Faculty Bibliography

BACKGROUND:Serum troponins are sensitive markers of myonecrosis and ischemia and are now widely used in clinical practice. Although percutaneous coronary intervention (PCI)-related creatine kinase-myocardial band isoenzyme (CK-MB) elevation has been associated with future cardiac events, the significance of troponin elevation in this setting is unknown. We sought to determine whether serum troponin I (Tn-I) elevation after PCI is associated with future cardiac events. Methods and Results Consecutive patients undergoing elective PCI underwent systematic postprocedure measurement of Tn-I and CK-MB levels. Serum levels were correlated with demographic, angiographic, and procedural characteristics and the development of major adverse cardiac events (MACE; defined as death, MI, or need for PCI or coronary bypass graft surgery) at 30 days, 6 months, and 1 year. In 286 consecutive procedures, postintervention myonecrosis-specific Tn-I was elevated in 13.6% of patients, and CK-MB was elevated in 12.9% of patients. Multivariable predictors of Tn-I elevation were procedural side branch occlusion and thrombus formation. Peak Tn-I and CK-MB values were well correlated (r = 0.81, P <.0001). Three-fold elevation of Tn-I after successful PCI was independently predictive of MACE (P =.01). CONCLUSIONS:Tn-I elevation after elective PCI is relatively common and is associated with procedural complications such as incidental side branch occlusion and thrombus formation. In addition, this study demonstrates that a 3-fold elevation of Tn-I after successful elective PCI is predictive of future cardiac events, especially the need for early repeat revascularization.

BACKGROUND:Previous animal studies have demonstrated that the transmural extent of acute myocardial infarction defined by contrast-enhanced MRI (ceMRI) relates to early restoration of flow and future improvements in contractile function. We tested the hypothesis that ceMRI would have similar predictive value in humans. METHODS AND RESULTS/RESULTS:Twenty-four patients who presented with their first myocardial infarction and were successfully revascularized underwent cine and ceMRI of their heart within 7 days (scan 1) of the peak MB band of creatine kinase. Cine MRI was repeated 8 to 12 weeks later (scan 2). The transmural extent of infarction on scan 1 and wall thickening on both scans were determined using a 72-segment model. A total of 524 of 1571 segments (33%) were dysfunctional on scan 1. Improvement in segmental contractile function on scan 2 was inversely related to the transmural extent of infarction on scan 1 (P=0.001). Improvement in global contractile function, as assessed by ejection fraction and mean wall thickening score, was not predicted by peak creatine kinase-MB (P=0.66) or by total infarct size, as defined by MRI (P=0.70). The best predictor of global improvement was the extent of dysfunctional myocardium that was not infarcted or had infarction comprising <25% of left ventricular wall thickness (P<0.005 for ejection fraction, P<0.001 for mean wall thickening score). CONCLUSION/CONCLUSIONS:In patients with acute myocardial infarction, the transmural extent of infarction defined by ceMRI predicts improvement in contractile function.