Limitations
This is an observational single center retrospective study which makes
it susceptible to inherent selection and information biases. However,
the prospective nature of the data collection and the very low rate of
missing data add strength to the internal validity of the study.
Likewise, since all procedures were performed by a single surgeon, bias
from difference in surgical and myocardial protection techniques is
minimized. Importantly, the findings from our study must be interpreted
and compared to previous and future studies in the context of the large
heterogeneity in cardioplegia practice with regard to composition,
temperature, additives and adjuncts for myocardial protection. These
factors are important confounders that must be evaluated when comparing
different studies of cardioplegia. Finally, we reported only short-term
outcomes and weather DNC is associated with any potential long-term
benefits is unknown.