Cardiac troponin I is degraded and released faster from necrotic tissue than troponin T, returning to baseline concentrations at 54 hours compared with 168 hours in a rat model.
What is the mechanism behind the faster clearance and higher peak concentrations of cTnI compared to cTnT in acute myocardial infarction?
Faster degradation and release from necrotic tissue, rather than differences in circulation clearance, explain why cTnI reaches higher peak concentrations and normalizes faster than cTnT in acute myocardial infarction.
Absolute Event Rate: 54% vs 168%
BACKGROUND: Although cardiac troponin I (cTnI) and troponin T (cTnT) form a complex in the human myocardium and bind to thin filaments in the sarcomere, cTnI often reaches higher concentrations and returns to normal concentrations faster than cTnT in patients with acute myocardial infarction (MI). METHODS: We compared the overall clearance of cTnT and cTnI in rats and in patients with heart failure and examined the release of cTnT and cTnI from damaged human cardiac tissue in vitro. RESULTS: Ground rat heart tissue was injected into the quadriceps muscle in rats to simulate myocardial damage with a defined onset. cTnT and cTnI peaked at the same time after injection. cTnI returned to baseline concentrations after 54 h, compared with 168 h for cTnT. There was no difference in the rate of clearance of solubilized cTnT or cTnI after intravenous or intramuscular injection. Renal clearance of cTnT and cTnI was similar in 7 heart failure patients. cTnI was degraded and released faster and reached higher concentrations than cTnT when human cardiac tissue was incubated in 37°C plasma. CONCLUSION: Once cTnI and cTnT are released to the circulation, there seems to be no difference in clearance. However, cTnI is degraded and released faster than cTnT from necrotic cardiac tissue. Faster degradation and release may be the main reason why cTnI reaches higher peak concentrations and returns to normal concentrations faster in patients with MI.
Starnberg et al. (Thu,) conducted a other in Acute Myocardial Infarction and Heart Failure (n=7). Cardiac troponin I (cTnI) vs. Cardiac troponin T (cTnT) was evaluated on Time to return to baseline concentrations after simulated myocardial damage in rats. Cardiac troponin I is degraded and released faster from necrotic tissue than troponin T, returning to baseline concentrations at 54 hours compared with 168 hours in a rat model.