Do we correctly calculate doses of cardioplegia during aortic valve replacement procedures? A preliminary report

Introduction
Intraoperative myocardial protection during aortic valve replacement (AVR) for aortic stenosis (AS) is of paramount importance for outcomes. The dose of cardioplegia is usually calculated with reference to body mass.

Aim
The aim of this study was to assess whether such a strategy should be applied to all AS patients undergoing AVR.

Material and methods
The study included 94 patients who underwent elective isolated AVR in cardiopulmonary bypass with cold cardioplegic arrest, with a mean age of 65.4 ±7.8 years. They were divided into two subgroup: A with an infusion of high (above median) and subgroup B with a low (below median) volume of cardioplegia indexed for left ventricular mass (LVM). Their doses were referred to the maximal postoperative release of cardiac troponin I (cTnI max). Eventually, it was examined whether the extent of intraoperative myocardial injury translated into long-term survival stratified according to the Kaplan-Meier method.

Results
The mean volume of cardioplegia was 1381 ±279 ml (4.9 ±1.6 ml/g of LV myocardium). cTnI max was much higher in group A than in group B (medians: 14.918 vs. 9.876 µg/l; p = 0.005). Moreover, a negative correlation between the index cardioplegia volume and cTnI max (r = 0.345) was noted. The five-year probability of survival in subgroup A (95.7%) was significantly better than that in subgroup B individuals (82.6%, p = 0.044).

Conclusions
Calculating cardioplegic doses during AVR solely based on body mass may be suboptimal and have a significant impact on postoperative outcomes.