The utility of delta troponin in diagnosing significant coronary artery disease in patients with symptomatic atrial fibrillation.

BACKGROUND: Troponin I (cTnI) elevation is common in patients with atrial fibrillation (AF) but does not reliably indicate underlying coronary ischemia. We investigated whether dynamic changes in cTnI value (delta troponin) are useful in revealing significant coronary artery disease (sCAD) in patients presenting with symptomatic AF. METHODS: We conducted a retrospective case-control study analyzing serial cTnI values in 231 patients presenting with symptomatic AF who had an objective assessment for underlying CAD within 6 months of the index admission. Diagnostic performance of an elevated cTnI (>0.04 μg/L) only, and elevated cTnI coupled with Youden Index derived cutoffs for absolute and relative changes in troponin, for distinguishing patients with sCAD, was evaluated. RESULTS: A total of 107 patients had an elevated cTnI on serial measurements. In this group, the area under the receiver operating characteristic curve was 0.69 [95% confidence interval (CI), 0.56-0.81] for relative delta troponin and 0.71 (95% CI, 0.59-0.83) for absolute delta troponin. The optimal diagnostic cutoff for relative delta troponin was > -0.42, and > -0.055 μg/L for absolute delta troponin. The specificity of elevated troponin to diagnose sCAD increased from 56 to 77% when relative delta troponin was added, and to 88% with absolute delta troponin. Although the sensitivity of cTnI elevation (57.1%) decreased to 50% for relative and 35.7% for absolute delta troponin, the negative predictive values were high and similar at 86%. CONCLUSION: When added to the troponin peak, delta troponin is a promising test for the diagnosis of significant coronary artery disease in patients presenting with symptomatic AF with elevated cTnI. This result requires prospective validation in a larger cohort of patients.