Trials at University Hospitals Harrington Heart & Vascular Institute Advance Leadless Pacemakers and Extravascular ICDs

Innovations in Cardiovascular Medicine & Surgery | March 2025

Physician-scientists at University Hospitals (UH) Harrington Heart & Vascular Institute have long been at the forefront of investigating pacemakers and implantable cardioverter-defibrillators (ICDs). These physicians participated in two investigational device exemption trials that helped bring to market novel leadless pacemakers and extravascular ICDs (EV-ICDs). The devices under investigation were:

• Abbott’s Aveir™ VR Leadless Pacemaker 
• Medtronic’s Aurora EV-ICD™ System

Judith Mackall, MD

“Leadless pacemakers and an extravascular ICD that can deliver pacing therapy represent significant advancements in cardiac rhythm management,” says Judith Mackall, MD, Spitz Master Clinician in Cardiology and Medical Director of the Cardiac Device Clinic and the Clinical Trials Unit at UH Harrington Heart & Vascular Institute. “Devices that don’t rely on leads positioned in the vasculature carry less procedural risk and, for leadless pacemakers, a quicker recovery. Each patient should receive a tailored recommendation for their pacing needs, including evaluation for leadless or extravascular options.”

Leadless pacemakers simplify implantation and improve patient comfort. They also eliminate the need for transvenous leads, reducing the risk of complications, including infection, thrombosis and lead fracture. 

EV-ICDs are positioned outside the vascular space, addressing the limitations of transvenous ICDs by avoiding major intravascular complications and providing safe and effective defibrillation with improved pacing capabilities. These innovative devices expand therapeutic options, particularly for younger patients and those with challenging vascular access or increased infection risk.

Evolution of Leadless Pacemakers

Clinical trials for leadless pacing began in 2012. By 2016, the Medtronic Micra VR pacemaker received FDA approval. The Abbot Aveir VR was approved in 2022.

“This has been an amazing step forward in pacemaker technology, and UH Harrington Heart & Vascular Institute has been involved in establishing device safety and efficacy from the beginning,” says Dr. Mackall, who is also the Moll Professor of Medicine at Case Western Reserve University School of Medicine. 

Studies demonstrate that leadless innovations show significant risk reductions compared to transvenous pacemakers. “Implantation of a traditional transvenous pacemaker is associated with a procedural risk of 4 to 8 percent, which is primarily related to the lead and the pacemaker pocket,” Dr. Mackall says. “Over the long-term, an additional 9 to10 percent of patients will experience an issue with their system, and these are usually related to the leads. The need to remove or replace leads can carry substantial risk, including death.”

Dual Pacing Solutions

Abbott’s Aveir DR system is revolutionizing cardiac care by offering single- and dual-chamber leadless pacing. The modular devices can be utilized individually or work together as both atrial and ventricular pacemakers. “They can function independently in patients needing single chamber pacing or communicate to provide synchrony between the heart’s top and bottom chambers,” Dr. Mackall says.

Smaller than AAA batteries, the minimally invasive wireless devices are able to treat a range of slow or abnormal heart rhythms. “These are the world’s first dual chamber leadless pacemakers,” Dr. Mackall says. “This is a lovely advancement for patients, and we have implanters throughout our UH system offering this option to eligible patients.”

Extravascular ICDs

Extravascular defibrillators treat sudden cardiac arrest and tachycardia while reducing the risk of lead-related complications, including venous occlusion and endocarditis. The extravascular approach reduces long-term, lead-related morbidity, which is of particular concern in younger patients who may require multiple device revisions over their lifetime. 

• Boston Scientific’s EMBLEM MRI-ICD was approved by the U.S. Food and Drug Administration in 2016 as the first subcutaneous implantable defibrillator. It is placed above the sternum and has been implanted in more than 150,000 patients worldwide.
• Medtronic’s Aurora EV-ICD system is the first to provide the benefits of conventional transvenous ICDs utilizing a thin lead placed under the sternum. Similar in size and shape to a traditional transvenous ICD, the Aurora system was found in pivotal trial results to be 98.7 percent effective in delivering defibrillation therapy. 

A significant difference between the two systems is lead placement. “With Medtronic’s device, the amount of energy required to defibrillate the heart is much lower because the signal doesn’t need to go through the bone or lung, and its location adjacent to the heart permits antitachycardia pacing if needed,” Dr. Mackall says. “We are able to offer both of these options to patients throughout our system.”

UH Harrington Heart & Vascular Institute participated in the Aurora EV-ICD clinical trial, and Sergio Thal, MD, was UH’s principal investigator (PI).

UH Continues to Drive Leadless Therapy and Extravascular Cardiac Care

The UH Clinical Research Center is well-positioned to engage with industry partners looking to test novel devices. “We have dedicated study coordinators who understand the value of moving technology forward,” Dr. Mackall says. “We always want our patients to have access to the latest and greatest, so when we see something coming that can improve safety and outcomes, it is easy to be excited about participating.”

For more information, contact Dr. Mackall at Judith.Mackall@UHhospitals.org.

Contributing Expert:
Judith Mackall, MD
Director, Cardiac Device Clinic
Director, Clinical Trials Unit
Spitz Master Clinician in Cardiology
University Hospitals Harrington Heart & Vascular Institute 
Moll Professor of Medicine
Case Western Reserve University School of Medicine