Studies Fail to Tame Controversy Over Off- vs. On-Pump CABG

SAN FRANCISCO, CAWhile 2 studies comparing off-pump vs. on-pump coronary artery bypass graft (CABG) surgery showed few differences in outcomes, a third study demonstrated less adverse events with the off-pump approach. All 3 studies were presented March 11, 2013, at the American College of Cardiology/i2 Scientific Session.

In the international, multicenter CORONARY trial, André Lamy, MD, of the Population Health Research Institute (Hamilton, Canada), and colleagues randomized 4,752 CAD patients already scheduled to undergo bypass to an off- (n = 2,375) or on-pump (n = 2,377) procedure from November 2006 through October 2011.

The 1-year results were simultaneously published online in the New England Journal of Medicine.

Patients treated with off-pump and on-pump CABG had similar rates of the primary composite outcome (death, nonfatal MI, nonfatal stroke, or nonfatal new renal failure requiring dialysis; 12.1% vs. 13.3%; HR 0.91; 95% CI 0.77-1.07; P = 0.24). Results remained consistent when the first 30 days were eliminated from the analysis (HR 0.79; 95% CI 0.55-1.13; P = 0.19).

Rates of recurrent angina and need for repeat revascularization were similar between the 2 arms, and in a separate analysis of 2,850 patients, there were no differences in quality of life or neurocognitive function.

Enthusiasm Waning for Off-Pump?

Operators were required to have 2 years’ experience as a staff cardiac surgeon and to perform 100 or more cases of 1 or both techniques.

“In experienced hands, both procedures are reasonable options based on mid-term results,” Dr. Lamy said, adding that patients will be followed out to 5 years.

However, panel co-chair Jeffrey B. Rich, MD, of Sentara Norfolk General Hospital (Norfolk, VA), expressed concern as to the relative benefits of off-pump procedures. “As an early advocate of off-pump surgery, it’s getting harder and harder to maintain enthusiasm for it,” he said. “One of the early reasons for doing off-pump surgery was to perhaps have better neurocognitive outcomes and avoid ‘pump-head,’ and you’ve been unable to demonstrate any difference in quality of life or neurocognitive outcomes.”

But perhaps the most challenging question came from panelist Christopher P. Cannon, MD, of Harvard Medical School (Boston, MA). “Why would you want to do off-pump if it doesn’t seem to help and it’s harder to do?” he asked.

“The results around the world are different,” Dr. Lamy explained, adding that patients with lower EuroScores tend to do better with on-pump procedures while off-pump leads to benefit in those with higher EuroScores. “In India and China, you have a higher proportion of patients with lower EuroScores.”

The take-home message, however, is that “surgeons should know both techniques and be able to adjust their surgical practice according to their patients,” Dr. Lamy concluded.

GOPCABE: No Difference in Elderly

Moving on to elderly cohorts, the German Off-Pump Coronary Artery Bypass Grafting in Elderly Patients (GOPCABE) study led by Anno Diegeler, MD, PhD, of Cardiovascular Clinic Bad Neustadt (Bad Neustadt, Germany), randomized 2,539 patients age 75 years or older to on- (n = 1,268) or off-pump (n = 1,271) CABG.

GOPCABE also was published simultaneously online in the New England Journal of Medicine.

At 30 days, the primary composite endpoint of death, stroke, MI, or new renal-replacement therapy was similar between both study arms, as were the individual component endpoints with the exception of repeat revascularization, which was increased with off-pump CABG (table 1).

Table 1. Thirty-day Outcomes (GOPCABE)

 

 

Off-Pump CABG
(n = 1,271)

On-Pump CABG
(n = 1,268)

P Value

Primary Composite

7.8%

8.2%

0.74

Death

2.6%

2.8%

0.75

MI

1.5%

1.7%

0.79

Stroke

2.2%

2.7%

0.47

Repeat Revascularization

1.3%

0.4%

0.04

New Renal-Replacement Therapy

2.4%

3.1%

0.36


The same was true at 1 year, while the difference in repeat revascularization was reduced to a trend (table 2).

Table 2. One-Year Outcomes (GOPCABE)

 

 

Off-Pump CABG
(n = 1,271)

On-Pump CABG
(n = 1,268)

P Value

Primary Composite

13.1%

14.0%

0.48

Death

7.0%

8.0%

0.38

MI

2.1%

2.4%

0.70

Stroke

3.5%

4.4%

0.26

Repeat Revascularization

3.1%

2.0%

0.11

New Renal-Replacement Therapy

2.9%

3.5%

0.37

 

The primary analysis was based on a modified intention-to-treat principle. In a subsequent per-protocol analysis excluding 177 patients who crossed over from their assigned treatment, the findings remained consistent, showing no benefit with off-pump vs. on-pump CABG in elderly patients.

