Medtronic Micra transcatheter pacemaker meets initial safety and performance measures

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Medtronic reported study results of its Micra transcatheter pacing system (TPS) at a late-breaking clinical trials session at EHRA EUROPACE-CARDIOSTIM 2015 (21–24 June, Milan, Italy). The study results demonstrated that the miniaturised pacemaker met initial safety and performance measures in its global clinical trial.

Of the first 140 patients who received the Micra TPS, 100% were successfully implanted. At one- and three-month follow ups, all patients had mean electrical pacing measurements within expected ranges.

“The initial results for this novel device are quite promising, and similar to results seen with conventional pacemakers,” said Philippe Ritter, principal investigator of the trial and cardiologist at University Hospital of Bordeaux, France. “Patients in this study have fared very well, and if the strong safety and performance profile of the Micra TPS continues with more patients and over the long-term, this transcatheter pacing therapy will prove to be a simpler, less-invasive pacemaker option while maintaining therapy effectiveness.”

The first 140 patients in the Micra TPS Global clinical trial were implanted by 37 physicians at 23 sites across Asia-Pacific, Europe and the USA. They spanned a wide variety of patient profiles such as age (from 21–94 years), weight (ranging from 41–148kg), and residence (including Asia-Pacific, Europe and the USA). Patients considered to be at high risk also participated in the study, including patients with lung disease such as COPD (chronic obstructive pulmonary disease) and pulmonary hypertension.

Of the 140 patients followed for an average of 1.9 months, eight patients experienced a serious adverse event and most of these were easily managed; two patients (1.4%) experienced events which resulted in prolonged hospitalisation. This rate is in line with rates observed in studies of traditional pacemakers. Importantly, there were no infections or dislodgments, and no events required surgical re-operation or resulted in death. Further, there were no unanticipated serious adverse device events (assumed <5%).

Testing of electrical performance at three months showed the pacing threshold was lower (0.51V at 0.24ms) than the pre-specified performance objective (

These initial results from the clinical trial also were published in the European Heart Journal.

At less than one-tenth the size of traditional pacemakers, Medtronic says that the Micra TPS provides the most advanced pacing technology available while being cosmetically invisible and small enough to be delivered with minimally invasive techniques through a catheter, and implanted directly into the heart. The small size and short length of the Micra device allows physicians to implant more than one device within the heart, if needed.

Comparable in size to a large vitamin, the Micra TPS does not require the use of leads to deliver pacing therapy; rather, it is attached to the heart via small tines and delivers electrical impulses that pace the heart through an electrode at the end of the device. Once positioned, the Micra TPS can be repositioned or retrieved, if needed. The device responds to patients’ activity levels by automatically adjusting therapy. Micra TPS also is the first transcatheter pacing system to be awarded CE mark for 1.5T and 3T full body magnetic resonance imaging scanning, providing patients with access to the most advanced imaging diagnostic procedures.

Unlike traditional pacemakers, the Micra TPS does not require a surgical pocket under the skin, so potential sources of complications from this type of implantation are eliminated, as are any visible signs of the device.

The Micra TPS was commercially launched in Europe earlier this month after being awarded CE mark based on data from the Medtronic Micra TPS Global Clinical Trial. The trial is ongoing and will continue to evaluate the safety and efficacy of the device through a single-arm, multicentre study that has enrolled more than 700 patients at 56 centres in 19 countries. In the USA, the Micra is an investigational device and not yet approved for commercial use.

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