Decades of Real-world Data Affirm Benefit of Multiple Arterial CABG

Not only does the type of coronary artery conduit used in CABG affect long-term survival but use of multiple arterial grafting increases life span the most, according to two analyses of real-world outcomes from two surgeons.

It is widely known that multiple arterial grafting is associated with better outcomes after CABG compared with vein grafting, yet use of this technique has not increased in recent years. Experts have cited increased technical difficulty and a learning curve as barriers to widespread adoption.

“It's like building a Rolls-Royce instead of building a Ford,” Aziz Momin, MBBS, MD (St George’s Hospital, London, England), who presented the data at the Society of Thoracic Surgeons (STS) 2022 annual meeting, told TCTMD. “The patient will do a lot better in the longer term. And if we want to compete with the cardiologists and stents, we have to give them an operation with arterial grafts, which will increase life span. Really the take-home message is we should be increasing our arterial grafting.”

Too often, CABG as it’s performed today is “the same as it was in 1975,” John D. Puskas, MD (Mount Sinai Beth Israel, Mount Sinai Morningside, New York, NY), who was not involved in the study, told TCTMD. “We as a profession need to treat coronary surgery as a subspecialty [with] surgeons who are committed to excellence in coronary surgery, including multiple arterial grafting, doing the coronary surgery. We should expect that coronary surgery should evolve over time and not be almost indistinguishable from the same surgery that our mentors' mentors performed.”

More Arteries, Better Outcomes

Momin gave two presentations both looking at all 2,979 consecutive patients (mean age 67; 80.9% men) who underwent isolated CABG performed by him or his colleague Venkatachalam Chandrasekaran, MBBS (St George’s Hospital) between April 1999 and March 2020. In total, 61.5% of patients underwent off-pump procedures, 34.3% had total arterial revascularization, 61.7% had arterial and saphenous vein revascularization, and 4.0% received only saphenous vein grafts.

For the first study, presented last Saturday, Momin showed the longest mean survival in the group of patients who received total arterial revascularization (18.7 years) followed by a significantly decreased survival of 16.1 years in the group who received traditional single internal mammary artery (SIMA) and saphenous vein grafts. Those who received only vein grafts had the worst survival of only 10.4 years (P < 0.00001 for all).

If we want to compete with the cardiologists and stents, we have to give them an operation with arterial grafts, which will increase life span. Aziz Momin

In the second analysis, which won the J. Maxwell Chamberlain Memorial Paper award at the meeting and was presented last Sunday, Momin and Chandrasekaran stratified the patients into four groups: total arterial revascularization with bilateral internal mammary arteries (BIMA) plus/minus radial artery (n = 431), SIMA plus radial artery plus/minus saphenous vein (n = 823), SIMA plus/minus saphenous vein with no radial artery grafting (n = 1,565), only radial artery plus/minus saphenous vein grafting (n = 160).

Again, the group receiving total arterial revascularization had the best long-term mean survival (18.65 years), although this was closely followed by the mixed SIMA and radial artery grafting group (18.60 years). Survival was lowest in those who received SIMA without radial artery grafting (15.86 years) and no IMA grafting (10.99 years). The BIMA strategy performed significantly better than all other strategies with the exception of SIMA plus radial grafting with regards to long-term survival in this cohort (P < 0.00001 for all).

Learning From Observational Data

Discussing the second study, Marc Ruel, MD, MPH (University of Ottawa Heart Institute, Canada), pointed out that the rate of multiple arterial grafting in this population “compares favorably to the STS national database average,” but asked whether the combination of off-pump CABG and use of multiple vein grafts and a single arterial graft may have led to worse outcomes in those patients, and whether underuse of dual antiplatelet therapy could have led to worse outcomes.

Momin stressed that the findings show the “evolution of two surgeons” over time, with both of them initially selecting patients to receive total arterial grafting. “With experience and skill sets, we now tend to try and use it as a default for most patients,” he said, estimating that their rate “must be over 50% to 60%” in recent years.

Also, he explained that while he defaults to on-pump surgeries, Chandrasekaran prefers off-pump. However, Momin said, “we tailor the operation to the patient and the coronary anatomy and what we find intraoperatively. Our default is always to use two mammaries or a mammary plus another radial on the left side, but we will do what's required.”

As for antiplatelet therapy, this would likely make a “big difference” in patients receiving vein grafts, but not so much in those receiving arterial grafts.

Puskas said there are two barriers that are keeping multiple arterial grafting from being performed more often. The first relates to the lack of randomized data showing benefits, although this will hopefully be remedied by the ongoing ROMA trial, he said, predicting it will show increased survival following multiple arterial grafting. Still, he said he would like to see more observational studies like these. “I think that we can learn things from observational data,” Puskas said. “You don't need to do a randomized trial to prove that a parachute is a good thing when jumping out of an airplane.”

Secondly, he acknowledged that multiple arterial grafting is harder to do and can be associated with increased complications like deep sternal wound infections, especially if the grafts are harvested in the standard way and not using the less-traumatic skeletonized method, which is when the veins, muscle, and fascia are left on the chest wall. This is a “less-excusable” reason for not performing multiple arterial grafting, Puskas said, even though “it's technically much more demanding, it takes more time, and you're not paid any more money.”

Momin said, “If you don't want to use two arteries from the chest, because people are worried about sternal wound complications and so forth, you can also always use one artery from the chest and one artery from the arm and put them on the left side of the heart, and you'll get near enough as much benefit.” He added that their rate of deep sternal wound complications has been less than 0.5%.

“Not only is it hard to teach harvesting, the skeletonization, in training, but you also have to teach where to put the second arterial graft,” observed Jennifer Lawton, MD (Johns Hopkins University, Baltimore, MD), who co-moderated the Saturday session. “You always have to change your plan intraoperatively to make the most of the arterial conduit.”

To increase the rate of multiple arterial grafting moving forward, Puskas called for STS to first make it a quality metric for CABG and also for the US Centers for Medicare & Medicaid Services to “fund a second arterial graft in a meaningful way because it saves lives, prevents heart attacks [and] hospital readmissions, and in the end, is cost-effective.”

Education will also be key. Momin said he would like to see international training programs in which residents and fellows can learn how to do arterial grafting, adding that “it should be a subspeciality like mitral valve surgery or like aortic surgery.”