Mitral Regurgitation Grading in the Operating Room: A Systematic Review and Meta-analysis Comparing Preoperative and Intraoperative Assessments During Cardiac Surgery.

OBJECTIVE: To assess differences in mitral regurgitation (MR) grade between the preoperative and the intraoperative evaluations.

DESIGN: Systematic review and meta-analysis of 6 observational studies found from MEDLINE and EMBASE.

SETTING: Cardiac surgery.

PARTICIPANTS: One hundred thirty-seven patients.

INTERVENTION: Comparison between the preoperative MR assessment and the intraoperative evaluation conducted under general anesthesia (GA), with or without "hemodynamic matching" (HM) (artificial increase of afterload).

MEASUREMENTS AND MAIN RESULTS: The primary outcome was the difference between the preoperative and intraoperative MR grade under "GA-only" or "after-HM." Secondary analyses addressed differences according to effective regurgitant orifice area (EROA), regurgitant volume (RVol), color-jet area, and vena contracta width. Risk of MR underestimation was found under "GA-only" (SMD: 0.55; 95% confidence interval [CI], 0.31-0.79, p < 0.00001), but not "after-HM" (SMD: -0.16; 95% CI, -0.46 to 0.13, p = 0.27). Under "GA-only", EROA had a trend toward underestimation (p = 0.07), RVol was reliable (p = 0.17), while reliance on color-jet area and vena contracta width incur risk of underestimation (both p = 0.003). After HM, EROA accurately reflected preoperative MR (p = 0.68) while RVol had a trend toward overestimation (p = 0.05). The overall reported incidence of misdiagnoses was slightly more common under "GA-only" (mean 48%, 39% underestimation, 9% overestimation; range: 32%-57%) than "after-HM" (mean 41%, 12% underestimation, 29% overestimation; range: 33%-50%). Only the minority of misdiagnoses were clinically relevant: underestimation was around 10% (both approaches), but 18% had clinically significant overestimation "after-HM" as compared with 3% under GA-only.

CONCLUSIONS: Intraoperative assessment under "GA-only" significantly underestimated MR. A more accurate intraoperative evaluation can be obtained with afterload manipulation, although HM strategy carries high risk of clinically significant overestimation.