Research article

Intermediate and high peri-operative cardiac enzyme release following isolated coronary artery bypass surgery are independently associated with higher one-year mortality

N Newall¹ , AY Oo² , ND Palmer³ , AD Grayson⁴ , TJ Hine⁵ , RH Stables³ , BM Fabri² and DR Ramsdale³

¹  Department of Cardiology, Arrowe Park Hospital, Wirral, UK

²  Department of Cardiothoracic Surgery, The Cardiothoracic Centre, Liverpool, UK

³  Department of Cardiology, The Cardiothoracic Centre, Liverpool, UK

⁴  Department of Clinical Governance, The Cardiothoracic Centre, Liverpool, UK

⁵  Department of Clinical Biochemistry, The Royal Liverpool and Broad Green University Hospital, UK

author email corresponding author email

Journal of Cardiothoracic Surgery 2006, 1:20doi:10.1186/1749-8090-1-20

Published:	15 August 2006

Abstract

Background

The relationship between cardiac enzyme (CE) release following coronary artery bypass surgery (CABG) and medium term outcome is unclear. We sought to determine the relationship between post-operative CE release and one-year survival following isolated CABG.

Methods

Over three years 3,024 consecutive patients underwent isolated CABG. Patient characteristics were prospectively recorded in a cardiac surgical database. CE release, taken as the highest single measurement recorded in the first 24 hours post-op, was abstracted from an electronic archive. All cause mortality was taken from a national registry of deaths.

Results

Data were complete for 2,860 (94.6%) patients. CK-MB isoenzyme (reference range 5–24 U/l) was recorded in 2,568 (89.8%), total CK in 292 (10.2%).

CE release three or more times the upper limit of the reference range (ULR) were recorded in 498 (17.4%) patients, 163 (5.7%) patients had CE more than six times ULR. There were 122 deaths (4.3%). Cox proportional hazards analysis showed that CE release 3–6 times ULR (adjusted HR 2.1 [95% CI: 1.6 to 2.6], p = 0.002) and CE release six or more times the ULR (adjusted HR 5.0 [95% CI: 4.5 to 5.4], p < 0.001) were independently associated with increased one-year mortality.

Conclusion

Cardiac enzyme release following CABG is associated with increased one-year all-cause mortality. The definition of peri-operative myocardial infarction following CABG should include elevation of CK-MB three or more times the upper limit of normal.