Strategies for the early diagnosis of acute myocardial infarction using biochemical markers

We evaluated different diagnostic strategies for the early diagnosis of acu te myocardial infarction, combining sensitivity and specificity of differen t markers evaluated singly and using combination testing in parallel and se rial modes. Myoglobin, cardiac troponin I (TnI), creatine kinase (CK), and CK-MB mass were tested in blood samples from 26 patients with acute myocard ial infarction collected at admission (T-0; mean = 3.3 hours from the onset of chest pain) and 3 and 6 hours later The comparison group was made up of 70 patients with renal failure, skeletal muscle diseases, stable angina un stable angina, and chest pain of nonischemic origin. Single rests showed di fferent sensitivities in relation to the different release kinetics; myoglo bin was the most sensitive (69% at T-0) although less specific (46%), and T nI showed the highest specificity (90%) and a sensitivity of 54%. Combinati on testing in a parallel mode using myoglobin and TnI or CK-MB had the same sensitivity and specificity as myoglobin tested singly. The best combinati on in a serial mode is myoglobin and TnI (at T-0 sensitivity 54%; specifici ty 98%), as confirmed by the analysis of the positive predictive value, the negative predictive value, and the accuracy evaluated as a function of dif ferent disease prevalences.