A new study that confirms the high rate of an erosion problem that led to the recall of St. Jude’s Riata heart defibrillator leads has found that such failures are most likely to occur with wires that have large diameters. Results of the study indicated that inside-out erosion occurred in 9.3 percent of the smaller diameter Riata ST 7F leads, versus 24 percent of the larger diameter Riata 8F leads.
St. Jude stopped selling the Riata line of defibrillator leads in late 2010, and warned doctors not to use them because they were poking through their insulation. Such a defect can cause a defibrillator to emit unnecessary shocks to a patient’s heart, and even worse, fail to emit a life-saving electrical impulse to the heart when it’s needed. In December 2011, the U.S. Food & Drug Administration deemed St. Jude’s action a Class I medical device recall, its most serious type of recall.
This new study, launched by St. Jude in the wake of the sales suspension, followed 718 patients implanted with the Riata leads at 20 US and Canadian sites. Another 51 patients were enrolled in Japan. Overall, Riata leads broke through their insulation in 19% of the defibrillator patients included in the study.
“The rates of externalized conductors in this study are consistent with other published studies involving fluoroscopic screening of patients with Riata leads. This study also reinforces that externalized conductors are more prevalent in larger-diameter Riata leads,” Dr. Mark Carlson, chief medical officer and senior vice president of clinical affairs for the St. Jude Medical Cardiac Rhythm Management Division, said in a statement issued by St. Jude. “We are now focused on collecting longer-term data in the second phase of this study. Our goal is to provide physicians timely and relevant clinical data to best support their patient management decisions.”
According to St. Jude, the study will continue for two years to determine the rate of electrical failures that can lead to fatal short circuits. In March, Minneapolis cardiologist Dr. Robert Hauser published a study in Heart Rhythm Journal that connected electrical failures of the Riata lead to at least 20 deaths. St. Jude disputed those findings and sought to have the study retracted, but the journal refused.
It is estimated that Riata leads are implanted in some 78,000 U.S. patients. Doctors have been advised to monitor patients with Riata for signs of lead failure.