The Informative Value of N-Terminal Pro-type B Natriuretic Peptide in Cardiac Surgical Patients with Hypercreatininemia

Abstract

Objective: to study the informative value of a dramatic increase in the preoperative blood level of the inactive moiety of the precursor of N-terminal pro-type B natriuretic peptide (NT-proBNP) in cardiac surgical patients with hypercreatininemia. Subjects and materials. Twenty-one patients with a preoperative NT-proBNP level of 1000 pg/ml or more, who underwent myocardial revascularization under extracorporeal circulation (ECC), were examined. The patients were divided into groups with normal (up to 120 ^mol/l) (Group 1; n=11) and elevated (Group 2; n=10) creatinine concentrations. The values of circulation were processed after skin incision and at the end of surgery. The clinical features of a perioperative period were analyzed. Results. Creatininemia was 103±3.3 and 183±12.9 ^mol/l in Groups 1 and 2, respectively (p<0.05); NT-proBNP was 1397±139 and 1908±170 pg/ml (p<0.05). EuroSCORE-predicted mortality ran to 9.8±1.6 and 9.1±1.7% (p>0.05). There were no intergroup differences in intraoperative circulatory parameters. The intensity of sympatomimetic therapy after ECC was equal in the identified patient groups and there were either no differences (p>0.05) in the frequency of intra-aortic balloon counterpulsation (18.2 and 10.0%), the length of mechanical ventilation (15±1.5 and 18.7±2.3 hours) and intensive care unit stay (1.8±0.5 and 2.0±0.7 days) in survivors, and inpatient mortality (23.7 and 20.0%) that proved to be substantially higher than the EuroSCORE-predicted one. Regression analysis showed that in the entire group of operated patients, the level of NT-proBNP turned out to be a more significant predictor of inpatient mortality (p=0.012) than EuroSCORE-predicted one (p = 0.04). The similar regularity was characteristic for patients with hypercreatininemia. In the patients with hypercholesterolemia, the EuroSCORE-predicted mortality completely lost its significance (p=0.61) in predicting actual mortality rates. In this group, NT-proBNP showed a predicting trend. Conclusion. The blood NT-proBNP concentration of 1000 pg/ml or more preserves its significance as a high operative risk factor in the presence of myocardial revascularization under ECC in patients with the blood creatinine level of 140—270 ^mol/l. Key words: N-terminal pro-type B natriuretic peptide (NT-proBNP), myocardial revascularization, extracorporeal circulation, hypercreatininemia.