N-terminal pro-B type natriuretic peptide as a predictor for myocardial preservation in cases of isolated severe Aortic stenosis

Background
Myocardial hypertrophy is a common pathologic finding in the natural history of severe aortic stenosis. A hypertrophied myocardium predisposes the patient to decreased tolerance to ischemia and increased reperfusion injury, myocardial protection is of utmost importance in patients undergoing aortic valve replacement (AVR) for severe aortic valve stenosis. Myocardial protection techniques during cardiac arrest have been extensively investigated in the clinical setting of coronary revascularization. However, fewer studies have been carried out on patients affected by left ventricular (LV) hypertrophy, where the choice of type, and temperature of cardioplegia remains controversial.
Aim
The study investigates preoperative N-terminal pro-B type natriuretic peptide (NT pro-BNP), its relation to Troponin I levels, and whether it can predict a preferred cardioplegic solution by comparing the short-term outcomes of the two commonly used blood and Histidine-Tryptophan-Ketoglutarate (HTK) cardioplegic solutions in patients undergoing aortic valve replacement for severe aortic stenosis.
Patients and methods
A total of 72 patients will be randomly allocated into two groups; group (A=36) received HTK solution, and group (B=36) received blood cardioplegia. All anesthesia protocols are unified among all patients. All surgical procedures were conducted on a cardioplegic arrested heart via standard median sternotomy, utilizing full Cardiopulmonary bypass (CPB) via aorto-atrial cannulation and LV venting through a left atrial catheter under moderate hypothermia (28–32°C) by topical cooling.
Results
There was no statistically significant difference found between group A and group B regarding post-operative ejection fraction (EF) and newly developed postoperative Regional wall motion abnormalities (RWMA). There was no statistically significant difference found between group A and group B regarding the percentage of patients with atrial fibrillation, ventilation hours, and exploration while there was a statistically significant increase in troponin, I level in group B than group A. There was a statistically significant negative correlation between NT pro-BNP preoperative and aortic valve area (AVA) and also with ejection fraction preoperative while there was a statistically significant positive correlation found between NT pro-BNP and troponin I preoperative and postoperative.
Conclusion
HTK solution and Blood cardioplegia both offer sufficient protection for the myocardium. NT pro-BNP serves as a sensitive indicator for predicting the results and effectiveness of different cardioplegia types