Elderly CABG Patients Stand to Benefit From Artery-Only Strategy

Relying entirely on arteries as a source for grafts in CABG appears to impart better survival for patients irrespective of age, according to a new analysis of registry data from Australia and New Zealand.

Its authors point to prior studies showing that the strategy, known as total arterial revascularization (TAR), offers better long-term outcomes than more-traditional CABG using a single left internal mammary artery to the left anterior descending artery, with saphenous vein grafts (SVGs) as needed. Additionally, arterial conduits are more durable and more resistant to atherosclerosis in comparison to vein grafts.

Yet the field for the most part has been slow to embrace TAR in elderly adults—an increasingly large portion of the CABG population—due to worries that the technique might be too complex and their lifespans too short to fully benefit, the investigators say.

“In Australia, uptake of TAR [is] greater than the rest of the world, approximating tenfold higher than is typical internationally,” senior author Alistair Royse, MBBS, MD (Royal Melbourne Hospital, Australia, and Universiti Kebangsaan Malaysia, Kuala Lumpur), told TCTMD. That experience presents a unique opportunity to have the statistical power to assess outcomes for the elderly subgroup.

“This analysis found that the benefit of TAR persisted in patients over 70 years old and that age should not be a barrier to the use of TAR,” he wrote via email.

Additionally, said Royse, their study investigated outcomes of mixed procedures. “It’s often assumed that multiple arterial grafting yields similar outcomes to TAR, even when vein grafts are included,” he said, but in this dataset TAR was the superior option. “Even limited use of veins appears to diminish the long-term benefits of an all-arterial approach.”

Society of Thoracic Surgeons (STS) President Joseph Sabik III, MD (University Hospitals Cleveland Medical Center, OH), whose own research has shown positive results with an arterial approach to CABG, told TCTMD that the new analysis, while observational, is useful in that it comes from multiple centers spanning two countries.

Notably, the researchers looked not just at TAR cases but also at different groups where some grafts were arterial, but not all. “It was very interesting in that they see this stepwise improvement,” he said, adding that it appears having some vein grafts in the mix is not as good as TAR.

The study is a continuation of the “overwhelming evidence showing that arterial grafting is better than venous grafting. The more arterial grafts, the better. The less venous grafts, the better,” said Sabik.

“As a profession we need to use more arterial grafts, and I think this paper points us in that direction,” he said, noting that in the STS database, “only 16% of patients are getting two arterial grafts.”

ANZSCTS Registry Data

The study, led by Justin Ren, PhD (Royal Melbourne Hospital), was published recently in JACC: Advances.

Ren, Royse, and colleagues used the Australian and New Zealand Society of Cardiac and Thoracic Surgeons (ANZSCTS) registry to identify 59,641 patients who underwent primary isolated CABG with at least two grafts between 2001 and 2020. Among them, 63% were younger than 70 at the time of their surgery and 37% were age 70 or older.

TAR was used in 32% of the younger group, with the remainder receiving at least one saphenous vein graft. In the older group, 24% were treated using TAR.

An artery-only approach was associated with better survival in both the older and younger groups.

Survival After CABG Surgery: TAR vs Non-TAR

For both younger and older patients, survival was highest for individuals in whom no vein grafts were used, followed by those receiving at least one SVG plus multiple arterial grafts and those who got at least one SVG plus a single arterial graft. In the elderly group, the hazard ratios were 0.86 (95% CI 0.80-0.93) and 0.78 (0.73-0.84) for multiple and single arterial grafts, respectively, compared with TAR.

“These findings challenge the assumption that limited life expectancy precludes arterial grafting and support broader implementation of TAR in appropriately selected older patients,” the authors conclude.

Doable and Possible

To TCTMD, Royse explained that the “rationale of TAR is predicated on avoiding the conduit that is known to have a definite and predictable failure over time, which is the vein graft.” Late failure of CABG is primarily driven by failure of vein grafts, he added, noting that arterial conduits, if they fail, would do so early rather than late and would be due to flow competition.

Royse said at least half of today’s CABG surgeries could be done simply by substituting an arterial conduit in place of a vein, without changing any other techniques. Sequential grafting, he said, could enable even more CABG to be done as TAR. “However, for routine TAR approximating 100% [of cases], reliance on complex and composite grafting would be required for some patients,” which would necessitate surgeons learning new skills, he acknowledged.

For surgeons early in their TAR experience, patient selection “should be more conservative,” Royse advised. “Nevertheless, most surgeons could perform TAR in the majority of their patients with minimal changes to their personal, institutional, and perioperative techniques or methods. Our various analyses of large-scale registry data have not identified any subset of patients in which TAR is not associated with superior survival. This includes individuals with diabetes, females, and older patients.”

Sabik agreed that, for most surgeons, TAR is doable and possible in most patients.  “There’s a lot of techniques that many of us have become very comfortable with, such as sequential grafting [and] composite grafting. . . .  So you can use a radial artery, for instance, and do two, three, maybe even more grafts with it. You can use a free mammary [artery] in the same way.”

That said, some may have issues that make TAR less attainable, he noted. For example, patients with diabetes and overweight are more vulnerable to having sternal wound complications. Also, for 10% of the population, the radial artery is the primary source of blood supply to the hand, making it impossible to remove that vessel for use as a conduit, and frailty can be a barrier. The key, Sabik advised, is “tailoring the operation to the patient.”

Going forward, said Sabik, the ROMA trial will provide more data in this area. “I think that’s going to be helpful, [because there are many] people who just don’t believe observational studies and really rely on more randomized studies,” he noted.

Also, the ongoing TA Trial, a randomized comparison of TAR versus arterial CABG with at least one SVG conduit, “will be very informative,” Royse predicted. The researchers are also conducting a Bayesian meta-analysis and plan to analyze additional registry data to assess late outcomes.