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Report Shows Implanted Cardioveter-defibrillators Carries High Risk


NEW YORK (Reuters Health) - Implanted cardioverter-defibrillators (ICDs) carry a high risk of long-term complications, especially for younger patients, women, and blacks, researchers report.

Early implantation-related risks such as device malfunction are well known, but longer-term risks -- especially beyond the first year after implantation -- are poorly defined, Dr. Isuru Ranasinghe of Queen Elizabeth Hospital in South Australia and colleagues observed in an article online May 2 in Annals of

Internal Medicine.

"Knowing the long-term risks is important for patients to make an informed choice, because (implantation) is a lifelong treatment," Dr. Ranasinghe told Reuters Health by email. "Moreover, more than two-thirds of patients who receive an ICD for prevention of future events never require treatment from the ICD, although they continue to be at risk for device-related harms."

To investigate, the researchers analyzed data from the American College of Cardiology Foundation's National Cardiovascular Data Registry ICD Registry and Medicare claims to assess the long-term nonfatal risks for ICD-related complications among 114,484 patients at 1,437 U.S. centers with first-time implantations.

Implanted devices included single-chamber ICDs (19.8% of patients); dual-chamber ICDs (41.3%), and cardiac resynchronization therapy with a defibrillator (CRT-D; 38.9%).

During a median follow-up of 2.7 years, 40,072 patients died, representing 12.6 deaths per 100 patient years of followup. After accounting for the deaths, "there were 6.1 ICD-related complications per 100 patient years where the patient required an acute hospitalization or a reoperation," Dr. Ranasinghe said.

"In addition, there were 3.9 device reoperations per 100 patient years for reasons other than complications. Typically performed to replace the ICD battery, these reoperations are somewhat expected with time. Nevertheless, these surgical procedures are important for patients, as they carry a risk of patient harm," he observed.

Those more likely to experience long-term complications were women (16% higher risk), blacks (14% higher risk), and patients ages 65-69 at implantation (55% higher risk compared with those 85 and older) -- findings that require further investigation, according to Dr. Ranasinghe.

"Patients were 38% more likely to experience a complication if they had the more complex CRT-D compared with a simpler (single-chamber) device. A patient with a CRT-D device was also four times more likely to require a reoperation for reasons other than complications compared with a single-chamber ICD during the study period," he said.

Dr Ranasinghe added, "The rate of complications is substantial and higher than previously reported. The continued occurrence of complications long after the initial implantation indicates the need for vigilance and ongoing surveillance of ICD-related complications."

"There is considerable debate as to the added benefit of more complex devices compared with simpler single-chamber ICDs. Where possible, using a simpler device may reduce the risk of ICD-related harm," he said.

Dr. Paul J. Hauptman of Saint Louis University School of Medicine in Missouri, told Reuters Health by email, "The study adds to a rich literature that highlights the need for clinicians and patients to carefully consider the potential risks and benefits of implantable defibrillators and CRT devices."

"Although (this was) not a primary focus of the paper, I was struck by the 35% mortality at a median of 2.7 years (in addition to a significant ICD-related complication rate)," said Dr. Hauptman, who has done work in this area. "By linking registry and Medicare data, the authors succeed in providing meaningful insight into what happens to real patients in the real world. We would be abrogating our role as physicians if we ignore analyses like this one."

The study was funded by the American College of Cardiology Foundation's National Cardiovascular Data Registry and other organizations. Five coauthors reported disclosures.

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