["Studies on the glycoprotein IIb-IIIa receptor blocker abciximab in patients undergoing percutaneous coronary intervention consistently show a reduction in procedure-related myocardial infarction. Some such infarcts are characterized by elevated creatine kinase or creatine kinase-MB, without apparent clinical symptoms. The clinical relevance of such 'creatine kinase leaks' has been questioned. Therefore we investigated the relationship between post-procedural creatine kinase-MB elevation and outcome at the 6 month follow-up.", 'Creatine kinase-MB, or total creatine kinase values were analysed in 5025 out of 6156 patients enrolled in the CAPTURE, EPIC and EPILOG studies. A consistent gradual increase in 6 month mortality was observed as creatine kinase-MB or creatine kinase levels increased: 1.1%, 2.1%, 1.8%, 3. 6% and 6.7% for creatine-MB or creatine ratios (relative to upper limit of normal) <1, 1-3, 3-5, 5-10 and >/=10, respectively. Also the incidence of death or (recurrent) myocardial infarction was related to creatine kinase-MB or creatine kinase ratios. Subsequent revascularization was not related to periprocedural myocardial infarction. By multivariable analysis, correcting for clinical and angiographic characteristics, mortality at 6 months was related to the enzyme (creatine kinase, creatine kinase-MB) ratio, a history of heart failure and age. The combined end-point of death and myocardial infarction was also related to these factors, as well as to a history of bypass surgery and unstable angina.'] Is minimal myocardial damage during coronary intervention associated with impaired outcome?