Proof Hard to Come By

Panel member Michael J. Mack, MD, of Baylor Health Care System (Dallas, TX), commented to Dr. Diegeler that “we’ve had 1 recent study, ROOBY, that showed patients may be hurt by off-pump surgery, and now 2 large studies, CORONARY and your own that show although patients don’t fare worse, there’s not a clear benefit to it, so what’s the take-away message? Should we continue to do it? Is there any group at all that benefits from it?”

Dr. Diegeler responded that “for those groups that are very experienced in off-pump, for some high-risk individual patients, you get benefit, but it’s hard to get proof in a randomized study.

Along the same lines, panel co-chair Neal S. Kleiman, MD, of Methodist DeBakey Heart and Vascular Center (Houston, TX), asked Dr. Diegeler, “Do you think there’s room to progress, or have we reached a plateau in terms of the [off-pump] technique?”

Dr. Diegeler affirmed that “a good coronary program should include off pump techniques. I’m very sure of it.”

PRAGUE-6: Different from the Rest

Providing a bit more encouragement to proponents of the off-pump strategy, Jan Hlavicka, MD, of Charles University (Prague, Czech Republic), presented 30-day outcomes for 206 patients enrolled in the single-center PRAGUE-6 trial. All patients in this study had a EuroScore of 6 or greater (mean, 7.6) and were randomized to on- (n = 108) or off-pump (n = 98) CABG.

For the primary combined 30-day endpoint of death, MI, stroke and new renal failure requiring hemodialysis, patients in the off-pump group had significantly better outcomes compared with the on-pump group driven primarily by reductions in acute MI (table 3).

Table 3. Thirty-day Outcomes (PRAGUE-6)

 

 

On-Pump
(n = 108)

Off-Pump
(n = 98)

P Value

Primary Endpoint

20.6%

9.2%

0.028

Death

5.6%

4.1%

0.623

Acute MI

12.1%

4.1%

0.048

Stroke

2.8%

2.0%

0.726

Hemodialysis

4.7%

1.0%

0.163

 
In addition, a significantly higher percentage of on-pump patients required a blood transfusion compared with off-pump patients (80.2% vs. 64.9%; P = 0.017). There was no significant difference in the need for re-exploration for bleeding or tamponade (8.5% vs. 3.2%; P = 0.38).

“The PRAGUE-6 study has shown that off-pump surgery in high-risk patients is associated with a lower incidence of serious complications,” Dr. Hlavicka said. “Off-pump surgery is a safer way of direct revascularization in these patients.”

Dr. Cannon commented that the PRAGUE-6 data are a good example of “what can work if done well.” However, Dr. Mack pointed out that it took 5 years to enroll 200 patients in the study, indicating the rigid patient selection process, and asked Dr. Hlavicka what type of patients he felt should be considered for off-pump surgery.

“I would say all patients with high operative risk with EuroScore more than 6,” Dr. Hlavicka said, adding that his center has begun following this protocol as a result of the PRAGUE-6 experience.

 

 


 

Sources:1. Lamy A, Devereaux PJ, Dorairaj P, et al. Effects of off-pump and on-pump coronary-artery bypass grafting at 1 year. N Engl J Med. 2013;Epub ahead of print.

 

2. Diegeler A, Börgermann J, Kappert U, et al. Off-pump versus on-pump coronary-artery bypass grafting in elderly patients. Diegeler A, Börgermann J, Kappert U, et al. Off-pump versus on-pump coronary-artery bypass grafting in elderly patients. N Engl J Med. 2013;Epub ahead of print.

3. Hlavicka J. PRAGUE-6 trial: Off-pump versus on-pump coronary artery bypass graft surgery in patients with EuroSCORE ≥6. Presented at: American College of Cardiology Annual Scientific Session; March 11, 2013; San Francisco, CA.

 

 

 

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Disclosures
  • The CORONARY trial was sponsored by the Canadian Institutes of Health Research.
  • GOPCABE was sponsored by the German Society of Thoracic and Cardiovascular Surgery and supported by an unrestricted grant from Maquet.
  • PRAGUE-6 was supported by an unrestricted grant from Edwards, Jena Valve, Medtronic, Sorin, St. Jude and Symetis.
  • Drs. Diegeler, Lamy and Hlavicka report no relevant conflicts of interest.

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