The increased risk of complication seen in the off-label patients may also result from the severity of the patient's cases more so than the ICD they were given, argued Dr. Peter McCullough, consultant cardiologist and chief academic and scientific officer at St. John Providence Health System, Providence Park Heart Institute, Warren, Mich.
"The observation that these so-called 'inappropriate' ICD patients had higher event rates suggests the doctors were identifying higher-risk patients using their judgment," he said. "These devices save lives. Studies like this call into question the appropriate use of databases in making judgments on the indications for cardiac procedures."
Duke's Al-Khatib agreed that it may be that the patients are sicker or it might just be an issue of timing. A large proportion of "inappropriate" ICD patients were those still recovering from a cardiac event or from a cardiac surgery, so performing the ICD implantation at that time might produce certain extra risks.
What's more, many cardiologists noted that given the lifesaving potential of the devices, the number of patients who should and do not receive an ICD may be more of an issue than those who receive it outside the realms of standard indications.
"[T]he first thing that strikes me is the irony that many of patients who do have an evidence-based, guideline recommended indication for an ICD do not have one, while some patients who fall outside of the guidelines are receiving ICDs," said Dr. William Abraham, director of the Division of Cardiovascular Medicine at Ohio State University.
Such is one of the limitations of using the National Cardiovascular Data Registry, said Dr. Cam Patterson, director of the University of North Carolina McAllister Heart Institute.
"Registry studies are notoriously difficult to draw conclusions from," he said. "The big challenge is that we get a snapshot of patients who received defibrillators, but we don't get to know anything in this study about patients who might need one but didn't have one implanted.
"We know that over half of individuals who should get an ICD implanted based on guidelines actually don't receive one, for a variety of reasons. This is a far bigger problem."
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