Prognostic value of isolated troponin I elevation after percutaneous coronary intervention

Mild elevations of cardiac troponin are frequent after percutaneous coronary intervention (PCI). Their prognostic value is uncertain in the absence of changes in creatine kinase-MB (CK-MB).

We evaluated the relation between isolated elevations of cardiac troponin I (cTnI) and all-cause mortality. We studied 3494 consecutive patients who underwent PCI in 16 Italian tertiary cardiology centers. CK-MB and cTnI were analyzed in a central laboratory. Duration of follow-up was 2 years. The present analysis was restricted to 2362 patients with normal CK-MB and cTnI values at baseline and no CK-MB elevation after PCI. A rise in cTnI after PCI >0.15 ng/mL, the upper reference limit, was found in 932 patients (39.4%). A rise >0.45 ng/mL (>3×upper reference limit) was found in 467 patients (19.7%). Compared with patients with normal cTnI, those with cTnI elevation >0.15 ng/mL showed a slightly increased mortality (3.8% versus 2.6%; hazard ratio, 1.53; 95% confidence interval, 0.97 to 2.42; P=0.069). A cTnI elevation >0.45 ng/mL was associated with a higher risk of mortality (4.5% versus 2.7%; hazard ratio, 1.68; 95% confidence interval, 1.01 to 2.80; P=0.044), which, however, did not remain significant after adjustment for concomitant risk factors (hazard ratio, 1.45; 95% confidence interval, 0.86 to 2.46; P=0.162). Postprocedural cTnI elevation was associated with coronary and clinical features consistent with a worse risk profile.

In the absence of a rise in CK-MB, elevated cTnI levels after PCI are associated with a modest increased risk of death. However, this is not independent of the concomitant adverse baseline clinical characteristics of these patients.