Will the left circumflex artery be affected if atrioventricular groove disruption occurs during mitral valve replacement?

Yes, the left circumflex artery (LCX) is at significant risk during atrioventricular groove disruption in mitral valve replacement.

The LCX runs in close anatomical proximity to the posterior mitral annulus within the AV groove, making it highly vulnerable to injury during mitral valve surgery, particularly when AV groove disruption occurs. 1

Mechanism of Injury

The circumflex artery can be injured through two primary mechanisms during mitral valve replacement:

• Direct injury: From sutures that encircle or transfix the vessel 2
• Indirect injury: From tissue distortion, compression, or kinking of the vessel due to AV groove disruption or annular manipulation 1, 3

When AV groove disruption occurs—whether from aggressive decalcification in mitral annular calcification (MAC) cases or from annular separation—the anatomical relationships are distorted, placing the LCX at even greater risk of compression or occlusion 1, 4.

Clinical Presentation

The clinical presentation of LCX injury is highly variable and unpredictable 1:

• Intraoperative findings: Wall motion abnormalities, ECG changes, malignant arrhythmias, inability to wean from cardiopulmonary bypass, cardiogenic shock
• Delayed presentation: Some patients may be initially asymptomatic intraoperatively but develop findings postoperatively 1, 3
• Late complications: Chronic heart failure with reduced ejection fraction, persistent ischemia 3, 5

Management Algorithm

When circumflex injury is diagnosed intraoperatively, immediate revascularization is mandated in hemodynamically unstable patients despite optimal inotropic or intra-aortic balloon pump support 1:

For Hemodynamically Unstable Patients:

1. Coronary artery bypass grafting to the lateral wall is preferred 1

   • Use apical suction devices to facilitate safe exposure
   • Avoid excessive cardiac lifting to minimize further annular injury

2. Alternative: Revision of valve sutures/prosthesis if technically feasible 1

   • Consider based on: MVR complexity, MAC distribution, presence of annular patch, coronary anatomy, conduit availability

For Hemodynamically Stable Patients:

Percutaneous coronary intervention is an effective and safe solution, especially for circumflex kinking 1

• Transfer to catheterization laboratory (or utilize hybrid operating room if available)
• Prompt diagnostic angiogram should always be considered in borderline situations to avoid serious risks of undiagnosed perioperative ischemia 1

Medical Management:

In select cases where surgical/percutaneous intervention carries prohibitive risk, medical management of ischemia may be considered 1

Critical Pitfalls to Avoid

• Failure to recognize delayed presentation: Not all LCX injuries manifest immediately; maintain high index of suspicion postoperatively 1, 3
• Underestimating the risk in MAC cases: Heavy calcification increases both the risk of AV groove disruption and subsequent LCX injury 1
• Delaying diagnostic angiography: In borderline cases, prompt angiography prevents catastrophic undiagnosed ischemia 1
• Excessive cardiac manipulation during CABG: When grafting is required, minimize heart lifting to avoid further annular injury 1

Prevention Strategies

The 2025 AATS guidelines emphasize that the extent of decalcification should be tailored to patient risk profile and surgical expertise 1. In high-risk patients with extensive MAC, consider:

• Hybrid transcatheter approaches that avoid extensive annular manipulation 1
• Respect strategies (working around calcium) rather than aggressive Resect strategies 1
• Preoperative CT imaging to map LCX course relative to the mitral annulus

The surgeon must balance the competing risks of inadequate valve implantation versus the potentially life-threatening complication of LCX injury when AV groove integrity is compromised 1.