Abstract 16517: Atrial Natriuretic Peptide as a Marker for Early Rule-Out of Acute Myocardial Infarction

Abstract

Introduction: Mid-regional pro-ANP is mainly synthesized in the atria of the heart and it′s secretion is stimulated by ischemia and distension of the myocardium. Objective: To assess the utility of ANP for rule out NSTEMI in combination with cardiac troponin in unselected patients who attend the Emergency Department (ED) with acute cardiac chief complaints. Methods: Patients with chest pain and dyspnea were enrolled over a period of 30 months in the Emergency Department (n=537). Patients with STEMI were excluded from the analysis as diagnosis is ECG- and not biomarker-based (n=18). Blood samples were drawn within 2 hours after admission. Gold-Standard diagnoses were adjudicated by an independent cardiologist. ANP was measured using the BRAHMS Kryptor MR-proANP assay. The lower limit of detection is 2.1 pmol/l. The 97.5 th percentile of a normal population is 86.2 pmol/l and was applied as a cut-off value in this analysis. Troponin I was measured using the Stratus CS and a cut-off value of 0.1 μg/L was applied. Variables are shown as median (IQR) and 95%-CIs. Results: The median ANP-value in all patients (n=519) was 135 pmol/l. Patients with NSTEMI (n=58) had significantly higher ANP-values (244/104-350 pmol/l) as compared to patients with other diagnoses (126/74-256; p<0.0001). In ROC-analysis ANP had an area under the curve of 0.648 (CI:0.582-0.715) for the diagnosis of NSTEMI. Of all patients, 74.2% were troponin negative at admission (n=385). Of these patients, 32.2% (n=124) were also ANP negative. The prevalence of AMI in this subgroup was 1.6% (n=2). The NPV for the combination of troponin and ANP was 98.4% (CI: 94.3-99.8%) and thus higher than for both markers alone (figure 1). In combination with Copeptin, the NPV increased to 100% (CI: 96.3-100%). Conclusions: ANP has potential for early rule-out of AMI in combination with troponin and, due to a different pathophysiological stimulus, it might be used as part of a triple-marker strategy with copeptin and troponin.