A patient with coronary artery disease may experience myocardial infarction in the perioperative period for a coronary artery bypass graft (CABG) procedure.
Criteria for a CABG-related myocardial infarction - both of the following:
(1) elevation of the serum cardiac biomarker value (typically troponin) with a normal baseline value
(2) one or more of the following:
(2a) new pathological Q waves or new left branch block (LBBB)
(2b) angiographic documented new graft or native coronary artery occlusion
(2c) imaging evidence of new loss of viable myocardium
(2d) imaging evidence of new regional wall motion abnormality
where:
• An elevated serum troponin is defined as greater than 10 times the 99th percentile for the reference range. This takes into account minor increases associated with surgery.
• The release of cardiac biomarker is increased if the procedure includes valve replacement or if the patient is on-pump.
Differential diagnosis of the myocardial infarction includes:
(1) trauma from suture placement or manipulation of the heart
(2) coronary artery dissection
(3) global or regional ischemia related to inadequate intra-operative cardiac protection
(4) microvascular event related to reperfusion
(5) myocardial injury induced by oxygen free radical generation
(6) failure to re-perfuse areas of the myocardium not supplied by the graftable vessels
