The Significance of the Cardiac Peptide NT-proBNP in the Assessment of Risk for Myocardial Revascularization in Patients with Decreased Left Ventricular Ejection Fraction

Abstract

Objective: to substantiate a procedure for predicting the severity of postperfusion acute heart failure (AHF) from the baseline level of NT-proBNP during myocardial revascularization in patients with a left ventricular ejection fraction (LVEF) of less than 35%. Subjects and materials. Fifty-six patients with a LVEF of less than 35% were examined. A total of 3.5±0.1 (range 2—4) coronary arteries were shunted under cardio-pulmonary bypass (CPB) (71.0±5.5 min). The concentration of NT-proBNP was measured before surgery (Cardiac Reader®, Roche). Mortality rates, sympathomimetic agents’ dosages required after EC, and the frequency of use of intraaortic balloon pumping (IABP) were analyzed. Results. A good clinical course was observed in 47 cases (Group 1). AHF was recorded in 9 patients (Group 2). Comparative analysis demonstrated that the preoperative concentration of NT-proBNP (871±111 pg/ml in Group 1 and 1946±236 pg/ml in Group 2) was of the highest prognostic value as compared with the traditional indicators (p=0.0015). Patients with a NT-proBNP concentration of less than 600 pg/ml did not virtually need inotropic therapy after EC. In a group with a biomarker level of 600—1200 mg/ml, the infusion of dopamine and dobutamine achieved the traditional cardiotonic dosages and every three patients needed epinephrine. With NT-proBNP of 1200-2000 pg/ml, mortality from AHF was 15.4%; a need for epinephrine and IABC was 46.4 and 7.7%, respectively. The peptide concentration of more than 2000 pg/ml indicated the extremely high risk of severe AHF. In the postperfusion period, each patient was given epinephrine and an IABC system was installed in half of them. In this group mortality achieved 50%. Conclusion. It is expedient to determine a preoperative NT-proBNP concentration in a LVEF of less than 35% to predict AHF to be occurred after myocardial revascularization. The concentration of less than 1200 pg/ml may be considered to be a safe level of the peptide. Its content increase more than 2000 pg/ml suggests that there is an extremely high risk of severe AHF. The level of this biomarker may be a guide to choose an anesthetic tactic. Key words: NT-proBNP, cardiosurgery, heart failure.