Implantable defibrillators devices that detect and correct an abnormal heart rhythm are associated with a high risk of long-term complications, a new study suggests.
High rate of complications
"An implantable cardioverter-defibrillator is a highly effective treatment option to reduce the risk of sudden cardiac death," said lead researcher Dr Isuru Ranasinghe, a senior cardiologist at the University of Adelaide in South Australia.
"However, there is a substantial and persistent risk of device-related complications and re-operations in the years after implantation."
These complications include device malfunction, infection and inflammation, the study authors said.
Ranasinghe said the rate of complications is 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," he said.
But one cardiologist not involved with the study called the risk of complications "modest" and added that the benefits offered by the devices outweigh the risks.
ICDs are battery-powered devices placed in a "pocket" under the skin to keep track of a patient's heart rate, according to the American Heart Association. When an abnormal or chaotic heart beat occurs, the device is meant to shock the heart and restore a normal heart rhythm.
Simpler may be better
For the study, researchers analysed the performance of three types of implantable defibrillators – single-chamber, dual-chamber and cardiac resynchronization therapy devices (CRT-D). The investigators found the chances for trouble were greater with more complex devices, especially CRT-D devices.
Compared with simpler devices, CRT-D devices have a 38 percent higher rate of complications, and quadruple the risk for procedures such as battery replacement and upgrades, the researchers determined.
"This is important because choosing a simpler device at the start may help patients by reducing complications and delaying the need to replace the device," Ranasinghe said.
The ICD lifespan is typically up to seven years, depending on when the battery needs replacing, Ranasinghe said.
"More complex devices are more active, and their battery needs replacing earlier, compared with simpler devices," he explained.
According to background notes with the study, most ICDs used in the United States are dual-chamber or CRT-D. And two-thirds of patients never receive defibrillation but are exposed to device-related harms.
"There is considerable debate as to the added benefit of more complex devices compared with simpler, single-chamber ICDs," Ranasinghe said. "Where possible, using a simpler device may reduce the risk of ICD-related harm."
One expert believes the risk of complications is "modest", not significant enough to change current practice.
"Clinical trials have shown that implantable defibrillators prolong life, with benefits that outweigh potential risks," said Dr Gregg Fonarow, a professor of cardiology at the University of California, Los Angeles.
Higher risk for women and blacks
"Guidelines from the American College of Cardiology and American Heart Association recommend use of these devices along with medical therapies," Fonarow said.
These new findings "further reinforce current guideline recommendations for the use of these implanted devices in patients at risk for sudden death who are eligible and without contraindications," Fonarow said.
The report was published online in the Annals of Internal Medicine.
For the study, Ranasinghe and colleagues collected data on more than 114,000 men and women aged 65 and older who received an ICD between 2006 and 2010. The patients were followed for three years.
The researchers found that women and blacks had a somewhat higher risk of complications compared to men and whites. In addition, younger seniors – those 65 to 69 at implantation – had more complications than people 85 and older, Ranasinghe said.
Why women and blacks are more susceptible to complications isn't clear and requires further investigation, he said.
"Still, our findings can be used by physicians and patients to make an informed choice when weighing up the risks and benefits of an ICD," Ranasinghe added.