The guidelines concerning when such a device is appropriate may be overruled in certain circumstances, said lead author on the study and researcher for the Duke Clinical Research Institute, Dr. Sana Al-Khatib. But the recommendations are based on multi-centered randomized clinical trials showing that the device does not help under certain conditions.
"The physician has to use his or her judgment -- even the guideline documents allow for these deviations, [but] I would not expect this to account for close to 23 percent of all ICD implants," he said. "Clearly there is room for improvement."
Dr. Richard Besser, chief health and medical editor for ABC News, agreed, noting that considering that the off-label use of ICDs varied from less than 5 percent of all implantations to 55 percent, depending on the center, "improvement needs to focus on interventions at the doctor and hospital level."
How closely doctors should stay to the recommended guidelines and the extent to which the "off-label" ICD usages should be minimized was a matter of debate among cardiac experts.
Given the lack of evidence supporting the utility of these devices outside the guidelines, the off-label use of ICDs is "completely inappropriate," said Dr. Jonathan Steinberg, chief of the Division of Cardiology at St. Luke's-Roosevelt Hospital in New York City and director of Electrophysiology at The Valley Hospital in Ridgewood, N.J. Removing, or explanting the device, is often dangerous, he added, so patients might end up stuck with an unnecessary device, which is a "big issue when it comes time for device replacement and whether a new generator is warranted."
The need for strict adherence to the existing guidelines was less clear to other cardiologists, however, especially given the relatively small difference in risk of complication found by the study. About 3 percent of those outside the recommendations experienced post-procedure complications compared, with 2.41 percent for those within.
"Guidelines are simply recommendations made by a committee of experts, and the guidelines are often out-of-date with relevant clinical practice by the time they make it through the societies and are approved, often a 2-year process," said Dr. Arthur Moss, professor of cardiology at the University of Rochester Medical Center.
"There are always exceptions to guidelines ? and the attending physician-cardiologist is at liberty to make a relevant clinical decision based on the circumstances and risks presented by the patient."
Dr. Paul Friedman, professor of medicine and cardiovascular diseases at the Mayo Clinic in Rochester, Minn., said, "Guidelines combine medical evidence and expert opinion to inform best practices. However, guidelines are just that: guidelines," adding that patients should seek guidance on whether they need one from a physician with training and experience in defibrillator use.
By drawing from national registry data, the study provides only a snapshot into the patients receiving ICDs, some cardiologists warned, and so the study results cannot provide the full picture for why so many patients might be getting ICDs outside the recommended guidelines or why the patients might experience more complications.