[Suspected acute coronary syndrome in patients without ST-elevation. Exclusion of infarction, early clinical estimation and non-coronary diagnoses]

Abstract

Background and objective: Patients admitted to the hospital with suspected acute coronary syndrome (ACS) represent a collective at high risk. The NOWIS substudy aimed at evaluating 3 points: (1) Safe exclusion of myocardial infarction by history, symptoms, biochemical markers and the ECG, (2) value of the first diagnosis by the physician in the emergency room, and (3) prevalence and distribution of non-coronary leading diagnoses.

Patients and methods: In 164 patients admitted with suspected ACS without ST-segment elevation (73 % men, median age 66 years) the cardiac markers myoglobin, troponin T and CK/CK-MB were assessed on admission and 4 h later. In 2 of the NOWIS centers, the diagnosis on admission, derived from the ECG, history and clinical symptoms, was compared with the leading diagnosis at discharge, based on coronary angiography and, if negative, on additional esophago-gastroscopy.

Results: (1) Myoglobin was the biochemical marker with the highest sensitivity 4 h after admission for acute myocardial infarction (classic) definition by CK-MB elevation) with 90.4 %, followed by troponin T with 84.6 %. Four h after admission, in 15.4 % of the infarction patients (prevalence 31.7 %) troponin T was normal. (2) The admission diagnosis instable angina pectoris was confirmed in 46.7 % (57 of 122), suspected acute infarction in 76.2 % (32 of 42). On the other hand, 90.4 % (57 of 63) of the patients with instable angina as leading diagnosis at discharge were correctly diagnosed on admission, but only 61.5 % (32 of 42) of the patients with infarction. (3) At discharge, 29.9 % (49 of 164) of the patients had a non-coronary leading diagnosis. Here, the most common were gastro-intestinal (55.1 %), costo-vertebral (18.4 %) and broncho-pulmonary (16.3 %).

Conclusions: (1) Troponin and myoglobin are helpful in patients without ST-segment elevation; yet, 4 h after admission, a safe exclusion of myocardial infarction is not possible. (2) The clinical diagnosis on admission is important. However, it corresponds with the leading diagnosis at discharge, based on coronary angiography, in only 50 to 75 %. Patients admitted with suspected ACS should be monitored for 24 h in the hospital (chest pain units or coronary care units). (3) Nearly one third of the patients initially admitted with suspected ACS show a non-coronary leading diagnosis, thus underlining the value of further investigations and of an interdisciplinary approach.