The never-ending story: on-pump and off-pump coronary artery bypass grafting versus percutaneous coronary intervention and long-term survival

European clinical practice guidelines support that coronary artery bypass graft (CABG) surgery is the treatment of choice for patients with triple-vessel and left main coronary artery disease, in patients with complex coronary artery disease according to the SYNTAX score, in diabetics and in those with poor left ventricular function [1]. The benefits of CABG are well established in specific subsets of patients, although substantial and acrimonious debate has populated medical and non-medical literature and has been an integral part of multiple discussions in all sorts of professional gatherings [2, 3].

Since the pioneering work of Favaloro [4] and others, CABG has evolved into a gold standard of therapy and continues to evolve. Additional surgical debate is still ongoing regarding the performance of the operation with the use of cardiopulmonary bypass or selecting the off-pump approach; however, most studies on the latter have limited follow-up not longer than 5 years [5]. With regard to the use of conduits for revascularization, it is out of doubt and discussion that using the left internal mammary artery or internal thoracic artery depending on the taste of each is the way to go. This is supported by a myriad of studies [6]. On the other hand, the multiple/complete arterial revascularization strategy is also a matter of controversy and analysis. Recent information supports the need for an increasing usage of this strategy, which has to be adapted to the patient [7, 8].

Percutaneous coronary intervention (PCI) introduced by Grüntzig in the form of percutaneous transluminal coronary angioplasty represented a major step forward in the treatment of coronary artery disease and had an impact on how the community treats specific subsets of patients and on the rate of surgical myocardial revascularization [9]. Regardless of how radically and even violently cardiologists and surgeons defend their individual and collective stances, CABG and PCI have specific indications and are out there to work for the benefit of the patient, not for the benefit of the one performing them. And this should be our ultimate goal.

In this issue of the Journal, Kageyama et al. [10], a selected group of prestigious cardiologists and surgeons, aimed at investigating the impact of on-pump and off-pump CABG versus PCI on 10-year all-cause mortality of the 1800 patients with three-vessel and/or left main disease randomized at the SYNTAXES trial. Three major strategies were compared: on-pump CABG (n = 725), off-pump CABG (n = 128) and PCI (n = 903). After adjusting for the 9 variables included, the authors conclude by saying that in the SYNTAXES trial, 10-year mortality adjusted for major confounders was significantly lower following on-pump CABG compared to PCI, whilst off-pump CABG offered no prognostic survival benefit over PCI; however, there were issues with a smaller off-pump sample size to perform the same statistical comparison. Furthermore, the described differences among surgical groups including but not limited to the number of arterial grafts and periprocedural outcomes such as the surprising absence of stroke in the off-pump group are to be noticed. If despite of randomization inclusion bias were present this has to be considered.

Important is that authors recognize some limitations of off-pump CABG for appropriate myocardial revascularization in the long term, 10 years. Every study published confirms that off-pump CABG is associated with a lesser extent of myocardial revascularization due to a lesser number of grafts. Many would appropriately argue that surgical experience may play a role in outcomes. Second, that all-cause mortality is not necessarily related to revascularization. After 10 years, patients have multiple causes of death that have never been approached appropriately. The actual causes of death must always be well described and confirmed, even though we agree that accurate collection of follow-up data may be challenging. Crude mortality, widely accepted by the community, may not necessarily be the best way to report mortality, despite any statistical manipulation.

In the discussion, authors address something well known, that a given stent was in use at the time of the study. Newer generations of stents might have led to different results in the PCI arm. This is how it works, and the community will never, for sure, know how different results are working overtime as stents are changing frequently and ‘older’ stents are therefore no longer followed, although recent trends suggest controversial outcomes as well [9].

This submission is relevant and important as it brings to the public what we know for ages, that on-pump surgery is the gold standard for triple-vessel and LMCA and that it performs better than PCI in this regard. The comparative similar performance of off-pump versus PCI at 10 years will probably need a finer analysis due to confounders and differences in procedural conduct.

Institutional Review Board (IRB)

IRB approval was not required for this commentary.

Conflict of interest: Carlos-A. Mestres discloses the following: Consulting fees Edwards Clinical Events Committee (CEC) and Cytosorbents Corp. The other author has nothing to disclose.

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