Little is known about the safety and clinical utility of retrograde autologous priming (RAP) in patients undergoing minimally invasive mitral valve surgery. We hypothesized that RAP would increase the oxygen delivery index (DO2i) while decreasing red blood cells transfusion requirements compared to valve surgery without RAP.

The study was an observational analysis.

Single institutional study.

We analyzed data from 500 consecutive patients who underwent minimally invasive isolated mitral valve repair from December 31, 2012 to December 31, 2019.

RAP was performed in 235 patients (47%) prior to the initiation of cardiopulmonary bypass (CPB).

A continuous monitoring system was used for DO2 management during CPB. Mean arterial pressure was maintained between 55 and 70 mmHg and cardiac index was set at 2.4 L/min/m² with adjustments in accordance with DO2i. The trigger point for red cell blood transfusion during CPB was hemoglobin <7 g/dL.

Baseline hematocrit was lower in the RAP group compared to the no-RAP group (33.4±3.6 vs. 38.1±4.9, respectively; p<0.001). Both CPB and cross clamp times were similar between groups. Hematocrit during CPB was significantly higher in the RAP group compared to the no-RAP group (27.6±2.6 vs 25.9±5.1, respectively; p<0.001). RAP was also associated with significantly higher mean DO2i (292±19.5 vs. 282.9±35.1 mL/min/m², respectively; p<0.001) and fewer red blood cells transfusions during the intraoperative and immediate post-operative periods (p<0.001).

In a minimally invasive mitral valve context, RAP was safe and associated with better DO2i, higher hematocrit, and fewer intra- and post-operative red blood cells transfusions.