Riata ICD Lead Failures
Riata ICD Lead Failures
Abstract & Commentary
By John P. DiMarco, MD, PhD Professor of Medicine, Division of Cardiology, University of Virginia, Charlottesville
Source: Hauser RG, et al. Deaths caused by the failure of riata and riata ST implantable cardioverter-defibrillator leads. Heart Rhythm 2012; Mar 23. [Epub ahead of print.]
The Riata and Riata ST ICD leads manufactured by St. Jude Medical have recently come under increased scrutiny because of the observation that the conductor cables could extrude from the outer insulation. To investigate the clinical significance of this finding, Hauser and colleagues queried the FDA Manufacturers And User facility Device Experience (MAUDE) database to examine reports of deaths that may have been caused by Riata and Riata ST lead failure. The MAUDE database is a voluntary reporting system maintained by the FDA. The majority of reports are filed by manufacturers who are required by law to report device-related adverse events. They compared the incidence of lead-related reported deaths to those for another ICD lead, the Medtronic Quattro Secure Model 6947. A lead-related death was defined as a sudden or unexpected death accompanied by evidence of a lead failure. An indeterminant death was one that was either nonsudden, the circumstances were unclear, or evidence of a lead defect was not provided. Deaths were thought to be not lead related if the death was nonsudden, expected for reasons related to the patient's health, and/or there was no evidence of lead failure. Lead malfunctions, high-voltage conductor short circuits, externalized conductor wires, inside-out abrasion, and can abrasions were also quantitated.
The authors' search of the MAUDE database using the terms "Riata death," and "Quattro Secure death" returned 133 deaths. There were 54 Riata and 17 Riata ST deaths in the MAUDE database. Of these, 18 (33%) Riata deaths and four (24%) Riata ST deaths were considered to be lead-related. There were 20 Riata (37%) and five (24%) Riata ST indeterminant deaths. In comparison, there were 62 deaths reported for the Quattro Secure lead. Of these, only five (8%) were lead-related and 25 (40%) were indeterminant. Four of the 18 (22%) and three of the four Riata ST (75%) lead-related deaths were associated with can abrasions. In an additional seven patients, insulation defects involving the high-voltage conductors resulted in short circuits and failure to deliver therapy. Can abrasions or deaths caused by short circuiting were not seen with Quattro leads. The major sign of catastrophic Riata and Riata ST lead failures was abnormal high-voltage impedance, which could lead to failure to defibrillate. Three Quattro lead-related deaths were associated with oversensing, indicating a pace sensed conductor failure, and two patients were not rescued due to high-voltage conduction defects.
The authors conclude that Riata and Riata ST ICD leads appear to have a higher risk of high-voltage failure than a comparable lead from another manufacturer. The life-threatening failures were not related to the previously identified problem of externalized conductors. Better methods to detect impending Riata or Riata ST lead failures are needed.
Commentary
When problems with the Riata and Riata ST ICD leads were first reported, most attention focused on the unusual pattern of "inside out abrasion," which led to externalized conductors visible on fluoroscopy in 10-25% of patients. However, these wires have a double insulation and so far, electrical failures have been much less common. The data in this paper, however, suggest that the Riata lead is also prone to other types of failure in the high-voltage circuit. Since these problems may become apparent only when the high-voltage circuit is activated, they are potentially much more dangerous.
The FDA MAUDE database is a very crude tool since it does not collect data in a standardized format. Many problems are thought to be significantly underreported. However, as shown here, the data, if searched diligently, may be helpful in alerting electrophysiologists, companies, and regulators to previously unsuspected problems.
When this paper was first scheduled for publication, St. Jude Medical took the unusual step of criticizing the data and asked that the paper be retracted. In this observer's opinion, for a company to ask that a peer-reviewed paper be retracted is almost always a mistake. Patient safety should always be the top concern. Rather than criticizing a paper, the company should just try harder to collect better data that can be used by clinicians to protect their patients.
The Riata and Riata ST ICD leads manufactured by St. Jude Medical have recently come under increased scrutiny because of the observation that the conductor cables could extrude from the outer insulation.Subscribe Now for Access
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