Clinical Trial of First Pacemaker System Designed for Use in MRI Machines

A clinical trial has been initiated to validate the safety and efficacy of the a pacemaker system, the first-ever to be developed and tested specifically for safe use in magnetic resonance imaging (MRI) machines under specified scanning conditions.

The healthcare company Medtronic, Inc. (Minneapolis, MN, USA) announced the start of the Medtronic EnRhythm MRI SureScan pacing system trail. The EnRhythm MRI SureScan pacing system consists of the dual-chamber EnRhythm MRI SureScan pacemaker and CapSureFix MRI SureScan pacing leads (Model 5086MRI). The first implant in the U.S. clinical trial was performed by Brian Ramza, M.D., Ph.D., director of Electrophysiology Laboratory Services at the Mid America Heart Institute, Saint Luke's Hospital (Kansas City, MO, USA).

Currently, individuals with implanted cardiac devices such as pacemakers, implantable cardioverter-defibrillators (ICDs) and cardiac resynchronization therapy (CRT) devices are prohibited from receiving MRI scans, since MRI machines may interact with traditional systems, potentially compromising therapy and patient safety.

Extensive research and design efforts went into the EnRhythm MRI SureScan pacing system to address and mitigate interactions between the pacing system and the MR environment. The system includes modified hardware to minimize the level of energy transmitted through the lead/device connection point. The pacemaker also includes a new SureScan feature that can be programmed "on” before an MRI scan to eliminate the impact of MRI-generated electrical noise, which can affect pacing therapy. The device and leads also contain radiopaque marks, viewable via X-ray, to indicate that the system is MR-Conditional (a term identifying a device that may be used during an MRI under specified scanning conditions). The CapSureFix MRI SureScan leads are modified versions of the active-fixation Medtronic CapSureFix Novus leads, and are designed to decrease the risk of overheating during an MRI scan without limiting the ability to conduct therapy.

The pacemaker incorporates all diagnostic and therapeutic features of the commercialized Medtronic EnRhythm pacemaker, including an exclusive pacing mode called MVP (managed ventricular pacing), which enables the device to be programmed to deliver pacing pulses to the right ventricle only when necessary. Recent clinical studies have shown that reducing this pacing stimulation may reduce the patient's risk of developing heart failure and atrial fibrillation.

The trial is a prospective, randomized, controlled, unblinded, multi-center study, involving 470 individuals; eligibility is based on the clinical indication for pacemaker implantation and a willingness and ability to undergo elective MRI scanning. All patients in the trial will receive an EnRhythm MRI SureScan pacing system, and two-thirds of the participants will receive MRI scans; the trial's first MRI scans will occur approximately two to three months after device implant. The study will compare the electrical system performance, among patients in both groups. In addition, the study will assess the MRI-related complication rates in the month following the MRI scans. The expected study duration and follow up time is approximately 30 months.


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