Aveir VR leadless pacemaker: interview with professor Tom Wong

KEYWORDS:

• Arrhythmia
• bradycardia
• leadless pacemaker

1. Introduction

Professor Tom Wong is a consultant cardiologist and electrophysiologist at Royal Brompton and Harefield hospitals, focusing on the best ways to deliver care to patients with heart rhythm abnormalities. We sat down with him to discuss the current management and treatment of bradycardia, the Aveir™ VR leadless pacemaker developed by the global healthcare company Abbott, the published results of the AVEIR DR i2i™ Investigational Device Exemption study [1], and what leadless pacemaker technology could mean for bradycardia treatment in the future.

1.1. Could you give us a brief overview of your clinical training and your specific research interests within the field of cardiology?

My basic medical training was in Scotland (University of Aberdeen and Ninewells Hospital in Dundee) prior to my cardiology training in London (Hammersmith, Royal Brompton, and St. Mary’s Hospitals). This was followed by my appointment as a consultant cardiologist and electrophysiologist at Royal Brompton and Harefield hospitals, now part of the Guy’s and St Thomas’ NHS Foundation Trust.

My research interests, aligned with my clinical interest, are in the area of arrhythmia interventions, catheter intervention to treat arrhythmias, atrial appendage management in patients with atrial fibrillation, and implantable electronic devices for cardiac therapy which is particularly relevant to today’s interview! I am very much interested in the innovation technology aspects of arrhythmia care which is an integral part of our work.

I first started my journey with leadless pacemakers about 10 years ago, when the first leadless pacemaker came to market, I was very much involved then, as I am now!

1.2. Could you give us a brief overview of bradycardia/arrhythmia in your own words and based on your own clinical experience?

Bradycardia is a medical term to describe a slow resting heart rate. This is not necessarily an illness – in many individuals, for example athletes, their resting heart rate can be slow (less than 60 bpm) and they function completely normally. However, in other people, a slow heart rate can be a health issue. These individuals may not feel well, in which case, a pacemaker may be a helpful therapy.

1.3. Can you describe the symptoms/clinical indicators that would lead to insertion of a pacemaker?

Individuals with a slow heart rate can have a varying degree of symptoms. At one end of the spectrum, they may be completely asymptomatic. On the other hand, they may present symptoms such as tiredness, dizziness, and fainting. They may even develop heart failure or cardiogenic shock, which is a life-threatening condition. Those individuals with symptomatic slow heart rates will often require pacemakers. In addition, asymptomatic individuals may also require a pacemaker in situations where they have conditions, such as heart block, where an asymptomatic slow heart rate is likely to develop these harmful symptoms.

1.4. What percentage bradycardia patients go on to require a pacemaker?

There is no fixed number as it largely depends on clinical context. As I mentioned earlier, some individuals, such as athletes, will rarely need implantation. Whereas, in symptomatic patients – especially those with heart block, pacemaker therapy is very common.

1.5. How does the Aveir VR leadless pacemaker work?

The Aveir VR leadless pacemaker, is unlike the conventional pacemaker we have come to know in recent years. Conventional pacemakers are placed under the skin, outside of the thoracic cavity, which is then attached to a lead (or multiple leads) where the tip is in contact with the heart. This tip senses the heartbeat and paces when necessary. In contrast, the leadless pacemaker is a self-contained unit placed within the heart’s chamber with the helix tip fixed to the heart muscle to provide the pacing function.

1.6. You have already touched on how the Aveir VR leadless pacemaker differs from conventional pacemakers regarding its leadless technology. So, I was just wondering if there were any other aspects of the Aveir VR leadless pacemaker that are unique to other pacemakers currently on the market?

Aveir VR has several unique features that many, including myself, perceive as desirable. One of these features is the ability to map the appropriate location of the heart before we attach the helix tip to the myocardium. This is a particularly desirable feature of the Aveir VR leadless pacemaker because all hearts are different. Patients who require pacing may have an existing cardiac condition which means that not all sites within the heart are suitable for pacing. So, before the helix is deployed, we can actually identify the most suitable location.

Secondly is the battery capacity of the Aveir VR leadless pacemaker, which is the largest on the market with extended longevity.

In addition, the fixation mechanism of the tip, which I mentioned previously, uses a helix. In terms of leadless pacemakers on the market, the Aveir VR leadless pacemaker is the only one using the helix tip-fixation mechanism. This is advantageous as the pacemaker can be removed by unscrewing the helix many years later if the battery has depleted. There are reports showing that it is feasible to remove the Aveir VR leadless pacemaker many years later – up to 9 years [2].

Another unique feature is the temperature sensing capabilities of the Aveir VR leadless pacemaker. It can sense minute changes in the body’s temperature to adjust the pacing rate. For instance, if we are very active, our temperature tends to be slightly higher than the baseline. This change in temperature will assist the pacemaker to pace the heart a little bit faster to provide the adequate rate required.

The final point I would like to touch upon with regard to the differences between the Aveir VR leadless and others on the market is that the Aveir VR leadless pacemaker has the potential to be upgraded to a dual chamber leadless pacemaker. This technology is just around the corner in the UK and Europe and has been approved in the U.S. already.

