Risk of retinal microembolism after off-pump and on-pump coronary artery bypass surgery

In order to investigate the neuroprotective efficacy of off-pump coronary artery bypass surgery (OPCAB) over conventional on-pump coronary artery bypass surgery (CCAB), we have performed a prospective randomized study evaluating retinal circulation changes after OPCAB and CCAB.

Twenty patients were randomized to OPCAB or CCAB. Retinal fluorescein angiography and 60 degrees black-and-white as well as color fundus photographs of both eyes of each patient were taken 1 to 24 h before and 5 to 6 days after the operation.

Patients undergoing OPCAB had more severely stenosed carotid arteries (P=0.075), higher incidence of slightly diseased ascending aorta (P=0.087) and higher Northern New England Cardiovascular Study Group stroke risk score (P=0.075). Neither stroke nor transient ischemic attack occurred postoperatively in these patients. Inferotemporal retinal arterial embolization and microinfarction was detected in one patient after CCAB, but in none of the OPCAB group.

The risk of retinal embolism can be minimized by the use of OPCAB and, most likely, by adequate epiaortic ultrasound scanning of the ascending aorta and avoiding clamping in case of severely diseased aorta.