Midregional pro-A-type natriuretic peptide as part of a dual biomarker strategy for the early rule out of non-ST segment elevation acute coronary syndrome - The WilCop study.

BACKGROUND: Mr-proANP is a biomarker produced in atrial and left ventricular myocardium. We investigated the effect of combined measurement of mr-proANP and high-sensitive cardiac Troponin I assay of the penultimate generation (s-cTnI) for an early type-1 and type-2 NSTE-ACS rule-out with emphasis on the very early presenters' subgroup with symptom onset time (SOT) ≤ 2 h.

METHODS: This was a prospective cohort study of 311 consecutive patients admitted to ER with symptoms suggestive of an acute coronary syndrome (ACS). All patients had baseline mr-proANP and s-cTnI measurements.

RESULTS: Of the total cohort, 17.6% (n = 55) had final diagnosis of NSTE-ACS: 9.6% (n = 30) had an angiographically-confirmed type-1 infarction and 8.0% (n = 25) had type-2 infarction. In the subgroup of very early presenters (SOT ≤ 2 h) the negative predictive value (NPV) of s-cTnI for type-1 NSTE-ACS was 96.7% (95%-CI: 87.5-99.4) and the NPV of mr-proANP was 100% (95%-CI: 87.1-100). The dual biomarker strategy yielded an NPV of 100% (95%-CI: 86.7-100). In the same time-related subgroup, the NPV of s-cTnI alone for type-2 was 98.3% (95%-CI: 89.8-99.9) and the NPV of mr-proANP was 97.0% (95%-CI: 82.5-100). The combination of biomarker increased the NPV to 100% (95%-CI: 86.7-100).

CONCLUSIONS: Our study demonstrated an immediate release pattern of mr-proANP in NSTE-ACS that may bridge the silent troponin time phenomenon when highest-sensitivity cardiac troponin assays are not used. This concept performed best in the very early presenters' subgroup with an excellent NPV of 100% and might result in an early rule-out of NSTE-ACS thus accelerating the diagnostic work-up.