Wall Street didn’t move much on news of another insulation-related failure in St. Jude Medical’s (NYSE:STJ) next-generation Durata defibrillator leads this week.

The case report included a detailed analysis of an incident in which a Durata lead failed due to inside-out abrasion, which some likened to the externalization issues that launched the high-profile recall of St. Jude’s older Riata leads.

"This most recent ICD lead failure suggests that the Durata lead can fail in a manner similar to the recalled Riata and Riata ST leads," Ohio electrophysiologist Dr. Edward Schloss wrote in a guest post published on CardioBrief. "All eyes will be watching to see if this is an isolated event, or represents an early sign of systemic trouble for this lead."

The study was published this week in the journal Heart Rhythm, the same journal that around this time last year was at the center of the dramatic foofaraw over a study linking the older Riata lead with 22 deaths. St. Jude disputed the findings of that study and asked that the journal retract the story, a request which was summarily rebuffed.

Dr. Schloss kept a close eye on the commotion, telling MassDevice.com at the time that it was unlike anything he’d seen in nearly 20 years of practicing medicine.

The latest Durata failure news didn’t appear to stir much attention from Wall Street, where yesterday’s 2.3% drop in STJ seemed more the result of a senior note offering than of the Durata report. STJ shares have slowly lost about 4.6% over the course of this week, but it’s unclear whether much of that has to do with the Heart Rhythm report.

The Durata lead in the case report was implanted in January 2008 and began to have issues in July 2010, Schloss wrote. The lead was ultimately removed in January 2013, at which time the researchers found internal abrasion in the insulation as well as degradation in the outer insulation.

"Analysis of the lead after removal showed several area of insulation degradation. There were areas of visible abraded internal silicon and ETFE insulation under the distal shocking coil that resulted in electrical over-sensing due to contact between the ring sensing cable and coil," Schloss wrote. "In addition, several areas of degradation of the Optim outer insulation were found at sites of lead flexion. Based on detailed failure analysis, the investigators concluded that the lead failed due to inside-out abrasion of the silicon inner core of the lead."

St. Jude’s spokespeople didn’t attempt to dispute the study in speaking with MassDevice.com today, but noted that the failure described in the case report is a known and very rare issue in the Durata leads, which feature an Optim coating that is designed to be more resistant to abrasion. The case report also depicted a case of under-the-shock-coil abrasion, different from the lead externalization reported with the Riata and Riata ST leads, Meyer said.

"St. Jude Medical proactively reports all known lead failures in our comprehensive biannual product performance report, including the very rare failure type of under-the-shock-coil abrasion identified in this case report," spokeswoman Amy Jo Meyer told us. "In our last PPR, we reported that the incidence rate of this failure mechanism in Durata leads remains very low."

The medical device maker plans to update its PPR data this May, and will include this latest Durata incident report, Meyer said. Current data supports the "excellent performance" of Durata and other Optim-insulated leads, she added.

St. Jude has been attempting to shield its Durata leads from the high-profile recall of its Riata and Riata ST leads, which were pulled from shelves after the company was forced to concede that the Riata revision rates were higher than previously reported. In December 2011 the FDA gave the recall Class I status, the highest-risk category for medical device recalls.

St. Jude has been busy ever since calming fears about the next-generation Durata leads, and some analysts have said that a Durata recall is not likely, even as a handful of negative reports created some waves on Wall Street. Others, such as the analysts at Citigroup, think a recall is more likely, if not downright probable.

Wall Street investors are keeping their eyes peeled for any sign of a problem with the Durata leads. In June 2012, a single report (later debunked) of a Durata lead failure similar to the kind that sank the Riata sent STJ shares plunging 6% in a single day.