Pacing Defibrillators May Carry More Risks: StudyDec 19, 2002 | CBC News Online
Sophisticated defibrillators may knock the heart out of rhythm, increasing the risk of hospitalization and death, according to a new study.
The costly models include a pacemaker that helps maintain a normal heart rhythm by delivering electrical impulses to both the heart's upper and lower chambers.
The dual-chamber implantable defibrillators are designed to continuously regulate a patient's heartbeat. This year, doctors worldwide implanted an estimated 80,000 defibrillators, and three-quarters of the devices had dual chambers.
But cardiologist Bruce Wilkoff of the Cleveland Clinic said that's far too many. He said only those patients whose heartbeats are dangerously slow need the newer defibrillators, and that's only about five per cent of patients.
Of the 506 defibrillator patients in the study, half had the new, dual-chamber defibrillators. The others had a backup pacemaker that stimulates only the lower heart chambers.
One year later, 26.7 per cent of the dual-chamber patients died or were hospitalized with heart failure. That compares with 16.1 per cent of patients with the simpler units.
Wilkoff said the dual-chamber devices might be riskier because continuously stimulating the right ventricle, the heart's lower chamber, may throw off the synchronization on the left side.
St. Jude Medical Corp. made the devices used in the study and paid for the research.
Michael Coyle of St. Jude Medical said the results show how pacemaker functions need to be programmed to minimize effects in those who don't need the extra help.
A spokesperson for Medtronic Inc., another company that makes defibrillators and pacemakers, said the study was flawed because none of the study's participants needed the sophisticated pacemaker.