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CABG: A continuing evolution

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ABSTRACT

Use of coronary artery bypass grafting (CABG) has had a resurgence, as clinical trial data emerged showing that it remains the standard of care for patients with complex lesions. Debate exists regarding various factors, including endoscopic vs open vein-graft harvesting, single vs bilateral mammary artery grafts, radial artery vs saphenous vein grafts, right internal mammary artery vs radial artery grafts, and on-pump vs off-pump surgery. More recent developments include minimally invasive approaches, robotics, and hybrid revascularization, which are changing the risk-benefit ratio for this patient population.

KEY POINTS

  • CABG is considered the standard of care for patients with intermediate or high coronary artery disease burden.
  • Traditional CABG performed via median sternotomy with the use of cardiopulmonary bypass is the technical standard for surgical coronary revascularization.
  • Suturing the left internal mammary artery directly to the left anterior descending artery is the most effective technique for coronary revascularization.
  • Minimally invasive approaches to CABG are safe and effective alternatives in select patient populations.


 

References

The evolution of coronary artery bypass grafting (CABG) has been a key component in significantly reducing the morbidity and mortality associated with occlusive coronary artery disease (CAD). Cleveland Clinic surgeons, through their technical interventions and innovations, have led the evolution in coronary revascularization starting in the 1960s and continuing today. This article provides a brief overview of the evolution and describes the issues associated with current CABG approaches.

EARLY WORK IN RECONSTRUCTIVE CORONARY ARTERY SURGERY

Results from the first large series of venous grafting for CAD were reported in 1970 by Favaloro and colleagues at Cleveland Clinic. 1 They showed the efficacy of grafting in treating CAD, with low associated morbidity and mortality, thus establishing this surgery as the treatment modality for CAD.

The technique of surgical myocardial revascularization was a culmination of developments that began years earlier with the Vineberg procedure, involving suturing of the mammary artery to the muscle rather than a vessel-to-vessel anastomosis. From this followed the coronary patch, end-to-end bypass, and then end-to-side bypass.

In the 1970s, the refinement of suturing the left internal mammary artery (LIMA) directly to the left anterior descending (LAD) artery using magnifying loops was pioneered and popularized at Cleveland Clinic. This later became the cornerstone of future coronary revascularizations.

As a direct result of the successful technical advances and excellent clinical outcomes, the volume of CABG procedures in the United States rose steadily during the 1980s and reached its peak in 1995. It then began a slow decline that continued until 2013, when the trend began to reverse. It was still rising through 2015.

WHY THE RENEWED INTEREST IN CABG?

A key component to continued use of CABG is that it appears to have a clinical edge over other treatments. This has been shown in several high-profile studies: SYNTAX, 2,3 FREEDOM, 4,5 BEST, 6 and NOBLE. 7 For example, in the SYNTAX trial, which compared CABG vs percutaneous coronary intervention (PCI), the conclusion from both the 1-year 2 and the 5-year 3 results was that CABG should remain the standard of care for patients with complex lesions—those with an intermediate or high burden of CAD.

The 5-year outcomes showed that the rate of major adverse cardiac and cerebrovascular events favored CABG over PCI (26.9% vs 37.3%, respectively; P < .0001). 3 All-cause mortality, although not statistically significant, also was better for CABG (11.4% vs 13.9%). This indicates that as the complexity and burden of disease increase, the benefit of CABG over PCI becomes more prominent. In short, the worse the disease, the better the results with CABG.

Why is CABG better?

One rationale is that CABG not only bypasses the culprit-lesion vessel, it also protects against future lesions. An elegant study published in 2010 showed that in most cases of acute myocardial infarction (MI), the culprit coronary lesion is in the first 7 cm of the LAD. 8 With CABG, most distal anastomoses are beyond 7 cm and, thus, are beyond the location of the vast majority of potential future culprit lesions.

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