N-terminal Pro B-type Natriuretic Peptide (Nt-proBNP) Versus Exercise Test for Evaluation of Acute Chest Pain

The investigators' objective is to compare a new strategy combining clinical history and NT-proBNP levels versus the usual care, consisting of early exercise testing, for decision making in patients presenting to the emergency department with acute chest pain, non-diagnostic electrocardiogram and normal troponin. The investigators hypothesised that the new strategy combining clinical risk score and NT-proBNP will reduce the number of hospitalisations without increasing the number of events during the follow-up.

In patients presenting to the emergency department with acute chest pain, the observation of ischemic changes in the electrocardiogram or troponin elevation prompts hospitalisation and, generally, invasive management. However, decision on admission or discharge is uncertain in the remaining patients. The spectrum of these patients spans from individuals without coronary artery disease to some with high risk unstable angina. An early exercise test is usually performed with the aim of guiding the decision. However, the exercise test is not available 24 hours per day/ 7 days per week, around 40% of the patients show contraindication to exercise and there are inconclusive as well as false-positive results. The limitations of the exercise test can lead to unnecessary hospitalisations. Therefore, there is room for alternative tools. Our objective was to compare a new strategy combining clinical history and NT-proBNP levels versus the usual care, consisting of early exercise testing, for decision making in these patients.

We will randomly compare a new strategy combining a previously published and validated clinical risk score (number of points according to pain characteristics and risk factors) along with NT-proBNP levels, versus the usual strategy using exercise test, for the management of patients presenting to the emergency department with acute chest pain, without ischemia in the electrocardiogram and with normal troponin. In the new strategy, high risk patients (clinical risk score =\>3 points) as well as low risk patients (clinical risk score \<3 points) but with NT-proBNP \>110 ng/L, will be hospitalised; on the other hand, low risk patients (clinical risk score \<3 points) with NT-proBNP \<110 ng/L will be discharged. In the usual strategy, all patients will be allocated to early exercise test; patients will be hospitalised in case of a positive result, inconclusive result \<7 METS or contraindication to exercise, whereas they will be discharged in case of a negative result or inconclusive result with \>7 METS without ischemia induction. The primary endpoint will be hospitalisation during the index episode and the secondary endpoints 6-12 months death or acute myocardial infarction, and 6-12month death, myocardial infarction, postdischarge revascularization or readmission by unstable angina.

Eligibility Criteria:
Inclusion Criteria:

* Chest pain of possible coronary origin at criterion of cardiology on duty

Exclusion Criteria:

* Chest pain of obvious non-coronary origin.
* Electrocardiogram showing ST-segment deviation (=\>1mm) or T-wave inversion (=\>2mm) or atrial fibrillation.
* Troponin elevation at any determination.
* Heart failure at admission.
* Renal failure (creatinine \> 1.3 mg/gl).
* Extracardiac disease with life expectancy less than 1 year.
* Structural heart disease different to ischemic heart disease.