Postop stroke risk similar in single-center observation, but the issue remains controversial.

The partial clamping method for on-pump coronary artery bypass grafting (CABG) was not associated with higher risk of stroke as a complication in an observational study, but experts said the data don’t settle the issue.

The 30-day observed postoperative stroke rates came out a similar 1.5% with single aortic clamping and 1.4% with combined partial aortic clamping (17 of 1,107 patients versus 10 of 712 patients, P>0.99), as predicted from the nearly identical preoperative stroke prediction scores in the single center cohort.

Mortality rates at 30 days were likewise “equally low” (1.9% versus 1.8%, respectively,P>0.99), Danny Chu, MD, of the University of Pittsburgh, and colleagues reported online in JAMA Surgery.

“In patients with significantly compromised myocardial function who are undergoing complex cardiac operations, partial aortic clamping may provide a safe alternative,” the group concluded.

The issue has been controversial, they noted, because a small single-institutionrandomized trial showed better cerebral protection with single aortic clamping, whereas “several high-volume, high-performing cardiac surgery centers continued to perform on-pump CABG using the partial aortic clamping technique with relatively low stroke rates.”

The reason for conflicting studies is “not the aortic clamping; it is the patient,” each with her or his unique atherosclerotic burden in the ascending aorta and arch, Michael D. Crittenden, MD, of the VA Health Care System in St. Louis, Mo., argued in an accompanying editorial.

“Aortic manipulation is one of many risk factors for embolic stroke,” he wrote. “Clearly, patients undergoing anaortic surgery are not spared this complication. The study by Chu and colleagues highlights the fact that there are factors beyond aortic manipulation that we have yet to control.”

Timothy Gardner, MD, medical director of Christiana Care Health System’s Center for Heart & Vascular Health in Newark, Del., and a past president of the American Heart Association, wasn’t so equivocal.

From Chu’s findings, “it would be incorrect to assume that partial aortic clamping is safe for all patients,” he told MedPage Today.

“Experienced cardiac surgeons understand the importance of reducing aortic manipulation in a patients with atherosclerotic involvement of the ascending aorta,” he said. “As has been demonstrated in many reports, such patients are best managed with a single aortic clamping for both distal and proximal grafting.

“In the report by Chu et al, the single clamp patients were older and had increased risk factors for stroke compared to the partial clamp patient group. There likely was some selection bias in the surgeons’ decision to use the single clamp technique versus partial clamping.”

The retrospective cohort study included 1,819 patients receiving conventional on-pump, arrested-heart CABG for the first time as an isolated, non-emergent procedure at a single U.S. major academic medical center.

“To validate our findings, a prospective randomized trial designed to assess aortic clamping strategy for performing proximal coronary anastomosis as well as risk of postoperative stroke and distal embolic burden in CABG operations appears justified,” Chu’s group acknowledged.

“In the meantime, let’s hope that surgeons are not mislead by the authors’ unqualified conclusion statement that ‘no significant differences in post-op stroke were identified regardless of aortic clamping method used,'” Gardner cautioned