Over three decades, 1.6% of the patients who underwent coronary artery bypass graft surgery (CABG) at the Cleveland Clinic had a stroke during or shortly after the procedure.
The stroke rate declined slowly from a peak of 2.6% in 1988, although patients coming to have the operation were arriving in poorer condition.
"The patients are at significantly higher risk than they used to be five or 10 years ago," said Dr Farzan Filsoufi, a heart surgeon at The Mount Sinai Medical Centre in New York City, who was not involved in the new work.
"Despite the increase in risk factors, the incidence of strokes has decreased in most studies."
Some doctors have used the stroke threat to push for a less invasive procedure called percutaneous coronary intervention, or PCI, Dr Filsoufi said. But with the lower stroke rates seen at some hospitals today, stroke concern is no longer a good argument to choose PCI over surgery, he added.
"CABG is a very safe operation today," he said.
The current study
For the current study, published online January 25th in the Journal of the American Medical Association, the Cleveland Clinic researchers looked at data from more than 45,000 patients who had CABG surgery between 1982 and 2009.
Of the 705 people who suffered a stroke, 40% had them intra-operatively. Ten years later, 68% of those who didn't have a stroke were still alive, compared to only 37% of those who did.
Certain types of surgery were tied to a lower stroke risk. Patients whose hearts were left beating during the procedure had the lowest risk of stroke - as low as 0.14% during the surgery - while those on bypass with stopped hearts were at higher risk.
The stroke rate climbed with age and the degree of heart disease.
"If you tailor the operation to the patient, you can bring the risk down to that seen in PCI," said Dr Joseph Sabik, head of the heart surgery department at the Cleveland Clinic.
Reason for the decline
He said the reason for the decline in stroke rates over time was probably related to this approach.
"It has to do with picking the right procedure for the patient," he said, "and then there are also the things you do before and after the surgery, such as giving better medicines."
Dr Sabik added that while PCI might be right for some patients, surgery is more effective at preventing later deaths from heart attacks and the need for new interventions.
For patients, the take-home message of the study is not that one intervention is necessarily better than another, he said, but to make sure they get the one that suits their needs best.
"If you need to have heart surgery, ask your surgeon how he's going to do it, and why he is going to do it that way," Dr Sabik urged. "If he says, 'That's just the way I do it,' that's not a good answer."(Reuters Health/ January 2011)