The diagnostic and prognostic value of cardiac Troponin T in bypass surgery

The purpose of this study was to verify the utility of serum Troponin T (TnT) in the diagnosis of myocardial damage after coronary surgery performed using different methods of myocardial protection. The prognostic value of TnT peak for a poor postoperative course was also investigated.

Forty-three patients were enrolled and randomised in 2 group: Group A (n. 22) receiving warm blood cardioplegia and Group B (n. 21) receiving cold blood cardioplegia. According to TnT peak levels 3 subgroups were identified: Subgroup 1 (TnT peak < than 1 ng/ml); Subgroup 2 (TnT peak between 1 and 3 ng/ml), Subgroup 3 (TnT peak >3 ng/ml). A comparison with the standard criteria for diagnosis of myocardial ischemia was performed for each subgroup of patients. A 12 months follow-up for the patients of subgroups 1 and 2 was also completed in order to evaluate the prognostic value of a higher TnT peak.

The overall patients subdivision in subgroup 1, 2 and 3 was 20 (46.5%), 14 (32.5%) and 9 (20.9%) respectively with no statistical difference for Group A or B. Only 7 of the patients of subgroup 3 (87%) matched the WHO diagnostic criteria for myocardial infarction. At the overall follow-up, 2 (14.28%) patients of subgroup 2, and 4 (20.0%) of subgroup 3, revealed a residual ischemia at the ECG-stress test even if none of these needed reoperation.

Our data confirmed the high sensitivity and specificity of TnT measurement in the diagnosis of myocardial infarction and minor myocardial damage. This study, however, failed to show any statistically significant difference of the TnT peak when using different strategies of myocardial protection. The late prognostic value of the TnT increase in the early post-operative course has to be confirmed from a further study.