Correlates and Prognostic Value of NT-proBNP in Post-Acute Coronary Syndrome Patients with Preserved Left Ventricular Ejection Fraction

Background: Patients with Acute Coronary Syndrome (ACS) with preserved Left Ventricular Ejection Fraction (LVEF) have an incidence of adverse outcomes despite the previously presumed benign prognosis. Objective: We hypothesized that NT-pro-BNP could help refine the risk stratification of these patients. Methods: In this observational retrospective study, laboratory and clinical data were collected from 232 consecutive patients with ACS and preserved LVEF (> 50%) and no previous history of Heart Failure (HF) at hospital discharge. Associations between NT-proBNP and the composite outcome of HF hospitalization, HF diagnosis de novo, and all-cause mortality were assessed by univariate and multivariable Cox models. Statistical analyses were performed using Stata software, version 12.1 and a two-sided P-value < 0.05 was considered to be statistically significant. Results: The NT-proBNP median was 408 [IQR 177-853] pg/mL. Patients with increased NT-proBNP were older and were more likely to be female (P = 0.013), be non-smoker (P = 0.039), have worse renal function (P < 0.001), and have lower hemoglobin concentration (P < 0.001). They had more ST-Elevation Myocardial Infarction (STEMI) and evolved with higher Killip classes (P < 0.001). Increased NT-proBNP levels were also associated with higher peak values of Creatinine Kinase (CK) and troponin (r= 0.36, P < 0.001 and r = 0.37, P < 0.001), higher left ventricular mass (P = 0.021), larger left atria (P = 0.013), and higher prevalence of regional LV hypocontractility (P = 0.012 to P = 0.090). During the 4.2 [2.1-5.4] years of follow-up, the composite outcome occurred in 19 patients. After adjusting for age, sex, and Killip class, NT-proBNP was not associated with the composite outcome (HR = 1.18; 95% CI: 0.78 - 1.78). Conclusion: Post-ACS patients with preserved LVEF and increased levels of NT-proBNP were older, had more comorbidities, and presented with a more severe myocardial infarction. However, NT-proBNP levels measured during ACS hospitalization did not predict the clinical adverse outcomes.