Long-Term Cognition Better With OPCAB

ORLANDO — Patients treated with off-pump coronary artery bypass graft surgery had significantly better long-term neurocognitive function, compared with those who got percutaneous coronary intervention, in the first-ever randomized head-to-head comparison of the revascularization methods focusing on cognitive outcome.

At 7.5 years' follow-up in the Dutch multicenter Octopus Study, overall scores on a standardized neurocognitive test battery were significantly better in the off-pump coronary artery bypass (OPCAB) group, Dr. Jakub J. Regieli reported at the annual scientific sessions of the American Heart Association.

The OPCAB group scored significantly higher on four of the seven cognitive domains measured: visual memory, motor capacity, divided attention, and learning. Scores on the other three domains—reaction time, decision making, and working memory—also consistently favored the OPCAB patients, although in those instances the advantage fell short of statistical significance, according to Dr. Regieli, a cardiology fellow at the University of Utrecht (the Netherlands).

But discussant Robert C. Robbins was not buying Octopus. “I really have to question whether PCI would give worse neurocognitive function. I can tell you as a surgeon that if I had the choice of having a stent versus CABG, I'd take a stent every time—and I think I'd be smarter in the end,” said Dr. Robbins, professor and chairman of the department of cardiothoracic surgery at Stanford (Calif.) University.

There are several sound reasons for a patient to opt for OPCAB rather than PCI—a lower repeat revascularization rate, vessels unsuitable for stenting—but an expectation of better cognition outcome isn't one of them, Dr. Robbins said.

The Octopus population comprised 280 low-risk patients with preserved left ventricular function, single-vessel disease, and a mean age of 60 years.

The composite cardiac end point, which comprised death, stroke, or MI, occurred in 17.4% of the PCI group over the course of 7.5 years and was not significantly different, at 19.2%, in the OPCAB group. The mortality rate was 8.7% with PCI and 13.4% with OPCAB, a nonsignificant difference. But the 21.7% repeat revascularization rate in the PCI group was significantly higher than the 11.3% rate with OPCAB.

Manipulation of the aorta occurred in 100% of PCI patients but in only 15% of those who received OPCAB. That difference plays a key role in the Octopus investigators' interpretation of the cognitive outcome differences.

“It's known from imaging data that microemboli do occur during PCI. We would hypothesize that subclinical cerebral injury during repeated cardiac catheterization in the PCI-treated patients may have led to worse cognitive performance in that group,” Dr. Regieli explained.

Dr. Regieli added a caveat: PCI in Octopus was performed in the bare metal stent era. Contemporary PCI with drug-eluting stents has a lower repeat revascularization rate, and that might well spell better neurocognitive performance.

None of the cardiac findings is really surprising, in Dr. Robbins' view. The neurocognitive results are a different matter. He noted that 25% of patients in the PCI group did not undergo neurocognitive testing, compared with 13% in the OPCAB group—a difference that could have influenced the results. Also, no baseline neurocognitive testing was done prior to revascularization.

When Octopus was being planned over 8 years ago, there was widespread high hope that OPCAB was the answer to the neurocognitive impairment that often follows on-pump CABG, but that hope has not been fulfilled.

Now most heart surgeons consider the recently published Veterans Affairs Randomized On/Off Bypass (ROOBY) study the definitive statement, according to Dr. Robbins.

ROOBY randomized 2,203 patients scheduled for CABG to OPCAB or on-pump surgery. No significant differences between the techniques were found in neurocognitive outcomes (N. Engl. J. Med. 2009;361:1827–37).

Dr. Robbins said the hypothesis that manipulation of the aorta increases the likelihood that atheromatous microemboli will get knocked loose and injure the brain is intriguing. But “the 60-year-olds that I operate on don't have a lot of atheroma in the aorta,” he observed.

The Octopus Study was funded by the Netherlands National Health Insurance Council. Dr. Regieli and Dr. Nathoe reported having no conflicts of interest.