Closing the gap between best evidence and common practice in surgical coronary revascularization: The rationale for superspecialization

In an effort to improve outcomes for patients with valvular heart disease, there has been a concerted push over the past decade toward the creation of “Heart Valve Centers” or “Heart Valve Reference Centers.” In 2017 the European Society of Cardiology and European Association for Cardiothoracic Surgery even jointly published a document outlining the standards that would define such a center . The same year, six North American professional organizations preeminent in the fields of Cardiac Surgery, Interventional Cardiology, Anesthesiology and Echocardiography published a Systems of Care Document, entitled A Proposal to Optimize Care for Patients with Valvular Heart Disease . These same organizations recently published an update , stating that their document was necessary because “providing optimal care to patients with valvular heart disease is an increasingly complex process, starting with early recognition and diagnosis … MDT assessment, shared decision-making, and long-term follow-up.” They also note, “there are an increasing number of treatment options available to patients with valvular heart disease; yet not all patients are aware of or have access to the full spectrum of interventions.” The authors go on to propose an improved system of care for patients at valvular heart disease centers, whose primary goal is to optimize outcomes for all patients. They argue that the “case for centers with the ability to offer more comprehensive care is logical.” The authors state their intent is “to set performance and quality goals for a valve center to meet benchmarks to be considered either comprehensive or primary in a manner that would be more objective than simple self-designation.”

There are few who would argue with such sentiments, motivation, and logic. Of course, that then begs the question: why do the same statements not also apply equally well to patients with ischemic heart disease? Yet the stark reality is that no similar joint multinational or multidisciplinary proposal has ever been undertaken or even suggested for patients with ischemic heart disease. This is truly remarkable and counterintuitive, especially considering that vastly more patients in the developed world undergo procedures to treat coronary artery disease than valvular heart disease.

Although the 2014 ESC/EACTS guidelines on myocardial revascularization recommend to “perform [CABG] procedures in a hospital structure and by a team specialized in cardiac surgery, using written protocols” (Class I, LOE B), they stop well short of recommending any special training, team, or focus on surgical coronary revascularization.

The STS Adult Cardiac Surgery Database 2019 update on outcomes and quality makes clear that the majority of all adult cardiac surgical procedures performed in North America is isolated coronary artery bypass grafting (CABG) (55%), while CABG plus mitral valve (MV) or aortic valve (AV) procedures comprise an additional 8% of all procedures; thus while isolated MV or AV procedures cumulatively account for 16% of all procedures, CABG makes up 63% of all procedures recorded in the contemporary STS database.

Not only does CABG make up the large majority of all procedures performed by adult cardiac surgeons but also it continues to be performed by much the same techniques that were developed 40 years ago. Full sternotomy with aortic cannulation and clamping for cardioplegic arrest and bypass with a single internal thoracic artery graft to the left anterior descending coronary artery plus reversed saphenous vein grafts (SVGs) to all non-left anterior descending (LAD) coronary targets, remaining the most commonly performed procedure in cardiothoracic surgery. While this is an excellent and well-proven option for many patients, it does not mean that it is the best option for all patients. It ignores the fact that aortic manipulation is the single most important contributor to perioperative stroke and that SVGs have >50% rate of failure at 10 years.

For more than three decades it has been repeatedly demonstrated that arterial grafts have much superior angiographic patency rates when compared to vein grafts over the long term. Numerous authors have reported superior survival, major adverse cardiovascular events-free survival, and intervention-free survival with multiple arterial conduits compared to a single internal thoracic artery (ITA)-LAD graft plus SVGs, since the seminal report by Lytle et al. .

This has been shown to be true even in diabetic patients, in whom the provision of bilateral internal thoracic arteries (BITA) grafting rather than single internal thoracic artery (SITA) grafting confers a greater survival benefit than SITA grafting in nondiabetic patients . Despite these compelling data, the use of bilateral ITA grafting remains less than 6% in the United States .

An insightful analysis of intraoperative conversion from planned BITA to SITA grafting in the arterial revascularization trial (ART) suggests that even self-selected surgeons have highly variable expertise in deploying BITA conduits, despite having performed a large number of CABG procedures in their careers. In this report the overall rate of unintentional conversion from BITA to SITA was 14% and ranged from 0% to 100% among individual surgeons and 0%–49% for individual surgical centers . In the ART trial, patients who actually received more than one arterial conduit enjoyed significantly better 10 years survival and a significantly lower incidence of death/myocardial infarction/stroke than those who received a single arterial conduit .

Gaudino and colleagues reported a metaanalysis of pooled patient-level data from six previous prospective randomized trials comparing outcomes after CABG with LITA-LAD plus SVGs (single arterial conduit) versus LITA-LAD plus at least one radial artery graft (multiple arterial conduits). This dataset confirmed that death/myocardial infarction/repeat revascularization was less frequent when a radial artery graft was included (typically grafted to the second most important coronary target), driven by a significant reduction in graft failure among radial conduits . Ten-year follow-up of these same patients has yielded similar findings with the continued divergence of these curves in favor of multiple arterial grafting . Despite this and many other reports of superior graft patency and improved clinical outcomes with radial artery grafting, less than 7% of isolated CABG cases in the United States currently include a radial artery conduit .

The combination of BITA grafting and radial artery grafting allows total arterial revascularization (TAR), which has been shown to confer a long-term benefit in terms of symptom relief and survival . Regrettably, TAR accounts for approximately 1%–2% of all multivessel CABG procedures worldwide.

The evidence that minimizing aortic manipulation can significantly reduce the incidence of stroke has been well documented over decades of practice. Most recently, Zhao and colleagues reported a network metaanalysis of 13 studies, including 37,720 patients, comparing outcomes with four alternative CABG techniques, namely, traditional on-pump CABG, off-pump CABG (OPCAB) with a partial aortic clamp for proximal anastomoses, OPCAB with a clampless facilitating device for proximal anastomoses, and OPCAB with a no-aortic-touch (an-aortic) technique in which all graft inflow was from in situ BITA conduits. They reported that an-aortic OPCAB was associated with a hazard ratio of 0.22 for stroke, 0.50 for mortality, 0.73 for myocardial infarction, compared to traditional CABG. Indeed, the relative risk of virtually every adverse event correlated with the extent of aortic manipulation in the surgical technique chosen as shown in Fig. 1.1 . Perhaps due to the technical challenges that this surgical strategy entails, aortic TAR accounts for <1% of all CABG procedures worldwide.

Apr 6, 2024 | Posted by in CARDIOLOGY | Comments Off on Closing the gap between best evidence and common practice in surgical coronary revascularization: The rationale for superspecialization

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