Photo: Fractured Riata lead, Univ. of Pittsburgh Medical Center

Data released today by St. Jude Medical (NYSE:STJ) show that persistent problems with its recalled Riata defibrillator leads increased during the 2nd half of last year, even as the company sought to shift the focus to its newer Durata line of leads.

The rate of "conductor fracture" rose 4.3% compared with the company’s last lead performance report issued last November. The rate of "insulation breach" rose 24.4%, and the overall rate of malfunctions rose 12.3%, according to the report issued today.

Sign up to get our free newsletters delivered straight to your inbox

Here’s a look at some key malfunction data for the recalled Riata leads from the St. Jude Medical performance reports released last year and today:

In a statement emailed to MassDevice.com, St. Jude said it took pains to report extra detail in the latest performance report, acknowledging that the reports under-estimate the extent of the problem.

"This is why we have included a special section specifically addressing and providing additional detail regarding the performance of our high-voltage leads in this edition of the PPR," the company said. "We have also expanded our Riata Lead Evaluation Study to include approximately 700 patients, and are in the process of finalizing the initial results regarding the rate of externalized conductors. We expect to have the initial results reporting on the incidence of externalized conductors compiled and communicated before the end of June 2012. The study will continue to follow patients to evaluate the performance of leads that have externalized conductors over the next two years to further inform patient management."

A controversy over the Riata leads made headlines last month when St. Jude and CEO Daniel Starks went to bat to contradict a study by renowned cardiologist Dr. Robert Hauser showing 22 deaths linked to the leads. The data released today seem to confirm that the leads are prone to fracture, especially given that the performance reports under-report the true number of malfunctions. That’s because they only track malfunctions reported to St. Jude by physicians, meaning an unknown number of events go unreported.

"It still is at a fairly low level, but that doesn’t mean we like it," Dr. Bruce Wilkoff, an electrophysiologist at the Cleveland Clinic and a member of St. Jude’s independent medical advisory board, told the Wall Street Journal. "It is by its very nature an under-estimate of the issue."

The Riata affair began in September 2011 with a small Irish study reporting that revision surgeries for the Riata lead were higher than previously reported. A month later, Starks took to the airwaves to inveigh against arch-rival Medtronic (NYSE:MDT) and its alleged attempts to prejudice the market against St. Jude.

Little more than a month after Starks’ challenge, however, the company was forced to concede that the Riata revision rates were higher than previously reported, and in December 2011 the FDA slapped the device with Class I recall status.

St. Jude had already begun phasing out its Riata and Riata ST leads in December 2010 over concerns that their electrical insulation could cause the devices to malfunction, but the FDA didn’t view the matter as a recall-worthy then, a company spokesperson told the Wall Street Journal at the time.

Then, with the online publication in the Heart Rhythm Society’s journal of a study by a prominent cardiologist linking Riata with 22 deaths, things began to get interesting. By late March, St. Jude was disputing the findings of the study, by Dr. Robert Hauser. On Friday, April 6, the company asked that the journal retract the story (a request that was summarily rebuffed), and over the course of the following weekend Starks reiterated his accusation that cross-town rival Medtronic was behind a "whisper campaign" against St. Jude.

Medtronic then released its own analysis confirming Hauser’s count of the number of deaths attributable to its own Quattro leads, engendering a swift and unusual response from St. Jude, which published its own tally of the Quattro deaths.

"I can’t recall seeing a more contentious and open dispute between medical device companies in my 19 years working in this field," Ohio cardiologist Dr. Edward Schloss, director of cardiac electrophysiology at the Christ Hospital in Cincinnati, told MassDevice.com.