A study published in the January 1 issue of the New England Journal of Medicine, describing worse outcomes in patients who have off-pump coronary artery bypass surgery compared to patients who have standard bypass surgery, have both doctors and patients in a tizzy.
"Off-pump" bypass surgery is a relatively new procedure using recently available technology to allow surgeons to bypass coronary arteries without stopping the beating heart and using a relatively small incision(indeed, off-pump surgery is sometimes referred to as "beating-heart" surgery).
In contrast, in conventional on-pump surgery the heart is stopped for a period of time so the doctor can do the grafting, and during this time the patient's blood is artificially circulated to the rest of the body via a specialized pump (called the heart-lung bypass machine). This bypass pump is thought to be at least partially responsible for some of the complications seen after bypass surgery. (For instance, click here to read about "pump head." ) For this reason, off-pump surgery has been rapidly gaining in popularity.
Prior studies have shown that off-pump surgery can be performed without producing new complications, but until now no randomized trials have been conducted to the compare long-term effectiveness of off-pump vs. on-pump bypass surgery.
In the study published this week, which was conducted at the Royal Brompton Hospital in London, UK, 102 patients were randomly assigned to receive either off-pump or on-pump bypass surgery. Patients then had repeat cardiac catheterization after 3 months.
The investigators found that in the off-pump patients, 12% of the grafts had occluded, whereas on the on-pump patients only 2% of grafts were occluded. This 6-fold difference in the 3-month success of the bypass operation was highly significant statistically. This difference did not appear to be related to either the vessel bypassed, or they type of bypass used (i.e., a vein graft or an artery graft.)
These results left both the investigators themselves and the doctors who wrote the accompanying editorial (all of whom are cardiac surgeons) in a state of polite disagreement over what these rather striking results mean. The investigators speculate that the differences are due to the relative immaturity of the off-pump procedure and to unanswered questions about which patients are most suitable to this approach. On the other hand, the editoralists suggest (as politely as possible) that the results may be related to the skill of the surgeons (the implication being, one presumes, that you shouldn't have off-pump surgery in their hospital, but it's quite safe to have it in mine.) Both groups agree that more study is called for.
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