Biochemical markers of cardiac damage: from efficiency to effectiveness

Testing for the diagnosis of acute myocardial infarction and other diseases included in the spectrum of the so-called "acute coronary syndrome" is rapidly changing from the traditional enzymatic assays to mass measurement of more specific and sensitive markers (cardiac troponins, CK-MB and myoglobin). Several questions have arisen since the introduction of these new markers into the clinical setting: the choice of strategies for optimizing the utilization of biochemical assays combining different (early and specific) markers, the rationale for sampling specimens and the identification of clinically useful turnaround times. The impressive clinical specificity and sensitivity assured by the measurement of cardiac troponins should be used for improving the effectiveness of patients' diagnosis and treatment. Troponins could be the paradigm of how a new diagnostic test and a therapeutic advance can be combined to the benefit of patients with acute coronary syndromes. In fact, in acute myocardial infarction (AMI) patients as well as in patients suffering from stable and unstable angina, the measurement of troponins alone, or combined to that of other biochemical markers, should be of practical value for the diagnosis, for the prognosis and for selecting the most effective therapeutic treatment. Limitations in cardiac markers should be classified into two groups: temporary and intrinsic limitations. Temporary limitations are: (a) current assays are not specific as to the analyte, (b) the limited standardization precludes a comparison between results obtained with different techniques. Intrinsic limitations are the elevation of troponins in the so-called "minor myocardial damage", which often cannot be confirmed by other techniques, the evidence that other heart diseases, such as congestive heart failure and myocarditis, can lead to an increase in troponin concentrations, and finally that troponin is not an early marker. A sound cooperation between cardiologists, physicians and laboratory specialists in explaining and understanding the advantages and limitations of current biochemical markers should allow us to move from efficiency to clinical effectiveness.