Prognostic significance of elevated creatine kinase MB after coronary bypass surgery and after an acute coronary syndrome: results from the GUARDIAN trial.
OBJECTIVE
To determine if the correlation between magnitude of creatine kinase-myocardial band release after coronary artery bypass surgery and 6-month mortality is comparable to that of patients admitted with an acute coronary syndrome.


METHODS
The GUARDIAN trial tested the efficacy of cariporide, an Na+/H+ exchange inhibitor, on reduction of myocardial ischemia or death in high-risk patients. We compared 6-month survival in a cohort of 2332 GUARDIAN patients scheduled for coronary artery bypass surgery at entry with 4233 acute coronary syndrome patients stratified by level of creatine kinase-myocardial band release. Cumulative 6-month survival by creatine kinase-myocardial band categories was performed using life table analysis, adjusting for variables known to impact prognosis using Cox regression.


RESULTS
The 6-month mortality rates for coronary artery bypass surgery patients with peak creatine kinase-myocardial band ratios of <1, > or =1 and <5, > or =5 and <10, and > or =10 upper limits of normal (ULN) were 5.8, 2.8, 5.9, and 12.0%, respectively (P <.0001). The 6-month mortality rates for acute coronary syndrome patients with peak creatine kinase-myocardial band ratios of <1, > or =1 and <5, > or =5 and <10, and > or =10 ULN were 6.3, 9.8, 10.0, and 12.3%, respectively (P <.0001). Patients with coronary artery bypass surgery or acute coronary syndrome had similar adjusted 6-month survival estimates at normal creatine kinase-myocardial band levels and when the creatine kinase-myocardial band level was > or =10 ULN. Patients with coronary artery bypass surgery had significantly better survival at intermediate enzyme levels (> or =1 and <10 ULN; P <.001).


CONCLUSIONS
Modest elevations of creatine kinase-myocardial band release (> or =1 and <10 ULN) after coronary artery bypass surgery are not associated with adverse 6-month survival, in contrast to that seen in acute coronary syndrome patients. Routine creatine kinase-myocardial band sampling should be considered in all higher-risk patients undergoing coronary artery bypass surgery procedures to identify the sizable cohort of patients with creatine kinase-myocardial band release > or =10 ULN; these patients may benefit from postoperative angiotensin-converting enzyme inhibitor and beta-blocker therapy. Newer cardioprotective agents that reduce the number of patients with marked creatine kinase-myocardial band release are currently being tested in large randomized controlled clinical trials.
D000208:Acute Disease; D000368:Aged; D001026:Coronary Artery Bypass; D003327:Coronary Disease / Q000097:blood* / Q000401:mortality / Q000601:surgery*; D003402:Creatine Kinase / Q000097:blood*; D052279:Creatine Kinase, MB Form; D005260:Female; D006146:Guanidines / Q000627:therapeutic use; D006801:Humans; D007527:Isoenzymes / Q000097:blood*; D008297:Male; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000188:drug therapy; D011184:Postoperative Period; D011379:Prognosis; D017923:Sodium-Hydrogen Exchangers / Q000037:antagonists & inhibitors; D013450:Sulfones / Q000627:therapeutic use; D015996:Survival Rate; D013577:Syndrome
D006146:Guanidines; D007527:Isoenzymes; D017923:Sodium-Hydrogen Exchangers; D013450:Sulfones; C093373:cariporide; D003402:Creatine Kinase; D052279:Creatine Kinase, MB Form