From the Journals

SYNTAX: Early CABG results with arterial grafts similar to venous in matched groups

Key clinical point: Surgeons should choose arterial grafts for multigraft coronary artery bypass surgery when feasible.

Major finding: Patients who received multiple arterial graft had significantly lower rates of death and other problems than did those who received venous grafts in unmatched groups, but results were similar between propensity matched groups.

Data source: Registry of 1,322 patients who had 5-year follow-up after coronary artery bypass surgery within the SYNTAX trial.

Disclosures: Boston Scientific supported the trial. Coauthor Keith Dawkins is employed by Boston Scientific and coauthor Ted Feldman has received consulting fees from the company. The other authors reported no disclosures.

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Stay the arterial graft course

That arterial grafts are a better long-term match in coronary bypass surgery has been a tenet in cardiac surgery, but multiple factors have prevented their more widespread acceptance, Dr. Davis C. Drinkwater Jr. said in his invited commentary (J Thorac Cardiovasc Surg. 2015.doi:10.1016/j.jtcvs.2015.06.014). Concerns about sternal wound healing, particularly in diabetic or obese patients, as well as the alternative generally good early and mid-term results in multivessel coronary artery disease using the left internal thoracic artery to LAD accompanied by saphenous vein grafts, have made surgeons hesitant to take up the approach more readily, said Dr. Drinkwater of Frist Cardiology, Tristar Centennial Medical Center, Nashville, Tenn.

The SYNTAX investigators’ main finding of no survival advantage among the matched groups at 5 years is in line with most reports comparing patency between arterial and venous grafts, “requiring between 5- and 10-year follow-up to show a divergence,” Dr. Drinkwater said.

He pointed out that the patients who had second arterial grafts in the unmatched group were younger and healthier – the average age was 62 years, and 27% of them had previous heart attacks, compared with 66 years of age and a heart attack rate of 35.6% in the venous graft group – and that may explain the higher reintervention rate in the former group. Another factor may be the younger and healthier patients had longer cardiopulmonary bypass and aortic cross clamp times despite a greater percentage having undergone the off-pump technique.

“This counterintuitive information underscores an inherent weakness of this multicenter trial that is without surgical randomization into the two arterial groups, and with potentially varied surgical experience using nonstandardized technical and management protocols,” Dr. Drinkwater said. “This is in stark contrast to the previous and well accepted single high-volume-center reports of the benefits of using multiple arterial bypass grafts.”

Because the report points out the technical challenges of achieving complete revascularization with multiple arterial grafting at “the early” interval of up to 5 years, the authors may be inappropriately discouraging centers that do not currently offer multiarterial grafting from embracing it, Dr. Drinkwater concluded.

He had no disclosures to report.


 

FROM THE JOURNAL OF THORACIC AND CARDIOVASCULAR SURGERY

While single-center studies have supported the advantages of multiple arterial grafts over venous grafts in coronary artery bypass surgery, an analysis of patients in the international and multicenter SYNTAX trial has shown that, on propensity matching, rates of cardiac events and death are actually similar between the two groups.

These findings of the SYNTAX investigators, led by Dr. Catalina Parasca of Erasmus University in Rotterdam, the Netherlands, were published online in the Journal of Thoracic and Cardiovascular Surgery (doi:10.1016/j.jtcvs.2015.05.010).

The SYNTAX trial compared percutaneous coronary intervention (PCI) with coronary artery bypass grafting (CABG) in patients with left main or three-vessel coronary artery disease (Lancet. 2013;381[9867]:629-38).

In the latest report, the SYNTAX investigators found that patients in unmatched groups who received arterial grafts in addition to an arterial graft of the left anterior descending artery (LAD) had noticeably lower rates of death and a composite endpoint of death-stroke-MI than did those who received a second venous graft. However, when the researchers applied propensity matching, the outcomes between the two groups were similar.

Percentage arterial (red), venous (blue) grafts shown in relation to distal anastomoses; LAD, left anterior descending; Diag, diagonal; LCx, left circumflex; OM, obtuse marginal; PL, postero-lateral; RCA, right coronary; PDA, Posterior descending artery. Coutresy of JTCVS/American Association for Thoracic Surgery

Percentage arterial (red), venous (blue) grafts shown in relation to distal anastomoses; LAD, left anterior descending; Diag, diagonal; LCx, left circumflex; OM, obtuse marginal; PL, postero-lateral; RCA, right coronary; PDA, Posterior descending artery.

Because large randomized trials have yet to prove the superiority of multiarterial grafts, the adoption rate has been low, Dr. Parasca and colleagues said. “The objective of this study was to assess the effect of using a second arterial graft on 5-year outcomes in patients who underwent CABG in the SYNTAX trial and registry,” they said.

They looked at 1,322 SYNTAX trial patients who had CABG with 5-year follow-up. In unmatched groups, the safety endpoint of the death-stroke-MI composite was 13.3% in the multiarterial group vs. 18.7% in the vein graft group. Although the incidence of stroke, MI, and graft occlusion was similar between the unmatched groups, the second-graft arterial group had a higher revascularization rate at 5 years, 12.6% vs. 9.6%, mainly due to repeat PCI. The element of the composite where the two unmatched groups deviated was the all-cause death rate at 5 years: 8.9% in the second-graft arterial group and 13.1% in the venous group.

However, when the investigators applied propensity matching, the differences between the two groups were insignificant.

“The results of the present study must be seen in the light of a multicenter CABG cohort with complex coronary disease, where revascularization was performed according to surgeon’s personal experience and local practices,” Dr. Parasca and coauthors noted. “The result was a high heterogeneity of CABG techniques, which shows different understanding of the best ‘graft-target match’ across centers.”

While the SYNTAX analysis demonstrates the variation in patient selection and operator technique with regard to arterial revascularization typical of a multicenter study, “extended follow-up beyond 5 years is required to estimate its impact on long-term outcomes,” Dr. Parasca and colleagues said.

Boston Scientific supported the trial. Coauthor Keith Dawkins is employed by Boston Scientific and coauthor Ted Feldman has received consulting fees from the company. The other authors reported no disclosures.

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