1.7. You mentioned that the Aveir VR leadless pacemaker allows for contact mapping before insertion, in your experience as an implanter can you tell us about pacemaker repositioning and the impact that mapping has on implant success in a bit more detail?

Yes, contact mapping is a unique feature of the Aveir VR leadless pacemaker. The mapping capability means we are able to predict the most suitable locations of the heart for full deployment of the device ahead of time. This avoids unnecessary deployment which is commonly known to be related to increased complications. The fewer failed deployment attempts, the safer the procedure, and mapping is very helpful in this context.

1.8. Are there patients with bradycardia who wouldn’t be suitable for the Aveir leadless pacemaker, or are there any contraindications for the device?

Yes, many of the contraindications are shared with the lead-based, conventional pacemaker. For instance, a contraindication would be if there is no vascular access to the heart – the right side of the heart in particular, as this is where we would want to place the Aveir VR leadless pacemaker.

Other contraindications include patients with complex congenital heart disease, for example, with a single ventricle, or patients with a mechanical tricuspid valve, for instance, as it would not be feasible to place the device (leaded or leadless) in the right ventricle.

There may also be relative contraindications for leadless devices in patients, for instance, with heart failure. This is due to the fact that these patients will require a lot of pacing, particularly in patients with branch block. These patients will benefit from a defibrillator function. However, each patient and their treatment needs are different. It’s important for a cardiologists and physicians to work closely to ensure patients receive proper treatment.

1.9. What challenges still remain within treating/managing patients with bradycardia?

This is an excellent question – we have come a long way over the past decades in providing advanced pacing to patients! The leadless technology is a great improvement in our journey. It has significantly reduced infection rates related to the generator pockets and lead related complications.

Aveir VR’s projected battery life is up to two times longer than other currently commercially available leadless pacemakers when using International Organization for Standardization (ISO) standard settings (Tested at VVIR 60 bpm, 2.5 V, 0.4 ms, 600 ohms at 100% pacing).

Having said that, engineers are continuing to innovate and discover a way to further extend battery life such as charging solutions for leadless pacemakers. We are still relying on this finite battery longevity as there is no rechargeable option for the leadless devices. Many patients have asked me ‘Why we do not provide a battery that can be recharged? Why do we have to take it out?.’ It is an excellent point as so many electronics these days can be recharged, why not the pacing battery – that is for the engineers to work on in the future.

Another aspect is physiologic pacing – we are advanced enough now that we can tap into the normal conduction system of the heart to pace accordingly. This is a breakthrough feature, and I am certainly looking forward to the next steps where leadless devices are able to provide this. These are exciting features to come in the future, no doubt.

1.10. The Aveir VR has been designed to be upgraded to a dual chamber system, as you mentioned earlier, and the prospective study for this was published in May – could you tell us about that trial and what the initial data shows?

The landmark publication was published in the New England Journal of Medicine in May 2023 reporting the first-in-human prospective multi-center study to assess the safety and performance of a dual chamber leadless pacemaker system [1]. This system has two individual devices placed in the right ventricle and right atrium that communicate constantly, 24/7, to provide sequential pacing between the two chambers. This is a leap in technology in the leadless pacemaker platform.

A total of 300 people were enrolled and implantation was attempted across 55 centers in the U.S., Canada and Europe and our center was a part of this study. The successful implant rate was very respectable (98.3%), where both devices were successfully implanted in the patient and could communicate at the time of implantation. The primary safety endpoint was met in 90.3% of patients within 90 days. The atrial leadless pacemaker electrical performance matrix was met in 90.2% of patients and in 97.3% of patients, the atrioventricular synchrony matrix was met. This paper concluded that a dual chamber leadless pacing system (AVEIR DR) met the primary safety endpoint and provided atrial pacing and reliable atrioventricular synchrony for 3-months after implantation.

This is a leap in technology! We now have a way to communicate between two individual leadless pacemakers within the heart. This is an amazing platform for us to work on and to build on in terms of future pacing ventures that we can develop to help our patients with bradycardia and beyond.

1.11. Are there other dual chamber leadless pacemakers on the market and how does the Aveir DR differ from these?

AVEIR DR is currently the world’s only dual chamber leadless pacemaker system.

1.12. Could you also expand a little on the implant-to-implant technology that has been developed for the dual chamber expansion?

Abbott’s i2i™ (implant-to-implant) technology utilises high-frequency pulses to relay messages via the naturally conductive characteristics of the body’s blood between the two leadless pacemakers. To support the dual chamber therapy, each implant communicates beat-to-beat with a paired, co-implanted device. The delivery of these high-frequency pulses of data is coordinated with each locally paced or sensed event without impact on pacing or intrinsic sensing.

1.13. Has the device received any other approvals globally e.g. EMA?

Currently, the AVEIR DR dual chamber leadless pacemaker system is only approved in the U.S. It is currently under review for CE marking.

Declaration of interest

The author was supported by Abbott Medical. The author has no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.

Disclaimer

The opinions expressed in this interview are those of the interviewee and do not necessarily reflect the views of Taylor & Francis.

Additional information

Funding

This paper was not funded.