BNP and NT-proBNP in patients with acute myocardial infarction complicated by cardiogenic shock: results from the IABP Shock trial

Introduction

B-type natriuretic peptide (BNP) and N-terminal proBNP (NT-proBNP) are routine diagnostic and monitoring markers in patients with heart failure. LV function and prognosis of these patients have been shown to be reflected by BNP and NT-proBNP levels. However, in patients with cardiogenic shock after myocardial infarction, the relationship and relevance of these markers has not been elucidated.

Methods

The IABP Shock trial was as a monocentric, randomised and prospective clinical trial to determine the role of therapeutic intraaortic balloon pump (IABP) counterpulsation after primary percutaneous transluminal coronary angioplasty (PCI) in acute myocardial infarction (AMI) complicated by cardiogenic shock. Cardiac catheterization was performed in 40 patients within 12 hours of onset of hemodynamic instability. Creatinine, hemodynamic parameters and survival were determined. Further, BNP and NT-proBNP levels were measured on admission as well as 24, 48 and 72 hours afterwards.

Results

BNP levels detected differences in treatment regarding LV-unloading under IABP (632 ± 194 pg/ml vs 1,370 ± 475 pg/ml, P < 0.05). However, there was no significant difference between the group treated with IABP and no IABP with regard to NT-proBNP levels. Interestingly, NT-proBNP levels clearly differentiated between survivors and nonsurvivors (4,590 ± 1,230 pg/ml vs 14,370 ± 4,886 pg/ml, P < 0.05), contrary to no significant difference between survivors and nonsurvivors with regard to BNP levels (NS). Elevated levels of NT-proBNP in patients with cardiogenic shock might be more dependent on impaired renal function, which might reflect additional organ dysfunction (creatinine >200 μmol/l vs creatinine ≤200 μmol/l: 24,965 ± 9,567 pg/ml vs 7,246 ± 2,650 pg/ml, P < 0.05).

Conclusions

In myocardial infarction complicated by cardiogenic shock, levels of BNP and NT-proBNP both provide valuable additional information. BNP seems to closely reflect the cardiac status and effects of therapy, while NT-pro-BNP seems a good indicator for prognosis in patients with cardiogenic shock by its dependency on organ dysfunction.