BOSTON – The problem-plagued St. Jude Riata leads for implantable cardioverter defibrillators, pulled from the U.S. market in 2010, continue to pose problems for the tens of thousands of patients who still have them as clinicians follow these patients out to periods approaching 10 years.
But the risks of lead extraction continue make prophylactic lead removal a poor option for most patients, leaving the alternative of continuing to closely monitor patients for episodes of electrical lead failure, Dr. Ratika Parkash said at the annual scientific sessions of the Heart Rhythm Society.
“Isolated, prophylactic lead revision or extraction is not warranted,” said Dr. Parkash, a cardiac electrophysiologist at Dalhousie University in Halifax, Canada. “We need to take into account a patient’s comorbidities compared with the possibility of cable externalization,” when the conducting cable of the lead moves outside its insulating sheath, one of the main problems with the St. Jude Riata leads, she explained. “I think we need to individualize what we do” based on each patient’s specific situation, but perhaps collecting more data during another 2 years follow-up might shed more light on this issue, she said. Dr. Parkash and her associates followed Riata-lead recipients for an average of 7.5 years to produce the current report.
Although no U.S. patient has received a Riata lead for nearly 5 years, the Food and Drug Administration estimated that at the time St. Jude stopped selling this lead in late 2010 more than 227,000 Riata leads had gone into patients worldwide, including about 79,000 U.S. patients. Last February, St. Jude announced that it had settled 950 lawsuits or claims from U.S. patients who had received Riata leads.
The CREDO (Canadian Registry of Cardiac Implantable Electronic Device Outcomes) prospective registry review reported by Dr. Parkash included data from 2,707 patients who received Riata leads at any of 15 Canadian centers, representing 60% of the 4,538 Canadian residents who had received on of these leads. The patients averaged 63 years of age, 19% were women, 70% had received an 8 French lead and 30% had received a 7F lead, and follow-up data were available for an average of 7.5 years from the time patients received the leads to attach their implantable cardioverter defibrillator (ICD) to their heart.
During follow-up, 378 of the 2,707 patients (14%) required revision of their leads, a rate well above the rates seen collectively for all ICD lead models in data collected in both randomized trials and in the U.S. national registry of ICD implantations maintained by the National Cardiovascular Data Registry (OpenHeart 2015;2: [doi:10.1136/openhrt-2014-000198]). The rate of lead revisions seen with the Riata lead, 14% during 7.5 years follow-up, puts it in the ballpark of the 17% lead-failure rate with 5 year follow-up seen in Canadian patients who received a Sprint Fidelis lead that was marketed by Medtronic.(Circulation 2012:1217-25)
Triggering the 378 Riata revisions were electrical abnormalities, in 42%, lead dislodgement in 18%, cable externalization in 12%, infection in 12%, and several other types of events causing the other revisions.
The rate of electrical failures remained steady throughout follow-up, averaging about 0.8%/ year for both the 8F leads, which the researchers could follow for up to 10 years, and for the 7F leads, which they followed out to as long as 8 years. Cable externalizations occurred in 7% of the 8F leads and in 5% of the 7F leads, a difference that was not statistically significant. Fewer than half the patients, 1,187 (44%) underwent radiographic assessment of cable externalization. About 90% of all the detected cable externalizations in both the 7F and 8F leads did not produce electrical failure.
A multivariate analysis identified two factors independently linked with lead failure: patient age and left ventricular ejection fraction. Every 10 years of additional patient age linked with a 16% reduced rate of lead failure. And every 10% in additional ejection fraction linked with a 26% increased rate of lead failure.
The Canadian experience also documented the risk of undergoing lead revision, which happened for 253 patients and which led to 16 major complications, a 6% rate. Fifteen of the 16 major complications occurred without lead extraction taking place. Also, the major complications occurred at roughly similar rates in patients with 7F or 8F leads.
Dr. Parkash also highlighted that cable externalization often occurs late after implantation, and so additional cases are still possible. “We may just be seeing the cusp of lead failure” in the data collected so far, she suggested.