Early performance of a miniaturized leadless cardiac pacemaker: the Micra Transcatheter Pacing Study

• Published in: European heart journal Vol. 36; no. 37; pp. 2510 - 2519
• Main Authors: Ritter, Philippe, Duray, Gabor Z., Steinwender, Clemens, Soejima, Kyoko, Omar, Razali, Mont, Lluís, Boersma, Lucas VA, Knops, Reinoud E., Chinitz, Larry, Zhang, Shu, Narasimhan, Calambur, Hummel, John, Lloyd, Michael, Simmers, Timothy Alexander, Voigt, Andrew, Laager, Verla, Stromberg, Kurt, Bonner, Matthew D., Sheldon, Todd J., Reynolds, Dwight
• Format: Journal Article
• Language: English
• Published: England Oxford University Press 01.10.2015
• Series: Editor's choice
• Subjects: Aged; Atrioventricular Block - therapy; Clinical Research; Electrocardiography, Ambulatory; Female; Humans; Male; Microelectrodes; Operative Time; Pacemaker, Artificial; Patient Safety; Prospective Studies; Prosthesis Design; Prosthesis Implantation - methods; Sick Sinus Syndrome - therapy; Treatment Outcome; Leadless cardiac pacemaker; Transcatheter pacing system; Miniaturization
• ISSN: 0195-668X; 1522-9645; 1522-9645
• DOI: 10.1093/eurheartj/ehv214

Permanent cardiac pacing is the only effective treatment for symptomatic bradycardia, but complications associated with conventional transvenous pacing systems are commonly related to the pacing lead and pocket. We describe the early performance of a novel self-contained miniaturized pacemaker. Patients having Class I or II indication for VVI pacing underwent implantation of a Micra transcatheter pacing system, from the femoral vein and fixated in the right ventricle using four protractible nitinol tines. Prespecified objectives were >85% freedom from unanticipated serious adverse device events (safety) and <2 V 3-month mean pacing capture threshold at 0.24 ms pulse width (efficacy). Patients were implanted (n = 140) from 23 centres in 11 countries (61% male, age 77.0 ± 10.2 years) for atrioventricular block (66%) or sinus node dysfunction (29%) indications. During mean follow-up of 1.9 ± 1.8 months, the safety endpoint was met with no unanticipated serious adverse device events. Thirty adverse events related to the system or procedure occurred, mostly due to transient dysrhythmias or femoral access complications. One pericardial effusion without tamponade occurred after 18 device deployments. In 60 patients followed to 3 months, mean pacing threshold was 0.51 ± 0.22 V, and no threshold was ≥2 V, meeting the efficacy endpoint (P < 0.001). Average R-wave was 16.1 ± 5.2 mV and impedance was 650.7 ± 130 ohms. Early assessment shows the transcatheter pacemaker can safely and effectively be applied. Long-term safety and benefit of the pacemaker will further be evaluated in the trial. ClinicalTrials.gov ID NCT02004873.