Hs-cTnI less accurate at diagnosing MI in patients with prior CABG

High-sensitivity cardiac troponin I (hs-cTnI) loses diagnostic accuracy for myocardial infarction (MI) in patients who had undergone prior coronary artery bypass grafting (CABG), though it remains highly sensitive and specific, a new study has found.

Researchers conducted a secondary analysis of the APACE study, a large prospective multicentre study enrolling patients from 12 centres across five European countries. The present study included 5,200 patients, for whom the final diagnosis was centrally adjudicated by two independent cardiologists, using the third universal definition of MI.

Eight percent (n=392) of the patients had prior CABG and were significantly older than non-CABG counterparts. Of note, an adjudicated final diagnosis of MI occurred significantly more often for patients with vs without prior CABG (34 percent vs 16 percent; p<0.001). Levels of hs-cTnI at presentation were likewise significantly elevated in the CABG subgroup (median, 12.0 vs 4.0 ng/L; p<0.001).

The diagnostic accuracy of hs-cTnI for MI was significantly lower in patients with prior CABG, but nevertheless remained high (area under the curve, 0.91 vs 0.95; p=0.016).

When using the European Society of Cardiology 0/1h-hs-cTnI-algorithms, sensitivity and specificity for the diagnosis of MI remained high (100 percent and 93.5 percent, respectively) in patients with prior CABG, though the overall efficacy was lower than in the no-CABG subgroup (52 percent vs 74 percent; p<0.01).

“Although this secondary analysis is the largest diagnostic study ever performed in patients with prior CABG, it still may have been underpowered for some comparisons, especially regarding direct comparison of the various assays and long-term safety,” the researchers said.

“Given the relevant long-term mortality, optimal secondary preventive measures must be applied to all patients with prior CABG presenting with acute chest pain irrespective of acute triage decision,” they added.