Several studies have reported that elevation of cardiac creatine kinase (CK) enzymes after percutaneous coronary intervention (PCI) is associated with an increase in cardiac morbidity and mortality during follow-up. However, it remains unclear if enzyme elevation contributes to the adverse outcomes or is simply a marker for adverse events. We conducted a case- control study to determine if angiographically determined atherosclerotic plaque burden correlated with CK elevation. Patients (cases, n = 23) with CK elevation after PCI were identified along with 46 age- and gender-matched controls without CK elevation. Detailed angiographic analysis quantified the percentage of coronary artery length with any luminal irregularity, a surrogate for plaque burden. The CK elevation group was characterized by a greater number of smokers (65% vs 33%, p = 0.02), more thrombus-containing lesions (22% vs 2.2%, p = 0.014), and more frequent abrupt closure (13% vs 0%, p = 0.03). In addition, the case group had a 50% increase in atherosclerotic plaque burden compared with controls (30 ± 14% vs 20 ± 14%, p = 0.006). These data suggest that CK elevation after PCI is a marker for more extensive atherosclerosis, which may explain the worse prognosis of these patients. (C) 2000 by Excerpta Medica, Inc.