When performing a Coronary Artery Bypass Graft (CABG) and Mitral Valve Replacement (MVR) together, which procedure does the operating surgeon typically perform first and why?

From the Guidelines

In combined coronary artery bypass grafting (CABG) and mitral valve replacement (MVR) surgery, surgeons typically perform the CABG first, followed by the MVR. This sequence is preferred because completing the coronary revascularization first ensures adequate myocardial perfusion before the heart is subjected to the additional stress of valve surgery, as supported by the 2021 ACC/AHA guideline for the management of patients with valvular heart disease 1. By establishing improved blood flow to the heart muscle early in the procedure, the surgeon reduces the risk of ischemic complications during the more complex valve replacement phase. Additionally, performing CABG first allows the surgeon to work in a relatively dry field before opening the heart chambers for the valve procedure, which helps maintain optimal visualization. The technical aspects also favor this sequence, as completing the distal anastomoses of the bypass grafts is easier before the heart is manipulated for valve replacement. Some key points to consider in this approach include:

• The presence of uncorrected CAD has been shown to negatively impact both perioperative and late outcomes of surgery for VHD, making concomitant CABG a favored approach 1.
• Combined CABG and valve surgery reduces the rate of perioperative myocardial infarction, and incomplete revascularization is associated with greater post-operative LV systolic dysfunction and a reduced survival rate after surgery as compared with patients who receive complete revascularization 1.
• The use of the left internal thoracic artery for bypass of stenoses of the left anterior descending coronary artery is reasonable, as noted in the 2008 focused update incorporated into the ACC/AHA 2006 guidelines for the management of patients with valvular heart disease 1. However, in specific situations where the mitral valve pathology is severe and causing significant hemodynamic compromise, the surgeon might prioritize the valve replacement, as the ultimate decision depends on the patient's specific cardiac anatomy, the severity of each condition, and the surgeon's assessment of which pathology poses the more immediate threat to cardiac function. The 2014 AHA/ACC guideline for the management of patients with valvular heart disease also supports the combination of CABG and AVR, stating that it reduces the rates of perioperative MI, perioperative mortality, late mortality, and morbidity when compared with patients not undergoing simultaneous CABG 1. Overall, the most recent and highest quality evidence supports performing CABG first in combined CABG and MVR surgery, as it ensures adequate myocardial perfusion and reduces the risk of ischemic complications.

From the Research

Surgical Approach for CABG and MVR

When a patient is posted for coronary artery bypass grafting (CABG) and mitral valve replacement (MVR) together, the operating surgeon typically performs the CABG first. This approach is based on several studies that have investigated the outcomes of combined CABG and MVR procedures.

Rationale for CABG First

• The study by 2 found that patients with moderate to severe or severe mitral regurgitation (MR) benefited from concomitant MVR and CABG, with improved postoperative echocardiography showing an improvement of mitral regurgitation in 95% of CABG+MVR patients.
• The study by 3 demonstrated that CABG+MVR can be performed safely in patients with moderate-to-severe ischemic mitral regurgitation, with lower rates of postoperative low cardiac output and atrial fibrillation compared to CABG only.
• However, the study by 4 found that MVR+CABG patients had higher mortality and composite morbidity compared to MVR patients, highlighting the importance of careful patient selection and risk assessment.

Considerations for MVR First

• The study by 5 compared mitral valve repair and replacement with concomitant CABG, finding no significant difference in in-hospital mortality between the two groups, but higher incidence of low cardiac output syndrome and longer in-hospital stay in the MVR+CABG group.
• The meta-analysis by 6 found that long-term survival was higher in the CABG only group, with no significant improvement in long-term survival rates of patients treated with both CABG and MVR.

Key Factors Influencing Surgical Approach

• Patient selection and risk assessment are crucial in determining the optimal surgical approach.
• The severity of mitral regurgitation and the presence of other comorbidities, such as renal insufficiency and older age, can influence the decision to perform CABG first or MVR first.
• The surgical team's experience and expertise in performing combined CABG and MVR procedures also play a significant role in determining the optimal approach.