Leadless Pacemakers “Lead” the Way to Fewer Complications in Cardiac Arrhythmias

Of the 1 million individuals worldwide who undergo transvenous pacemaker (TVP) implantation each year, up to 12% experience complications related to the device.^1-3 These include acute complications such as pneumothorax and cardiac perforation, and long-term complications such as infection, pocket erosion, and lead fracture.

The recently introduced leadless cardiac pacemakers (LCPs) were “developed to mitigate complications by eliminating the need for a subcutaneous pocket and transvenous leads,” wrote the authors of a study published in Heart Rhythm.¹ “These devices are small (~1 cm³), entirely self-contained units that are delivered via a transfemoral venous catheter and affixed in the right ventricle” via an active or a passive fixation mechanism.

After earlier results of nonrandomized comparison studies^4,5 demonstrating the short-term safety and efficacy of LCPs, the current investigators compared the short-term and midterm complications of LCPs with those of single-chamber TVPs.¹ They collected LCP safety data (n=718; mean age 75.6±11.9 years; 62% men) from follow-up observations of a previous study, and TVP safety data (n=1436; mean age, 76.1±12.3 years; 63% men) were based on a propensity score-matched cohort derived from a large insurance claims database.

In the LCP cohort compared with the TVP cohort, there were fewer complications (hazard ratio, 0.44; 95% CI, 0.32-0.60; P <.001), both in the short-term (5.8% vs 9.4%; P =.01) and midterm (0.56% vs 4.9%; P <.001) events. However, more pericardial effusions occurred in patients with LCPs in the short-term (1.53% vs 0.35%; P =.005). There were comparable rates of vascular events (1.11% vs 0.42%; P =.085), dislodgments (0.97% vs 1.39%; P =.54), and generator complications (0.70% vs 0.28%; P =.17) between cohorts. No thoracic trauma occurred in the LCP group compared with a rate of 3.27% in patients with TVPs.

“The overall reduction in both short- and mid-term events was driven by a virtual elimination of lead, pocket, and infectious complications, suggesting that this disruptive technology has successfully targeted the most common sources of traditional pacemaker complications observed over the past 50 years,” the authors concluded.

As described in a recent press release, 1 of the first patients who underwent LCP implantation at the Cleveland Clinic in Ohio had twice experienced lead-related complications previously with a TVP.⁶ The first time, after noticing facial swelling and redness during her workouts, physicians determined that 1 of her TVP leads had caused a collapsed vein that was restricting blood flow. A few years after a surgeon removed the lead, performed a balloon angioplasty, and reactivated the TVP, the patient’s symptoms recurred because of a blockage caused by the remaining lead.

At that point, the patient was initially scheduled to undergo external pacemaker implantation when her electrophysiologist at Cleveland Clinic informed her that she was eligible to participate in a trial testing LCPs, and she immediately agreed. Her TVP was removed, and she again underwent balloon angioplasty before the LCP was inserted. In the subsequent 4 years, she has resumed her workout regimen of 4 to 5 sessions per week and has not experienced any complications related to her pacemaker.

The researchers noted, however, that although the results thus far are encouraging, the long-term comparative effects of LCPs will not be elucidated for at least a decade.

Cardiology Advisor reached out to the study’s lead investigator, Daniel J. Cantillon, MD, FACC, FHRS, electrophysiologist at the Heart & Vascular Institute at Cleveland Clinic, for a brief discussion about his findings.

Cardiology Advisor: What are the top advantages and disadvantages of leadless vs conventional pacemakers?

Dr Cantillon: The major advantage is complete elimination of lead- and pocket-related complications, which account for the overwhelming majority of pacemaker-related complications. The principal disadvantage is a small increase in pericardial effusion related to the use of a completely new, first-generation technology. The encouraging finding is that operator experience makes a big difference, as our study showed that the complication rate from leadless pacemakers is nearly halved after just 10 successful implants. In addition, anticipated technical refinements on future generations of leadless pacemakers are expected to further improve the delivery and retrieval procedures.

Cardiology Advisor: Are there some patients for whom leadless pacemakers are not recommended?

Dr Cantillon: At this time, leadless pacemakers are limited to patients requiring single chamber pacing only. That accounts for only 10% of patients requiring pacemakers in the United States.

Cardiology Advisor: What should be next steps in terms of research in this area?

Dr Cantillon: Additional research needs are 2-fold. First, iterative technical improvements are needed on the leadless pacemaker delivery and retrieval systems to perform even better than the results seen with the “gen one” technology. Second, [studies should focus on] expansion of leadless pacemakers to include dual-chamber and ultimately cardiac resynchronization pacing needs. The latter will cover the majority of patients needing pacemakers in the United States and worldwide.

Disclosures: The study conducted by Dr Cantillon et al was funded by Abbott. Dr Cantillon is also a consultant for Abbott and Boston Scientific.

References

1. Cantillon D, Dukkipati SR, Ip JH, et al. Comparative study of acute and mid-term complications with leadless and transvenous cardiac pacemakers. Heart Rhythm. 2018;15(7):1023-1030.
2. Kirkfeldt RE, Johansen JB, Nohr EA, Jorgensen OD, Nielsen JC. Complications after cardiac implantable electronic device implantations: an analysis of a complete, nationwide cohort in Denmark. Eur Heart J. 2014;35(18):1186-1194.
3. Udo EO, Zuithoff NP, van Hemel NM, et al. Incidence and predictors of short- and long-term complications in pacemaker therapy: the FOLLOWPACE study. Heart Rhythm. 2012;9(5):728-735.
4. Reddy VY, Exner DV, Cantillon DJ, et al. Percutaneous implantation of an entirely intracardiac leadless pacemaker. N Engl J Med. 2015;373(12):1125-1135.
5. Reynolds D, Duray GZ, Omar R, et al; Micra Transcatheter Pacing Study Group. A leadless intracardiac transcatheter pacing system. N Engl J Med. 2016;374(6):533-541.
6. Study finds leadless pacemakers are minimizing problems for patients [news release]. Cleveland Clinic Newsroom; Cleveland, OH. Published June 26, 2018. https://newsroom.clevelandclinic.org/2018/06/26/study-finds-leadless-pacemakers-are-minimizing-problems-for-patients/. Accessed on September 14, 2018.6.