A new study investigating the diagnostic value of cardiac troponins in reversible myocardial ischemia reveals that while cardiac troponins are not always elevated, they can complement regadenoson single-photon emission computed tomography myocardial perfusion imaging (SPECT MPI), commonly known as Lexiscan, in evaluating patients with anginal symptoms. The results were published in Annals of Clinical Cardiology.

The study assessed 96 patients who presented with anginal chest pain or angina equivalents and had objective evidence of reversible myocardial ischemia on stress Lexiscan imaging. Investigators analyzed their cardiac troponin I (cTnI) and troponin T (cTnT) levels to evaluate the correlation with ischemia severity and other clinical variables.

Elevated cTnI levels (≥0.02 ng/mL) were found in 60.3% of the 63 tested patients, while elevated cTnT levels (≥0.010 ng/mL) were found in 60.6% of the 33 tested patients. Median cTnI was 0.10 ng/mL and median cTnT was 0.051 ng/mL. Interestingly, the majority of patients (63.5%) showed no ischemic changes on EKG, despite having perfusion defects on imaging.

The study found that cTnI tended to be elevated even in cases of mild ischemia, although the difference was not statistically significant. On the other hand, cTnT showed a statistically significant increase in patients with both ischemic EKG changes and severe ischemia on imaging.

Researchers concluded that Lexiscan imaging remains highly sensitive for detecting myocardial ischemia, even when EKG and troponin results are inconclusive. Moreover, there was a potential complementary role of cTnI and cTnT, with cTnI being more sensitive to mild ischemia and cTnT indicating more severe myocardial injury.