Review shows minimal mechanical failures in newer St. Jude leads

Analysis of St. Jude Medical’s Optim-insulated leads reveals low rates of mechanical failures, conductor fractures and all-cause abrasions by five years. “The bottom line of it all is that the results are very good,” the lead researcher told Cardiovascular Business.

These findings, part of ongoing reviews of St. Jude Medical leads, includes Riata ST Optim and Durata leads. Studies of the previous generation of leads led to the prior recall of Riata products.

John A. Cairns, MD, professor of medicine at the University of British Columbia in Vancouver, colleagues at McMaster University and others reviewed data from three registries of St. Jude implants starting in 2006. Cairns said that St. Jude Medical went to McMaster's Population Health Research Institute about two years ago to have the findings independently verified.

“Their [St. Jude Medical’s] impression has been that these leads are performing much better than the earlier renditions,” Cairns said. But, Cairns noted, because it was an internal registry, the company wanted to have an independent analysis.

Since then, the team led by Cairns has reviewed the historical data and updated their findings every six months as follow-up on the leads has continued. The recently published findings include data through February 2013.

As of that point, the median follow-up time was 3.2 years for all Optim leads. The median follow-up time for patients with Durata leads, including DF4 and DF1, was three years and for Riata ST Optim leads, 4.1 years. More than half of patients enrolled were still being actively followed.

Cairns et al determined that all-cause mechanical failure in these leads was 0.46 percent. Conductor fracture occurred in 0.31 percent of leads implanted, 0.1 percent of leads experienced insulation abrasion, and 0.05 percent experienced miscellaneous mechanical lead failure. No externalized conductors were seen among registry patients. Five-year freedom from conductor fracture and insulation abrasion was 99.4 percent and 99.8 percent, respectively.

The  main finding of the analysis is that the Optim family of leads had no report of externalized conductors at median 3.2 years follow-up and that the mechanical failure rate was around 1.5 cases per 1,000 per year.

Cairn characterized the results as "very good. There’s follow-up in some of these patients up to seven years, although in the paper the median is about 3.2 years and the actuarial survivals of these leads free of mechanical failure at five years is extremely good.”

Cairns noted that the problem with earlier-generation leads had been the externalized conductors, which had not occurred in any of the more than 11,000 leads implanted over the course of the data period.

The leads, Cairns stated, were reliable and cardiologists and electrophysiologists should be assured that odds of fractures and abrasions of leads are low in the current generation.

This study was published in the December issue of Heart Rhythm.