Circulating Cardiac Troponin I in Severe Congestive Heart Failure

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Abstract
Background Spontaneous progression of severe congestive heart failure is structurally characterized by cellular degeneration and multiple foci of myocardial cell death. The cardiac muscle isoform of troponin I is uniquely expressed in the adult human myocardium, and an increase in its circulating levels is highly indicative of myocardial injury. Accordingly, we addressed the usefulness of cardiac troponin I as a sensitive and specific molecular marker of congestive heart failure in patients with severely reduced left ventricular performance. Methods and Results A new generation single-step immunoenzymoluminometric assay with high analytical sensitivity was used to assess cardiac troponin I in patients with severe congestive heart failure, healthy blood donors, and hospitalized control subjects without known cardiac disease. The cardiac troponin I concentration (mean±SEM) was 72.1±15.8 pg/mL in heart failure patients and 20.4±3.2 and 36.5±5.5 pg/mL in healthy and hospitalized control subjects, respectively ( P <.01 versus heart failure patients). When both control groups were considered, the mean cardiac troponin I level was 25.4±2.9 pg/mL ( P <.01 versus heart failure patients). Creatine kinase MB mass and myoglobin concentrations remained within the normal range in all groups. Conclusions These data (1) provide the first evidence for ongoing myofibrillar degradation and increased cardiac troponin I levels in patients with advanced heart failure and (2) show potential usefulness of cardiac troponin I as a specific and sensitive new serum marker molecule in severe congestive heart failure.