eComment: Individualization of blood cardioplegia administration mode Free

Reading your interesting article with its provocative title [1], there is a high risk of misunderstanding concerning myocardial protection. Indeed, both your title and abstract give the impression that a single shot of Calafiore warm blood cardioplegic solution [2] ensures the achievement of adequate myocardial protection for >20 min. This fact is opposed to both current experimental and clinical data that suggest that warm blood cardioplegia could be interrupted no >10 min [3] or 15 min [4], respectively, without the equivalent critical reduction of myocardial energy supply and pH disorders [3]. Examining carefully your retrospective study, we realize that it is not in accordance with the above data. Simultaneously, your article raises several questions:

1. Is your study really non-randomized as you mention that ‘the use of a single-shot or multi-shot cardioplegia was solely based on surgeons’ preferences'? Therefore, the population in which you performed single-shot cardioplegia included patients in low risk for peri-operative cardiovascular events. As a consequence, your conclusion that ‘the incidence of postoperative infarction was significantly in favour of single-shot cardioplegia’ has no value.

2. There is no comparison between the two groups as far as CPB time and myocardial enzymes or other markers of myocardial damage are concerned.

3. Also, from your results the supremacy of repeated blood cardioplegia is evident as you conclude that there is ‘a weak statistical significance of cardioplegia in favour of repeated administration’.

4. As CPB time was a significant risk factor concerning the need of intraaortic balloon pump (IABP), how could you explain the fact that CPB time does not affect the peri-operative need of inotropics?

5. In addition, how could the fact that the postoperative need of inotropics was independent of the cardioplegia administration method (single or repeated doses of cardioplegia) be interpreted while simultaneously the need of inotropics had a statistically significant relation with the operative time?

6. Why was the frequency of postoperative renal failure in favour of repeated administration of blood cardioplegia, while there was no negative effect of single-dose cardioplegia concerning the need either of IABP or inotropics? Where else could you attribute the postoperative need of dialysis except to the above factors? In our opinion, each patient has a different threshold of CPB time, dependent on either pre-operative factors such as collaterals, intercoronary relationship, proximal stenoses, left main CAD, hypertrophy, or peri-operative factors such as temperature, sequence of anastomoses, mode of cardioplegia perfusion, mode of venting, etc. Consequently, the performance of a stereotypic method of myocardial protection in all patients will result in inevitable consequences in patients that exceed their corresponding ‘affordable threshold of CPB time’.

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