Lower 10-Year Mortality With Multiple Arterial CABG in Diabetes: ART

Multiple arterial grafting is linked to lower mortality at 10 years after CABG in patients with diabetes compared with a single arterial grafting approach, according to a post hoc analysis of the Arterial Revascularization Trial (ART).

The findings are in contrast with what was observed in the trial’s main intention-to-treat results, which showed no benefit for bilateral internal-thoracic artery (ITA) grafts over a strategy of a single arterial graft, plus vein or radial artery grafts, in a population of all-comers. However, with a high rate of crossover in the original trial and a range of surgeon experience levels, as-treated analyses did suggest better outcomes with multiple grafts, especially in expert hands.

Lead author David Taggart, MD, PhD (University of Oxford, England), told TCTMD he was “pleasantly surprised” with what this analysis showed.

“We've always believed that patients with diabetes have more-severe coronary artery disease and therefore the potential of arteries to be of greater benefit would be intuitive,” he said. “Of course, the patients were clearly not randomized to diabetes or not. But when we looked at the outcomes, we saw that overall, the use of multiple arterial grafts is beneficial in all patients, but the effect was even greater in patients with diabetes. And that would be intuitive in the sense that patients with diabetes tend to have more-generalized endothelial dysfunction and usually have more-severe coronary artery disease.”

Commenting on the findings for TCTMD, Faisal Bakaeen, MD (Cleveland Clinic, OH), told TCTMD that multiple arterial grafting is standard of care at his high-volume institution. However, he said, “multiarterial grafting is not for every patient and is also not for every surgeon. In terms of selecting patients appropriately, you have to make sure that the risk-benefit ratio is there and . . . know that in your hands you're going to achieve a good outcome.”

As much as he believes in the superiority of using multiple arterial grafts, for now the data can’t necessarily be put into practice, according to Bakaeen, especially for the surgeon who is inexperienced in this more-complex procedure. “We feel that the diabetic [patients] would benefit in particular with this approach because of the aggressiveness of the disease and the diffuseness of it, and we believe that the ITAs would be resistant in the long run to atherosclerosis, but again this is all hypothesis-generating,” he said.

Diabetic Subanalysis

For the analysis, published online this month in the European Heart Journal, Taggart and colleagues included data from 3,020 patients in ART, of which 23.7% had diabetes.

In the 55.8% of the patients without diabetes and 56.6% of with diabetes who received multiple arterial grafting, 10-year mortality (primary endpoint) and MACE (secondary composite endpoint, defined as death, MI, and stroke) were each lower compared with those who only received single arterial grafts.

10-Year Outcomes by Arterial Grafting Strategy

Deep sternal wound infections were an uncommon complication but occurred more frequently in those who received multiple compared with single arterial grafts in both the diabetic (7.9% vs 4.8%) and nondiabetic cohorts (3.3% vs 2.1%). The highest rates of deep sternal wound infections were observed in insulin-treated diabetic patients receiving multiple versus single arterial grafting (9.6% vs 6.3%).

Taggart said this result wasn’t unexpected because “there are certain patient groups where the risk is higher, [including] the obese diabetic patient, obese females, and patients with bad lungs. They tend to spend a longer time on ventilators,” he explained.

Further, Bakaeen said that there is a “spectrum” of deep sternal wound infections. On one end of that spectrum are those “where you could just put a wound vac [on] and put them on antibiotics and the patient recovers with minimal long-term impact on their physical appearance and ability and quality of life and psyche,” while on the other side are cases that are “devastating [and] destructive . . .  where you have to take them to OR, resect their sternum, do a radical debridement, and then have plastic reconstructions, which would leave them with essentially a deformity and lasting scars, psychological and physical.” The latter are rarer, he said, adding that “most deep sternal wound infection is now an amenable to more-conservative approach.”

Call for More Arterial Grafts

The impact of surgeon experience with multiple arterial grafting is still debated, though most believe there is a strong link with outcomes. In ART, there was a clear association of surgeon volume with crossover rate, according to Taggart.

“We know that if you use an arterial graft well, that will do the patient very well over the longer term,” he said. “On the other hand, a poor artery is worse than a good vein graft. If you cannot harvest the artery properly or deploy it properly, then it's not a great option for the patient despite the biological rationale for it. It's got to be done by someone who knows what they're doing.”

However, with many CABG centers only performing “50 to 100 cases a year by two or three surgeons, it's very hard for them to give the individual experience on such small numbers to build up an appropriate experience,” Taggart added.

At this point, Taggart said there is enough published data to support multiple arterial grafts becoming standard CABG practice both for diabetic patients and the general population. “Most people believe multiple arterial grafts are better for you because we know that their patency out to 10 years is far superior to vein grafts,” he said. “A lot of people were disappointed in the ART trial because it didn't prove that that was the case, but the problem with the ART trial was it was confounded by lots of crossovers, lots of use of radial [instead of mammary] arteries, [and] very high use of optimal medical therapies.”

Designed more than 20 years ago, ART is not reflective of current practice, he continued. “We're still hopeful that we will see an effect with a longer follow-up of the benefit of these grafts,” Taggart said, adding that he expects the 15-year data to be published soon.

As surgeons await more-definitive answers from the ROMA trial, Bakaeen said they are certainly talking about multiple arterial grafting more, but case numbers “have been relatively flat over the last 10 years. There's a suggestion or hint that they're beginning to pick up, especially for radial arteries, but it's just very subtle right now.”

Taggart said he’d like to see surgeons become more confident in using multiple arterial grafts so they could use the strategy more, especially in those more likely to benefit like younger patients, those with diabetes, and patients with more severe coronary disease. “The problem as well is that there's no real initiative to push the use of more arterial grafts,” he said, adding that groups like the American Association for Thoracic Surgery and Society of Thoracic Surgeons “should gradually try to recommend an increase in the number of arterial grafts.”