Patients with extensive and diffuse coronary artery disease constitute a high-risk population for surgical coronary revascularisation. Previous studies showed a direct correlation between smaller coronary artery diameters and long-term adverse post-coronary artery bypass surgery (CABG) outcomes.^1,2 Whether grafting smaller calibre coronary vessels has a direct relationship with surgery-related myocardial infarction, however, is unclear and, if so, whether the location of the perioperative infarction differs according to CABG technique (on-pump or off-pump CABG).

Delayed-enhancement magnetic resonance imaging (MRI) can quantify irreversible myocardial injury (seen as hyperenhancement) and is superior to single-photon emission computed tomography imaging for the identification of subendocardial myocardial infarction.³ We have recently reported that in patients randomly assigned to either on-pump or off-pump CABG techniques, the groups did not differ significantly in the extent of surgery-related irreversible myocardial injury when assessed by delayed-enhancement MRI.⁴ Taking advantage of the existence of this group of patients undergoing CABG, we now set out to determine whether angiographic grading of target vessel diameter predicts the occurrence of irreversible myocardial injury after grafting. A secondary goal was to see whether patients with new surgery-related hyperenhancement would have focal injury in the territory (downstream) of the grafted artery or diffusely in the subendocardium, unrelated to the location of the grafted vessel.

METHODS

The study was approved by our institutional ethics committee. Both the patient population characteristics and cardiovascular MRI protocol …