What is the optimal myocardial preservation strategy at re-operation for aortic valve replacement in the presence of a patent internal thoracic artery?

Objective: The optimal myocardial preservation strategy at re-operation for aortic valve replacement (AVR) after prior coronary artery bypass grafting (CABG) in the presence of a patent internal thoracic artery (ITA) remains undefined. Methods: Patients undergoing AVR after prior CABG at our institution between 1 January 1996 and 31 December 2007 were identified; operative notes and outcomes were reviewed. Results: Of 628 patients with prior CABG undergoing AVR with or without concomitant procedures, 427 patients had a patent ITA. In 390, management of the ITA was detailed in the operative note, including 251 in whom it was clamped and 139 in whom it was left uncontrolled. Groups were demographically similar, although re-operative CABG was more frequent in the clamped group (42% vs 23%, p< 0.001). The operative mortality rate among those undergoing only AVR ± CABG was 7.7% (19/246), while that for all cases was 10.8% (42/390), and was lower when the ITA was left uncontrolled both for AVR ± CABG (4.1% vs 10.1%, p= 0.08) and overall (7.2% vs 12.7%, p= 0.09). By multivariate analysis, leaving the ITA uncontrolled appeared protective (odds ratio (OR) 0.46, p= 0.08). There was no clear trend supporting an optimal perfusion temperature when the ITA was left uncontrolled. Conclusions: Efforts to control the patent ITA at re-operation for AVR after prior CABG increase risk of injury and may actually increase operative mortality rate compared with leaving this critical graft open and perfusing the heart.