Heart defibrillator replacement can be high-risk surgery

Surgery to replace potentially defective heart defibrillators carries an unexpectedly high rate of serious complications, including death, according to a study published today.

The research in the Journal of the American Medical Association showed that one in 50 patients needed to have their replacement device removed because of severe post-operative infections.

Andrew D. Krahn of the University of Western Ontario, one of the authors of the study, said the overall complication rate was three to five times higher than had been expected.

“We were absolutely surprised by these numbers,” he said.

Two other studies in the journal tracked the annual malfunction rate of defibrillators, which started rising in the late 1990s as devices became more complex but began falling in 2002 and is now less than 1 percent.

Taken together, the three studies paint the fullest picture yet of the risks to patients of removing or retaining a defibrillator recalled by its manufacturer.

The reports come amid controversy about defibrillators, potentially lifesaving devices used to control heartbeats or jolt those in cardiac arrest.

Medtronic Inc. and Guidant Corp. last year issued warnings about flaws in their defibrillators. Guidant also faces a Justice Department investigation related to its safety alerts. The company told the Food and Drug Administration about electrical problems with its Ventak Prizm 2 DR device but did not provide that information to patients and doctors.

An estimated 135,000 patients receive a defibrillator each year to prevent a sudden heart attack. The devices differ from pacemakers, older, less complex devices that use tiny currents of electricity to regulate slow heartbeats.

Krahn said doctors had long believed the complication rate for defibrillator surgery ranged from 1 percent to 2 percent, about the same as for routine operations.

But his study of 533 patients at 17 Canadian medical centers who elected to have their defibrillators replaced after a safety recall found that 43 patients, or 8.1 percent of the total, suffered infections and other complications within three months of their surgery. Of those, 31 patients, or 5.8 percent, had severe complications, and two died. Ten patients with bad infections needed to have their replacement device removed.

His study was the first to examine the rate of complications associated with replacing defibrillators, a procedure typically performed every five to seven years because the batteries wear out.

Krahn couldn’t explain why the complication rate was so high. The study suggests patients and their doctors should carefully weigh the risks of complications before removing their defibrillators after a safety alert, he said.