August 21st, 2012

New Questions About Latest-Generation ICD Leads from St. Jude

A highly anticipated study analyzing failures of St. Jude Durata and Riata ST Optim ICD leads has been published online in Europace by prominent electrophysiologist and ICD critic Dr. Robert Hauser along with associates from the Minneapolis Heart Institute.

Over the past year St. Jude Medical has been beset with bad news about its ICD leads. Until recently, the criticism was confined to the older-generation Riata and Riata ST leads. These leads have been shown to be prone to both structural and electrical failures at an increased rate compared with competitive leads. St. Jude has staunchly defended its newer-generation Durata and Riata ST Optim leads, which have an additional layer of Optim copolymer insulation coating, which St. Jude believes will reduce failures by improving abrasion resistance. Last week, however, the FDA issued a new request for postmarketing studies, including X-ray surveillance of these leads, calling them “sufficiently similar” to Riata and Riata ST to merit increased scrutiny.

Today’s study from Hauser serves as another blow to St. Jude and may affect implanter confidence in current-generation Durata leads. In the study, Hauser queried the FDA MAUDE database for “abrasion analysis” and reported detailed results. He found 15 Riata ST Optim and 37 Durata reports. The predominant abnormality in both groups was external abrasion (i.e., can/lead or lead/lead), although several internal abrasions were also found. Most of these abrasions resulted in clinically relevant electrical abnormalities such as low voltage oversensing leading to inappropriate shocks. One high-voltage failure during a spontaneous ventricular arrhythmia resulted in an ineffective shock and subsequent patient death.

Hauser shied away from making comparisons with other leads in the current study and did not make any attempt to calculate an incidence of lead failure, recognizing the limitations inherent in analysis of a voluntary database. This stands in contrast to his last Riata/Riata ST MAUDE analysis, which provoked a firestorm of criticism including a request for article retraction from St. Jude Medical.

In comments in the New York Times, Hauser expresses a lack of confidence with Durata: “There is no need to use this lead until we have more confidence in its performance.” Hauser goes on to level direct criticism at Optim insulation, stating “I’m afraid that this material is not going to perform as advertised.”

As a practicing cardiac electrophysiologist and ICD implanter who has followed this matter closely, I’d like to add a few comments of my own.  It’s important for all to realize that no ICD lead is bulletproof.  All will have an incidence of failure including the types of abrasion reported in Hauser’s current study.  It is critical to realize that even poor performing ICD lead models in patients with an appropriate implant indication confer lifesaving protection against sudden cardiac arrest that exceeds medical therapy alone.

St Jude has taken an aggressive stance defending the Durata lead, and from a business standpoint, it is not hard to see why. Along with others who have closely followed this situation, I have criticized this lead, given its significant similarity to the Riata ST lead and have chosen not to implant it. Today’s study is a direct blow to the Optim insulation that St. Jude holds is the key to Durata’s relative performance. If Optim proves to have long-term bio-instability, we can expect this lead to behave similarly to Riata ST.

It is naive to think that any insulation, including Optim, will be 100% immune to abrasion. Today’s study reminds us of that fact. Note, though, that it is impossible to make any assumptions about the overall incidence of Durata and Riata ST Optim failures on the basis of this data. For that reason, I agree that it would be inappropriate to replace or extract these leads in the absence of electrical failure.

Because it is unlikely that Optim will worsen ICD lead performance, it should be reasonable to expect these leads to behave like Riata ST in their early life. Failures in these leads tend to accelerate about four years after implantation. As the first implanted Durata leads are only now reaching that stage, the jury on this lead will remain out for some time.

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