Insertable loop recorders offer “the best opportunity” to diagnose unexplained syncope and abnormal heart rhythms


Nick Linker, James Cook University Hospital, Middlesbrough, UK, Executive Committee member of the Arrhythmia Alliance-UK’s heart rhythm charity-and president elect of the British Heart Rhythm Society, recently implanted, for the first time in the UK, the smallest version of an insertable loop recorder. He spoke to Cardiac Rhythm News on the role and advantages of implantable loop recorders in the diagnosis of syncope and cardiac arrhythmias, the main features of this new device and its cost-effectiveness.

What is the role of implantable loop recorders in the diagnosis of cardiac arrhythmias?

Implantable loop recorders are used to record a person’s rhythm in a number of situations. The most common use of implantable loop recorders is in the diagnosis of syncope. If a patient is having infrequent episodes of syncope, then conventional ambulatory ECG recorders are not that helpful as they require the patient to either have electrodes attached to their chest, which may not be practical for a long period of time, or they require the patient to activate the recorder, which in a patient with no warning before their syncope, will also not be useful.

Implantable loop recorders can also be used to document asymptomatic arrhythmias, for example patients with nocturnal arrhythmias or patients with atrial fibrillation who may not be aware of the arrhythmia but are still at increased risk of thromboembolism.

What are the advantages of using implantable loop recorders in the diagnosis of unexplained syncope?

As loop recorders are implanted in the patient and record continuously for up to three years, they offer the best opportunity to record the patient’s rhythm at the time of their symptoms, particularly in patients with infrequent episodes. In patients with unexplained syncope, this is often the only way to correlate their symptoms with their rhythm. As such, the implantation of a loop recorder is strongly recommended in these patients both by the European Society of Cardiology in their syncope guideline and by the UK’s National Institute for Health and Care Excellence (NICE) in its transient loss of consciousness guideline.

You were the first physician to implant the latest CE-marked and FDA-approved loop recorder from Medtronic, Reveal Linq, in the UK; could you tell us what the main features of this device are?

From the patient’s perspective, this new insertable cardiac monitor is much smaller than existing loop recorders. The insertion procedure is quicker with less discomfort and a better cosmetic result. The system also features automatic wireless data transfer between Reveal Linq and the Medtronic Carelink monitor which is then transmitted to the patient’s cardiologist.

From the physician’s perspective, the device is easier to implant and the remote monitoring system ensures that information from the device is received quicker.

How does this device compare with others in the market?

Compared with current devices, the new device is 1/10 the size but retains the same battery longevity (up to three years) and has new detection algorithms to aid in rhythm discrimination. The remote monitoring system is now automatic so patients do not have to use an “activator” to freeze the ECG recording as with current devices and it is easier to install and use as it features 3G technology rather than requiring a telephone line.

Tell us about the procedure?

The procedure is much quicker than current device implantation as the device is so much smaller. A small incision (<1cm) is made with a purpose-built blade and an insertion tool is used to deliver the device, in a similar way to other implants eg. drug implants. The skin is then glued together (it can be sutured). The whole procedure takes about 10 minutes. Due to the simplification of the procedure, it is likely that it will not require a catheter laboratory or operating theatre to insert the device which could be undertaken for example in the out-patient clinic at the same time as a patient attends for their consultation, saving delay in diagnosis plus inconvenience for patients and freeing up space in the catheter laboratory.

Are there any risks associated with the implantation of the device?

Potential risks with the device are those associated with any implant and include local bruising/bleeding, infection and device migration. However, due to the small size of the device plus the simpler and shorter insertion procedure, these are likely to be considerably less than with current devices.

What about cost-effectiveness?

Implantable loop recorders have been demonstrated to be cost effective in the diagnosis of syncope (hence the NICE and ESC recommendations). Many patients with unexplained syncope undergo extensive tests (often unnecessary), have a number of referrals to different physicians eg. a neurologist, plus visits to the emergency department prior to having a loop recorder implanted. There is good evidence that implantable loop recorders have a high diagnostic yield in terms of either confirming an arrhythmia as the cause of symptoms or excluding it.

In terms of the new device, whilst the system (device/monitor, etc) is more expensive than other devices, this can be offset by the ease of implant freeing up capacity in the catheter laboratory and as the device can be implanted earlier, even at the patient’s first visit, this would cut down on unnecessary tests and referrals.

What data are available to support the safety and effectiveness of Reveal Linq?

Although data is limited as yet with such a new device [Medtronic announced CE mark, FDA approval and global launch of Reveal Linq on 19 February], initial experience has not shown any safety issues. All devices so far have been inserted without problems and with positive feedback from both patients and doctors.