Medtronic's Micra Transcatheter Pacing System Meets Safety and Effectiveness Endpoints in Global Trial

November 9, 2015—Medtronic plc announced the publication of data demonstrating that the company’s Micra transcatheter pacing system (TPS) was successfully implanted in 99.2% of patients in the trial and met its safety and effectiveness endpoints with wide margins. These data, from the Medtronic Micra TPS Global Clinical Trial, were presented during a late-breaking Special Report session at the American Heart Association’s (AHA) Scientific Sessions 2015 being held November 7–11 in Orlando, Florida, and simultaneously published by the trial’s Principal Investigator Dwight Reynolds, MD, et al in The New England Journal of Medicine.

In Medtronic’s press release, Dr. Reynolds, who is Regents professor and Chief of the Cardiovascular Section at the University of Oklahoma Health Sciences Center in Oklahoma City, Oklahoma, commented, “We are extremely pleased with the remarkably successful implant rates and safety profile of the Micra pacemaker, including the absence of device dislodgments. We are especially confident in these results because the trial included patients with serious comorbidities from 19 countries on five continents around the world. The Micra TPS not only met its trial endpoints, but also provided a significant reduction in health care utilization due to fewer major complications compared to conventional pacing systems, which is particularly important in an era of value-based healthcare.”

Medtronic reported that in the Micra trial, 96% of patients (700 of 725; 6-month Kaplan-Meier estimate) experienced no major complications, which is significantly fewer (51% fewer) major complications than seen in patients with conventional pacing systems (hazard ratio: 0.49; 95% confidence interval [CI], 0.33 to 0.75; P = .001). Major complications included cardiac injuries (1.6%), complications at the groin site (0.7%), and pacing issues (0.3%). Notably, there were no dislodgments, no systemic infections, and very few (0.4%) system revisions (meaning extraction, repositioning, or replacement). 

The company noted that these low complication rates were achieved despite the inclusion of high-risk patients worldwide, including patients with chronic obstructive pulmonary disease.

The presentation included a comparison of Micra TPS safety performance to a predefined, historical control group consisting of more than 2,500 patients from six studies of commercially available, conventional pacing systems. Compared to patients with conventional systems, the patients in the Micra trial were older and had more comorbidities, yet had fewer major complications.

Almost all patients in the trial, 98.3% (292 of 297), had low and stable pacing thresholds at 6 months, yielding projected average longevity for the device to more than 12 years (300 patients at 6 months).

In addition, the low major complication rates experienced by Micra patients resulted in significant reductions in health care utilization compared to conventional pacing systems: Micra patients had 54% fewer hospitalizations (P = .011) and 87% fewer system revisions (P < .001) than observed in the historical control group.

The trial, which enrolled 744 patients, is ongoing and will continue to evaluate the safety and efficacy of the device through a single-arm, multicenter study at 56 centers in 19 countries. Primary endpoints of the trial were freedom from device-related or procedure-related major complications, with target performance of > 90% (lower CI > 83%) at 6 months, and low and stable pacing thresholds as demonstrated by ≤ 2V and no increase of > 1.5V (relative to implant) and target performance of > 89% (lower CI > 80%) in the first 300 patients at 6 months.

Medtronic stated that the Micra TPA is less than one-tenth the size of traditional pacemakers while providing the most advanced pacing technology available. The Micra TPS does not require the use of leads to deliver pacing therapy; rather, its flexible tines attach to the interior of the right ventricle. The tines can be disengaged during the implantation process without causing trauma to the cardiac tissue, allowing the device to be repositioned during implantation and retrieved if needed.

In April 2015, Micra TPS received European CE Mark approval for 1.5T and 3T full body magnetic resonance imaging scanning based on earlier data from the Medtronic Micra TPS Global Clinical Trial. In the United States, the Micra TPS is an investigational device and not yet approved for commercial use.