Five major international cardiothoracic professional associations have endorsed European guidelines for the management of chronic coronary syndromes in an unprecedented move.
Writing about the 'remarkable development' in JAMA Surgery, Faisal Bakaeen and Torsten Doenst say the American Association for Thoracic Surgery (AATS), Society of Thoracic Surgeons (STS), European Association for Cardio-Thoracic Surgery (EACTS), Latin American Association of Cardiac and Endovascular Surgery (LACES), and the Asian Society for Cardiovascular and Thoracic Surgery (ASCVTS) – have endorsed the 2024 European Society of Cardiology (ESC) guideline for the management of chronic coronary syndromes.
This endorsement is significant and unprecedented. It marks the first time all major international cardiothoracic surgical associations have spoken collectively in one voice about guideline recommendations.
It is also the first time that the North American surgical associations have broken ranks with their cardiology counterparts about what is customarily a collaborative guideline.
The surgical associations have clearly explained their rationale for endorsing the ESC guideline while rejecting that of American College of Cardiology (ACC), American Heart Association (AHA), and Society of Cardiovascular Angiography and Interventions (SCAI) guideline in 2021, and it centres on synthesis and interpretation of the evidence that was used to inform the recommendations.
The root of the difference between the North American and European coronary guideline recommendations is that the former dismissed older trials that showed a survival advantage of CABG over medical therapy in patients with chronic multi-vessel coronary artery disease regardless of left ventricular function and chose to base their recommendations on newer trials.
However, not a single one of those newer trials actually randomised patients with multi-vessel disease between medical therapy vs CABG.
Importantly, the International Study of Comparative Health Effectiveness with Medical and Invasive Approaches (ISCHAEMIA) study was misconstrued as relevant comparative evidence between CABG and medical therapy. Therefore, the CABG downgrade in patients with multi-vessel disease and normal ejection fraction from class I (is recommended) to class IIb (may be considered/uncertain benefit) was never based on randomised trials, and the level of evidence B-Randomised was therefore an inappropriate designation by the 2021 ACC/AHA/SCAI guidelines.
In addition, the citations to support the downgrade of CABG in patients with an ejection fraction of 35% to 50% from class I to class IIa (reasonable) clearly favoured CABG over medical therapy.
On the other hand, the ESC guidelines approached patients with multi-vessel disease looking at an umbrella of clinical outcomes that included overall survival, cardiovascular mortality, and spontaneous myocardial infarction, and supported a class I indication for revascularisation based on evidence that supported all of the individual outcome components in patients both with ejection fraction up to 35% or greater.
Revascularisation for single- or 2-vessel coronary artery disease involving the left anterior descending artery in patients with ejection fraction greater than 35% was a class I recommendation to reduce long-term cardiovascular mortality and spontaneous myocardial infarction.
Regarding the revascularisation modality, CABG was class I over percutaneous coronary intervention (PCI) except in high-risk surgical patients or in patients without diabetes with low-to-moderate complexity of coronary disease in whom PCI can provide similar completeness of revascularisation to CABG.
In addition to emphasising the importance of multidisciplinary team discussion and patient preference, the ESC guidelines went a step further than the ACC/AHA/SCAI guideline by discouraging ad hoc PCI.
This is a crucial message that can curb the potential overuse of PCI under the premise that the patient is already on the catheterisation table (i.e, a 1-stop shop) without giving consideration to heart-team deliberations, disease complexity, durability of intervention, and patient priorities.
The multi-societal surgical endorsement lauded the multidisciplinary and collaborative nature of the ESC guidelines, which were extensively vetted with diverse, multinational representation by professional cardiac societies from 53 countries.
As with other life-threatening disease entities with different treatment options, modern-day management of coronary artery disease is managed with a multidisciplinary approach, an approach that gets a class I recommendation by both the European and US guidelines.
The European guidelines valued and implemented this multidisciplinary collaboration by including expert surgeons in the authorship and review teams.
In contrast, the recent 2023 AHA/ACC guideline for the management of patients with chronic coronary disease did not include a single surgeon author because it perpetuated the 2021 recommendations without an opportunity to re-examine the evidence and recalibrate the recommendations.
There is ample contemporary evidence comparing CABG with PCI in patients with multi-vessel coronary artery disease, but there are no recent randomised trials comparing CABG vs medical therapy only in this patient cohort.
This is a potential limitation of the evidence and not necessarily an annulment of older evidence that clearly supports a class I recommendation for CABG to improve survival in patients with stable multi-vessel coronary artery disease.
Only new and relevant trials can dispute or annul such evidence. ISCHAEMIA was not that trial, but is such a trial feasible or necessary?
A trial comparing CABG to medical therapy with survival as an end point would require thousands of patients and a five- to-10-year follow-up. Funding for such a resource intensive and expensive trial would be challenging.
There will be little appetite for industry support because no commercial devices are used, and the CABG population is a very small slice of the pie of patients with atherosclerotic disease who are a target market for cardiovascular pharmaceuticals.
Enrolment would also be a challenge, given the lack of equipoise among surgeons and cardiologists who understand the pathophysiology of coronary artery disease, its natural history, and how it can be modified by surgical collateralisation.
The latter offers both a therapeutic and a prophylactic intervention in one, which explains the efficacy and durability of CABG, especially in patients with complex coronary artery disease. This advantage of CABG cannot be matched by stents or any currently available medicine.
As long as patients with high risk for myocardial infarction from complex coronary disease are alive, CABG will be an additive treatment option for preventing future infarctions and thereby potentially prolonging life.
Nevertheless, revascularisation trials that inform the guidelines must focus on outcomes that matter and have external validity. Survival is clearly the most objective and important end point, but major adverse cardiovascular events are important and extensively validated disease specific end points.
There is also increasing interest now in other outcome measures, such as quality of life. However, assessment of quality of life is an imperfect science especially in trials that include a surgical arm where blinding is impossible and where the benefit may be delayed until after full surgical recovery.
Regarding the external validity of trials, the litmus test is how similar are the enrolled patients to the average patients we see and treat in our daily practice?
Most revascularisation trials focus on patients with lower atherosclerotic burden and those with less complex coronary artery disease, yet their results are extrapolated to inform CABG recommendations.
Even in the Synergy Between PCI with TAXUS and Cardiac Surgery (SYNTAX) trial, which enrolled patients with 3-vessel and left main coronary artery disease, more than 35% of patients were assigned to the CABG-nested registry because PCI was not feasible or did not achieve equipoise with CABG.
In summary, the international surgical endorsement of the 2024 ESC guidelines for the management of chronic coronary syndromes prioritised robust and extensively vetted evidence over traditional geomedical professional societal alignment when it comes to clinical guideline documents.
To be clear, until recently, this societal alignment has always been in harmony with scientific facts and consensus opinion when the science is uncertain. After careful study and analysis, the surgical community has supported what it believes are the best evidence-based recommendations for the current management of patients with chronic coronary artery disease.
This is important for our patients and all stakeholders involved in their care because it eliminates doubts and uncertainties in cardiovascular care and optimises clinical outcomes.
Faisal Bakaeen MD – Coronary Centre, Department of Thoracic and Cardiovascular Surgery, Miller Family Heart, Vascular & Thoracic Institute, Cleveland Clinic, Ohio;
Torsten Doenst MD PhD – Department of Cardiothoracic Surgery, University Hospital Jena, Germany.
JAMA Surgery article – Two Guidelines on Coronary Disease and the Atlantic Divide (Open access)
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