Use of cTnI/cTnT ratio improves AMI, myocardial injury discrimination

The ratio of cardiac troponin (cTn) I and T helps differentiate acute necrotic from chronic/non-necrotic myocardial injury in clinical and experimental studies.

Moreover, the cTnI/cTnT ratio “improves type 1 vs type 2 acute myocardial infarction (AMI) discrimination, offering potential diagnostic value and challenging the interchangeability of cTnI and cTnT,” the researchers said.

In this study, researchers classified participants from three prospective clinical studies with centrally adjudicated diagnoses as having no known, chronic, or acute cardiac disease. They measured circulating concentrations of high-sensitivity (hs)-cTnI and hs-cTnT and used regression models to explore how the cTnI/cTnT ratio was associated with these diagnostic categories.

The research team validated the findings internally and externally. They also examined the cTnI/cTnT ratio in four experimental cardiomyocyte models simulating mild non-lethal and lethal injury.

A total of 9,704 individuals were analysed. The highest cTnI/cTnT ratio was observed in participants with acute cardiac disease (2.06, 95 percent confidence interval [CI], 1.89‒2.26), nearly four times higher than in those with chronic (0.66, 95 percent CI, 0.60‒0.72) and no known cardiac disease (0.50, 95 percent CI, 0.43‒0.59). These findings persisted across alternative hs-cTnI assays and external validation cohorts.

In experimental models, mild non-lethal injury produced cTnT-dominant release (cTnI/cTnT ratio ∼0.5), while lethal injury generated cTnI-dominant release (cTnI/cTnT ratio >1).

“Incorporating the cTnI/cTnT ratio as a predictor in a statistical model alongside cTnI and cTnT improved discrimination between type 1 and 2 AMI (AUC, 0.73, 95 percent CI, 0.70‒0.76 vs 0.70, 95 percent CI, 0.67‒0.73; p< 0.01),” the researchers said.