Department of Cardiology, Athens Euroclinic, 9 Athanasiadou Str, 115 21 Athens, Greece
* Tel.: +30-210-641-6600; fax: +30-210-681-9779
E-mail address: dkatrits{at}otenet.gr
We read with great interest the meta-analysis by Roe and colleagues1 on the prognostic significance of creatinine kinase MB isoenzyme (CK-MB) elevations following percutaneous coronary interventions (PCI) in patients with acute coronary syndromes. We do concur with the conclusions of this study regarding the prognostic significance of even minor degrees of iatrogenic necrosis. However, this observation is not relevant only to this particular clinical setting. Although not referenced by Roe et al.,2 we have previously shown that any increase in CK-MB following PCI, in general, is associated with a statistically and clinically significant increase in the subsequent risk of death, regardless of the presence of an acute coronary syndrome. Our meta-analysis included seven studies with CK-MB measurements and survival outcomes on 23,230 subjects who underwent PCI (mean follow-up, 634 months per study). By random effects, 19% of the subjects had 15-fold CK-MB elevations, while only 6% had 5-fold elevations. The mortality relative risk increased 1.5-fold with 13-fold CK-MB elevations, 1.8-fold with 35-fold elevations and 3.1-fold with over 5-fold elevations. Thus, approximately 1 in 5 subjects undergoing PCI will have an elevation of CK-MB of 15-fold, and 1 in 15 subjects will have an even larger increase. Any CK-MB increase is associated with a potential increase in the subsequent risk of death during follow-up. One to 3-fold CK-MB elevations increase the risk of death by approximately 50%. In a step-wise fashion the risk is increased by 80% with 35-fold CK-MB elevations and is tripled with over 5-fold CK-MB elevations. This is of clinical importance as post-PCI, the CK-MB isoenzyme increases of up to five times the upper limit of normal have typically not been found to be statistically significant predictors of survival and their clinical meaning has been questioned.3 Nevertheless, the majority of post-PCI CK-MB elevations are in this range, with the majority in the range of 1 to three times the upper limit of normal.4
Therefore, there is now evidence that risk stratification should include routine surveillance of cardiac enzyme levels post- procedure. This should be completed, not only for ACS patients as suggested by the aforementioned articles, but also for any patient subjected to PCI.
References