Letter from the Section Editor: Device Therapy

DOI: 10.19102/icrm.2011.020312

Ulrika Birgersdotter-Green, MD, FACC, FHRS

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Device Therapy

On behalf of Dr. John Day, the editorial board, and my section co-editors, I enthusiastically introduce you to the new and exciting section of Device Therapy within The Journal of Innovations in Cardiac Rhythm Management. This section will provide a gateway for clinicians and researchers to publish manuscripts that examine original findings, emerging techniques and novel technologies that impact our understanding and utilization of devices that treat cardiac conduction abnormalities, arrhythmias, and heart failure.

The field of cardiac device and therapy has seen numerous evolutions and advancements in recent years, including the availability of newly FDA approved MRI compatible pacemakers, as well as new recommendations to incorporate implantation of devices for cardiac resynchronization therapy in patients with minimal heart failure symptoms. The emergence of a totally subcutaneous system of automatic implantable cardioverter-defibrillators (ICD) provides an attractive alternative to the transvenous system in prevention and treatment of ventricular arrhythmias. In addition, refined and advanced techniques of lead extraction have gained great enthusiasm in face of the increasing need.

The MRI-compatible En-rhythm pacemaker system from Medtronic Inc. has garnered significant attention in the news recently. In 464 patients implanted at 41 centers in the US, Europe, Canada, and Middle East, there was no MRI-related complication reported before, during, and after an MRI examination.¹ This is the first system to be designed specifically for safe use in a MRI environment. Given the increasing number of people living with cardiac devices, the availability of such a MRI compatible system is certainly of paramount importance.

Also of interest, in a small, nonrandomized study by Bardy et al, an entirely subcutaneous ICD system was shown to consistently detect and treat all episodes of spontaneous sustained ventricular tachyarrhythmia.² Even though there were limitations to the subcutaneous system, such as the lack of long-term pacing and anti-tachycardia pacing, it offers an alternative to the currently conventional transvenous system.

The landmark MADIT-CRT trial enrolled 1820 patients with ischemic or non-ischemic cardiomyopathy, ejection fraction of 30% or less, QRS duration of 130 msec or more, and New York Heart Association class I or II symptoms. The use of CRT combined with an ICD in asymptomatic or mildly symptomatic patients was associated with a 34% reduction in the risk of death or heart failure events.³ This study provides evidence that preventive CRT-ICD therapy decreases the risk of heart-failure events in vulnerable patients who have minimal heart failure symptoms but a wide QRS complex.

The increasing number of implanted cardiac devices over the last two decades has led to the rising need for lead extraction due to structural defects, infection, or necessity to upgrade a pre-existing system. This calls for the development of safe and effective methods. In a recent review on transvenous lead extraction from our institution, including fully integrated webcast videos currently available on the Innovations in Cardiac Rhythm Management website, www.InnovationsCRM.com, we recommend a systemic approach to ensure success and avoid life-threatening complications.⁴

Within this issue we feature a review article entitled, The Implantable Loop Recorder: Current Uses, Future Directions by Kanjwal et al. from the University of Toledo Medical Center. In this paper, Kanjwal et al review the utilization of implantable loop recorders (ILRs) in various clinical settings. In addition, a new method of implantation at their institution is described which results in better P-wave amplitude and less artifacts. The paper also proposes that in selected patients with potentially life-threatening conditions such as long QT syndromes, Brugada syndrome, and hypertrophic cardiomyopathy who do not meet criteria for ICDs but are felt to be at increased risk of sudden cardiac death, the ILR can offer an attractive means for long-term arrhythmic monitoring.

The aforementioned are just a few highlights of the ever evolving field of cardiac device therapy. Our mission is to provide an effective understanding and utilization for cardiac devices to the clinician community. We therefore actively encourage the submission of manuscripts that address the many topics discussed herein. We welcome original manuscripts that bring forth new ideas and innovation to the advancement of cardiac devices.

Ulrika Birgersdotter-Green, MD, FACC, FHRS
E-mail: ubgreen@mail.ucsd.edu
Professor of Medicine
Director of Pacemaker and ICD Clinic
University of California -San Diego
San Diego, CA

References

1. Wilkoff BL, Bello D, Taborsky M, et al. Magnetic resonance imaging in patients with a pacemaker system designed for the magnetic resonance environment. Heart Rhythm 2011; 8:65-73. [CrossRef] [PubMed]
2. Bardy GH, Smith WM, Hood MA, et al. An entirely subcutaneous implantable cardioverter-defibrillator. N Eng J Med 2010; 363:36-44. [CrossRef] [PubMed]
3. Moss AJ, Hall WJ, Cannom DS, et al. Cardiac-resynchronization therapy for the prevention of heart-failure events. N Eng J Med 2009; 361:1329-38. [CrossRef] [PubMed]
4. Varahan SL, Pretorius V, and Birgersdotter-Green U. Transvenous Lead Extraction: a step-by-step approach. J Innovations Cardiac Rhythm Management 2011; 1:145-49. [CrossRef]