STOCKHOLM — The batteries of implantable cardioverter-defibrillators are not keeping up with patient life span, suggesting that a lot of patients will need follow-up surgery to get their batteries replaced.
“Unless the service life of pulse generators [implantable cardioverter-defibrillators] improves substantially, patients will undergo more frequent replacement protocols, and ICD costs will continue to increase at an alarming rate,” Robert G. Hauser, M.D., said in a poster presented at the annual congress of the European Society of Cardiology.
“As indications expand, longer-[life] ICDs will be needed if this treatment is to be cost beneficial,” said Dr. Hauser, a cardiologist with the Minneapolis Heart Institute Foundation.
He reviewed the outcomes of all patients who received ICDs at the institute during 1994–2005. The group included 813 patients who received single-chamber defibrillators, 616 who got dual-chamber units, and 405 with cardiac resynchronization devices.
The rate of failure due to battery depletion began to rise 3.5 years after the single-chamber devices were placed, and after 7 years about 95% had failed. Dead batteries began to pile up after 4 years for the dual-chamber implants, and after about 5 years approximately 80% had failed. The cardiac resynchronization devices burned out even faster, starting to fail after 2 years, and after 3 years about 30% had stopped working.
Patients survived much better than their batteries. Among those who had a left ventricular ejection fraction of at least 40% at the time of their implant, 90% lived for 5 years and 65% lived for 10. Patients with ejection fractions of less than 40% had a 5-year survival rate of approximately 70%, and about 40% lived for 10 years.