Background: Early prediction of infarct size and of the subsequent development of congestive heart failure (CHF) and pulmonary hypertension (PH) would be useful in therapeutic trials using the rat myocardial infarction (MI) model.
Methods: A total of 194 rats were subjected to MI or sham surgery, and plasma cardiac troponin T (cTnT) was measured 24 h after surgery in rats. Echocardiography was performed after 2 and 5 weeks. Hemodynamic and morphometric parameters were evaluated 5 weeks after MI.
Results: cTnT had strong positive correlations with left ventricular (LV) wall motion abnormalities at 2 and 5 weeks (R=.85 and .89; P<.0001), and with histological infarct size (R=.87, P<.0001). cTnT ≥5.1 μg/l predicted LV wall motion abnormalities ≥ 30% with a sensitivity of 90.9% and specificity of 84.0%. Rats with cTnT≥5.1 μg/l developed PH [right ventricular (RV) systolic pressure 37 ± 3 vs. 23 ± 0.6 mmHg], RV hypertrophy (RV/LV+septum weight 42 ± 4% vs. 24 ± 0.5%), and lung structural remodeling (all P<.01).
Conclusion: Early single cTnT measurement correlates with infarct size in rats, and a cutoff value of 5.1 μg/l provides good sensitivity and specificity to predict CHF with secondary PH. cTnT could be used for treatment allocations in therapeutic trials of secondary pulmonary hypertension using this model.
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