High background levels compromise the use of cardiac troponin I RNA detection in peripheral blood as a diagnostic tool in cardiology

The detection of cardiac troponins in peripheral blood as protein markers o f myocardial infarction is a new diagnostic tool in the diagnosis of cardia c disease. In order to increase the sensitivity and specificity of this dia gnostic approach, a reverse transcription polymerase chain reaction assay h as been developed to detect the mRNA encoding cardiac troponin I from myoca rdial cells hypothetically released from damaged cardiac tissue. The detect ion is specific for cardiac troponin I mRNA, with no amplification of homol ogous sequences of other troponin I isoforms, i.e., troponin I from skeleta l muscle cells, However, a strong amplification signal for cardiac troponin I mRNA was detected in samples of peripheral blood from healthy human volu nteers. In patients with acute myocardial infarction or angina pectoris, th e cardiac troponin I mRNA levels were not increased over background levels. In conclusion, a reverse transcription polymerase chain reaction approach based on the amplification of cardiac troponin I mRNA is not feasible in th e diagnosis of cardiac diseases.