialysis or renal transplant.