RESUMO
Background: Myocardial protection is crucial for successful cardiac surgery, as it prevents heart muscle damage that can occur during the procedure. Prolonged hypoxia without proper protection can lead to adenosine triphosphate consumption, microvilli loss, blister formation, and edema. Custodiol, del Nido, and modified del Nido are single-dose cardioplegic solutions with proven safety and significance in modern surgery. While each has been independently assessed for patient outcomes, limited research directly compares them. This study aims to compare their myocardial protection using histological analysis. Methods: In a double-blind clinical trial, at least 90 patients will be randomly assigned to receive one of the three cardioplegic solutions. Myocardial biopsies will be collected before cardiopulmonary bypass and 15 minutes after reperfusion. The surgical, anesthetic and perfusion techniques will be the same for all patients, following the Institution's standard protocols. Discussion: The ideal cardioplegic solution does not exist, and its selection remains challenging for surgeons. In modern surgical practice, understanding the behavior of these solutions and the ischemic tissue damage caused during induced cardiac arrest allows for safer surgical procedures. The results of this clinical trial can help in understanding the behavior of cardioplegic solutions and their tissue effects. Thus, by selecting the best cardioplegic solution, ischemic damage can be minimized, enhancing the effectiveness of this essential technique in cardiac procedures. The study may aid in implementing clinical protocols in several institutions, aiming to choose the solution with a superior myocardial protection profile, increasing safety, and reducing expenses. Trial Registration: Brazilian Clinical Trials Registry (ReBEC, http://ensaiosclinicos.gov.br/): RBR-997tqhh. Registered: January 26th, 2022.