DENVER – Failure rates for the St. Jude Medical Riata ST Optim and Durata implantable cardioverter-defibrillator leads were reassuringly low in an independent analysis of three large prospective registries.
The study was undertaken at company expense because St. Jude Medical’s earlier-generation, silicone-wrapped Riata and Riata ST ICD leads were so failure-prone, that they were recalled several years ago. Their replacements – the subject of the new study – are insulated with Optim, a proprietary silicone/polyurethane copolymer with exceptional mechanical strength, flexibility, and abrasion resistance, according to Dr. John A. Cairns, who presented the registry study analysis at the annual meeting of the Heart Rhythm Society.
Dr. John A. Cairns
The prospective, St. Jude Medical–sponsored OPTIMUM, SJ4, and SCORE registries totaled 11,005 Durata and Riata ST Optim leads implanted in 10,820 patients. Median follow-up to date in the study, conducted independently under the direction of the Population Health Research Institute at McMaster University in Hamilton, Ont., is 3.0 years. Sixty-four percent of the leads remain under active follow-up, according to Dr. Cairns, who chairs the study steering committee and is professor of medicine at the University of British Columbia, Vancouver, as well as president-elect of the Canadian Academy of Health Sciences.
Participation in the registries entails patient follow-up every 6 months, with device interrogation encouraged. Participating physicians are supposed to return inactivated leads to St. Jude Medical for detailed analysis.
To date, the all-cause mechanical failure rate in the combined analysis is 0.35%, with a 0.22% conductor fracture rate, an insulation abrasion rate of 0.07%, and no cases of externalized conductors.
A life-table analysis was used to derive the 99.4% estimated 5-year rate of freedom from all-cause mechanical failure. The 5-year freedom from conductor fracture was 99.6%, with a 99.9% freedom from insulation abrasion and 100% freedom from externalized conductors.
Dr. John D. Day
Dr. Cairns said the company registries have been rigorously conducted, with central reporting and formal definitions of adverse events. Those strengths, coupled with the independent outside analysis, make the resultant findings more "in the realm of clinical trials rather than so much of the anecdotal information that’s out there," he added.
Session cochair John D. Day said in an interview that he considered the data "great news for patients with those leads" and was "cautiously optimistic" regarding the long-term performance of the ICD leads. He noted, however, that as of this analysis only 551 leads had actually reached the 5-year follow-up point. Many thousands more will do so in the next several years, at which point definitive conclusions can be drawn, according to Dr. Day, director of heart rhythm specialists at Intermountain Healthcare, Salt Lake City.
Dr. Cairns reported serving as a consultant to St. Jude Medical.