Verdachtsdiagnose akutes Koronarsyndrom bei Patienten ohne ST-Hebung. Infarktausschluss, klinische Ersteinschaetzung und nicht-koronare Diagnosen

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

Risk stratification of chest pain patients by point-of-care cardiac troponin T and myoglobin measured in the emergency department

A prospective multicenter study including 1410 chest pain patients with suspected acute coronary syndromes was carried out to examine the predictive value of biological cardiac markers for adverse events measured by a point-of-care system. Admission cardiac troponin T (cTnT) and myoglobin were measured in parallel on a point-of-care system in the emergency department and -- together with CK-MB mass -- on lab analyzers. In a one-year follow-up, cardiac and non-cardiac death, acute myocardial infarction, unstable angina pectoris and need for revascularization were registered. Median time between onset of symptoms and admission was 285 min; 172 patients (12.2%) had no event during follow-up. If the cTnT, measured either by the point-of-care system or a conventional lab analyzer, was >0.05 microg/L, then the chance of a cardiac event during the follow-up period was doubled (18% vs. 9%). Serial cTnT measurement did not add any further value to the predictive power of the admission cTnT. Myoglobin and CK-MB mass identified increasing risk with increasing concentration quartiles; cardiac event rates were 2.8- to 4.4-fold higher between the quartiles with the lowest and those with the highest analyte concentration, respectively. There was no difference in non-cardiac death rates between any concentration quartiles. In conclusion, the prediction of clinical events by cardiac troponin T and myoglobin measured with a point-of-care analyzer in the emergency department was as good as that of the same cardiac markers and CK-MB mass measured on lab analyzers

Use of a quantitative point-of-care system greatly reduces the turnaround time of cardiac marker determination

The goal of this study was to examine whether point-of-care testing of cardiac markers in emergency departments or coronary care units generates a substantial reduction of the turnaround time compared with central laboratory testing. A total of 4609 samples from patients with suspected acute coronary syndromes attending each of 5 participating hospitals were used to measure cardiac troponin Ton a point-of-care system at the bedside, and 3447 of these samples were simultaneously sent to each hospital's central laboratory for an emergency determination of total CK. The time to central laboratory result varied broadly (from 52-147 minutes) from hospital to hospital. There was little difference between the hospitals in the time to result for the point-of-care system (range, 12-22 minutes). The overall gain in time from point-of-care testing compared with central laboratory measurements was 65 minutes (range, 34-135 minutes)

Diagnostic Efficiency of a Point-of-Care System for Quantitative Determination of Troponin T and Myoglobin in the Coronary Care Unit

This study was carried out to compare the time-dependent diagnostic sensitivity and specificity for acute myocardial infarction of 2 point-of-care tests for troponin T and myoglobin measured in routine use of coronary care units with those of the respective laboratory tests. A total of 794 consecutive patients with suspected acute coronary syndromes admitted to the coronary care units of 6 hospitals were enrolled in the study. Point-of-care tests and laboratory tests were measured in parallel from samples obtained serially on admission, and at 1, 2, 4, 6 to 8, 12, 24, and 48 hours from admission. The point-of-care tests achieved maximum sensitivities of 96% (troponin T) and 72% (myoglobin); and the maximum sensitivities of the laboratory tests were 96%, 81%, and 83% for troponin T, myoglobin, and CK-MB mass respectively. The specificities varied from 90 to 94% for point-of-care troponin T, 83 to 93% for point-of-care myoglobin, 97 to 99% for laboratory troponin T, 79 to 85% for laboratory myoglobin, and 95 to 100% for laboratory CK-MB mass. The following maximum areas under receiver-operator characteristics curves were obtained (at different times): point-of-care troponin T, 0.97; point-of-care myoglobin, 0.87; laboratory troponin T, 0.99; laboratory myoglobin, 0.89; and laboratory CK-MB mass, 0.96. In conclusion the point-of-care tests had a comparable clinical performance as established cardiac markers performed in the laboratory