Initial Global Clinical Trial Data Reported for Medtronic's Micra Transcatheter Pacing System

May 15, 2015—Medtronic plc announced that study results for its Micra transcatheter pacing system (TPS) were presented during a Late-Breaking Clinical Trials session at Heart Rhythm 2015, the Heart Rhythm Society’s 36th Annual Scientific Sessions in Boston, Massachusetts.

The Medtronic Micra TPS global clinical trial data are from the trial’s first device implantations performed on 140 patients by 37 physicians at 23 sites in Asia-Pacific, Europe, and the United States.

This study population included a wide variety of patient profiles such as age (21–94 years), weight (range, 41–148 kg; 90–326 lb), and residence (Asia-Pacific, Europe, and the United States). Patients considered to be at high risk also participated in the study, including those with lung disease such as chronic obstructive pulmonary disease and pulmonary hypertension.

The company reported that there was 100% procedural success and that mean electrical pacing measurements at all patients’ 1- and 3-month follow-up were within expected ranges.  The 140 patients were followed for an average of 1.9 months and up to a maximum of 6.5 months.

The investigators found that there were 30 adverse events but most of these were easily managed. There were no apparent differences in the risk of adverse events across the various patient subgroups, such as gender, age, size (body mass index), disease history, or other baseline factors.

Of 140 patients, eight patients experienced a serious adverse event. Despite the broad inclusion criteria, only two patients (1.4%) experienced events that resulted in prolonged hospitalization, a rate that is in line with rates observed in studies of traditional pacemakers.

Furthermore, there were no infections or dislodgments, no events that required surgical reoperation or resulted in death, and no unanticipated serious adverse device events (assumed < 5%).

Testing of electrical performance at 3 months showed the pacing threshold was lower (0.51 V at 0.24 ms) than the prespecified performance objective (< 2 V at 0.24 ms), resulting in an expected average longevity of at least 10 years, noted the company.

Medtronic advised that the results demonstrated that the miniaturized pacemaker has met its initial safety and performance measures. The single-arm, multicenter trial is ongoing and will continue to evaluate the safety and efficacy of the device in more than 700 patients enrolled at 56 centers in 19 countries.

In a separate presentation at Heart Rhythm 2015, results were released on the magnetic resonance imaging (MRI) compatibility of the new transcatheter pacemaker. The data showed that patients with one or more Micra TPS devices can safely undergo full-body scans in 1.5-T and 3-T MRI scanners. MRI compatibility was evaluated using methods similar to tests for traditional pacemaker systems, and it was found that the MRI risk with Micra TPS is greatly reduced compared to traditional MR-conditional pacemaker systems because of the small device size and absence of leads, stated Medtronic.

In Medtronic’s press release, Philippe Ritter, MD, commented, “These initial data are quite promising, as patients in this study have fared very well with this novel device. If the strong safety and performance profile of the Micra TPS that we’ve seen so far persists over the long term and in more patients, this transcatheter pacing therapy will prove to be an effective but simpler and less-invasive pacemaker option for many patients.” Dr. Ritter, who serves as a principal investigator of the Micra TPS global trial, is a cardiologist at Centre Hospitalier Universitaire Bordeaux in Bordeaux, France.

Also in Medtronic's announcement, L.V.A. Boersma, MD, stated, “These initial positive results from the Micra TPS are very encouraging, as they demonstrate safe delivery via the femoral vein and placement within the heart in a wide range of patients from diverse geographies. The strong initial safety data show the potential benefits of the pacemaker system's unique design, including secure attachment to the heart wall along with easy and safe deployment.” Dr. Boersma is a principal investigator of the trial and a cardiologist at St. Antonius Ziekenhuis in Nieuwegein, The Netherlands.

Based on the data from the global clinical trial, the Micra TPS received European CE Mark approval in April 2015. The approval allows for 1.5-T and 3-T full-body MRI scans. In the United States, the Micra TPS is an investigational device and is not approved for commercial use.