SAN FRANCISCO, California — New results from three trials comparing off-pump and on-pump CABG have not been able to make a definitive case that off-pump is better for high-risk patients, despite that still being the belief of all the surgeons leading the studies.

The three trials were presented here today at the late-breaking clinical-trials session at the American College of Cardiology (ACC) 2013 Scientific Sessions. Two trials have also been published online today in the New England Journal of Medicine [1,2].

Two large-scale studies--first results from the German Off-Pump CABG in Elderly Trial (GOPCABE) and 12-month results from the CORONARY study--showed similar findings with nonsignificant differences between the two procedures at 30 days and 12 months. A third, much smaller, single-center Czech study--PRAGUE-6--did show a benefit of off-pump, but with only 200 patients, it is difficult to draw conclusions from these data.

Benefit Difficult to Prove

Dr Michael Mack

One of the discussants, Dr Michael Mack (Baylor Health Care System, Dallas, TX), said: "Despite all this experience with two very large studies, no clear benefit has been shown with off-pump." Noting that the main criticism of previous studies was that they included too many low-risk patients, making it difficult to show differences, he added: "These trials selected higher-risk patients, but still no major differences have been found."

Dr Anno Diegeler

GOPCABE presenter Dr Anno Diegeler (Herz-und Gefäßklinik Bad Neustadt, Germany) said he still believes true high-risk patients would benefit from off-pump surgery if the surgeon is highly experienced, but "it is difficult to prove in a randomized trial. I think a good service should include surgeons trained in both techniques, and each case should be decided on an individual basis."

Dr Andre Lamy

CORONARY lead investigator Dr Andre Lamy (McMaster University, Hamilton, ON) agreed with this stance. "We thought off-pump would be associated with lower morbidity/mortality and reduced transfusions. We haven't been able to show it yet, but results are going in the right direction. Maybe there will be a difference by five years, which is a prespecified end point in our study," he said.

He added: "Surgeons believe that low-risk patients do better on-pump and high-risk patients do better off-pump. That is what we are doing in our practice now."

At a press conference, ACC 2013 meeting cochair Dr Mark Davies (Methodist Cardiovascular Surgery Associates, Houston, TX) said the new results "probably tempered the enthusiasm about the benefits of off-pump surgery." He added: "In the right hands, with well-trained surgeons, off-pump does well, but on-pump is not dead."'

GOPCABE

The GOPCABE study included 2539 patients randomized to off-pump or on-pump surgery. Patients were high risk, with a mean age of 78.5 years and a EuroSCORE of 8 in both groups. During the course of the trial, 9% of patients crossed over from off-pump to on-pump, and 5% crossed over from on-pump to off-pump.

The primary end point--a composite of death, MI, stroke, repeat revascularization, and new renal-replacement therapy--was similar in the two groups, as were most of the individual components.

GOPCABE: 30-Day Results

End point Off-pump (%) On-pump (%) HR (95% CI) p
Primary composite 7.8 8.2 0.95 (0.71–1.28) 0.74
Death 2.6 2.9 0.92 (0.57–1.51) 0.75
MI 1.5 1.7 0.92 (0.51–1.66) 0.79
Stroke 2.2 2.7 0.83 (0.50–1.38) 0.47
Repeat revascularization 1.3 0.4 2.42 (1.03–5.72) 0.04
New renal replacement therapy 2.4 3.1 0.80 (0.49–1.29) 0.36

In a per-protocol analysis, results showed more trends toward benefits of off-pump, particularly in terms of MI and stroke, but these did not reach significance. Fewer off-pump patients received blood transfusions (56% vs 63%).

One-year results were not much different from the 30-day results, with the composite end point occurring in 13% of off-pump vs 14% of on-pump patients.

CORONARY

The 12-month results of the CORONARY trial (in 4752 patients), like the 30-day results reported at last years' ACC meeting, showed no difference in the primary end point, a composite of death, stroke, MI, and renal failure.

Lamy concluded that, in experienced hands, both procedures are reasonable options.

CORONARY: One-Year Results

End point Off-pump (%) On-pump (%) HR (95% CI)
Primary composite 12.2 13.3 0.91 (0.77–1.07)
Death 5.2 5.0 1.03 (0.80–1.32)
Nonfatal MI 6.8 7.5 0.90 (0.73–1.12)
Stroke 1.5 1.7 0.90 (0.57–1.41)
New renal failure 1.3 1.3 0.97 (0.59–1.60)

Neurocognitive Testing Difficulties

Dr Bernard Gersh

There was also no difference in quality of life or neurocognitive function between the two groups. However, only half the patients in the study actually came back for the neurocognitive tests, making this result difficult to interpret. Lamy noted: "Some centers were having difficulty doing these neurocognitive assessments, so we made them optional. These tests are not easy to do or to undergo, and the patients who came back for them were generally less sick."

Discussant Dr Bernard Gersh (Mayo Clinic, Rochester, MN) said he thought this was a big selection bias. "If there is an advantage to off-pump, it could well be in neurocognitive function. And the sicker patients are the ones who are more likely to show a deficit with on-pump surgery."

PRAGUE-6

Dr Jan Hlavicka

The third study, PRAGUE-6, was presented by Dr Jan Hlavicka (Charles University, Prague, Czech Republic). The study enrolled 206 high-risk patients with a EuroSCORE ≥6 randomized to off-pump or on-pump surgery. At 30 days, results showed a reduction in the primary end point of death, MI, stroke, or new renal failure requiring dialysis.

PRAGUE-6: 30-Day Results

End point Off-pump (%) On-pump (%) HR (95% CI)
Primary composite 9.2 20.6 0.41 (0.19–0.91)
Death 4.1 5.6 0.73 (0.21–2.58)
MI 4.1 12.1 0.32 (0.11–0.99)
Stroke 2.0 2.8 0.73 (0.12–4.35)
New renal failure 1.0 4.7 0.22 (0.03–1.85)

Hlavicka pointed out that there was also a reduction in transfusion or reexploration for bleeding/tamponade in the off-pump group.

Dr Neal Kleiman

Session chair Dr Neal Kleiman (Methodist Hospital Research Institute, Houston, TX) said part of message may be: "Short-term morbidity is less in very high-risk patients with off-pump, possibly because the procedure is shorter." Hlavicka agreed with this, saying: "The shorter the procedure, the better, especially for older, sicker patients. The length of the procedure is significantly shorter with off-pump than on-pump."

Gersh, however, took issue with the MI end point, which drove the reduction in the primary composite end point, as it was defined by rises in CK-MB and not new Q-wave MI. "I think you need to reanalyze the data with the more stringent definition of MI." But Kleiman pointed out that the other components of the composite also looked better.

Comments

3090D553-9492-4563-8681-AD288FA52ACE
Comments on Medscape are moderated and should be professional in tone and on topic. You must declare any conflicts of interest related to your comments and responses. Please see our Commenting Guide for further information. We reserve the right to remove posts at our sole discretion.
Post as:

processing....