Loop recorders and the 24-hour tape: there has to be a better way! The IPED study

Why was the study needed? What knowledge gap was it trying to address?

Palpitations are a common presenting complaint to the Emergency Department (ED) but the symptoms have commonly settled at the point of presentation and initial investigations are often normal. Outpatient investigation is usually with ECG monitoring but short-term monitoring often fails to coincide with the patient’s symptoms and longer-term monitoring can be expensive. Over the last few years, several new ambulatory ECG monitoring devices have been developed and although these have been assessed for use in specific conditions, they haven’t been tested in a more general, acute medical population.

What question were the researchers trying to answer?

The IPED trial aimed to assess the use of a smartphone-based ECG event recorder versus standard care, to see which would better detect rhythms associated with palpitations or pre-syncope.

How did they answer their research question?

The IPED study was a prospective, multi-centre randomised control trial. It was conducted in 10 hospitals across England and Scotland from 2016 to 2018. Patients were included if they were over 16 years and attended with palpitations or pre-syncope with no obvious cause and an undiagnostic ECG. They were randomised to receive either standard care (according to local hospital policy) or standard care plus a smartphone-based event recorder. The primary outcome was the rate of detection of a ‘symptomatic rhythm’ (i.e. an ECG recording at the time of symptoms) at 90 days.

What were the main findings from the research?

The study analysed data from 240 patients. The mean age of participants was 40 years and 91% of participants presented with palpitations.

The rate of symptomatic rhythm detection was 9.5% in the control group (usual care) versus 56% in those who used the smartphone-based event recorder. This difference was statistically significant (p < 0.001) with a relative risk of 5.9 (95% confidence interval 3.3 – 10.5). It should be noted though that this includes detection of any rhythm associated with symptoms, including benign rhythms such as sinus rhythm, sinus tachycardia and ectopic beats.

The authors did look at the rate of detection of cardiac arrhythmias as a secondary outcome. They found the rate of detection was significantly higher in the group using the smartphone-based device (8.9% versus 0.9% in the control group, p = 0.006), although the overall numbers in this group are incredibly small (11 and 1 in the intervention and control groups respectively) so this result needs to be interpreted with caution.

Another important finding, particularly from the patient’s perspective, was the time taken to detect any symptomatic rhythm. The mean time was 9.5 days in the smart-phone group compared to 43 days with usual care (p < 0.001).

Are there any limitations we should be aware of?

The study used one particular make of smartphone-based event recorder. Whether other variations of this technology would perform similarly would need to be established.

The way that follow up was run in the study is also worth considering: the ECG recordings were transmitted to a central team who analysed the rhythm. In the case of benign rhythms, they wrote to the patient and their GP, whereas for cardiac arrhythmias, they alerted the local study team who arranged further urgent assessment. This arrangement may not be feasible in some systems, so clinicians who are considering bringing smartphone technology into their local protocols need to consider how follow-up would be integrated into their current pathways.

What is the take home message from this paper, will it change how we practice?

The number of cardiac arrhythmia’s detected in the study was low and this should be reassuring to us as clinicians.

The IPED study showed that the use of a smartphone-based ECG event recorder was safe and was more likely to capture a symptomatic ECG rhythm than traditional outpatient monitoring. There are many different models that could be used to introduce this technology into our practice. For example, the team behind IPED have now introduced a smartphone palpitation service in their ambulatory medicine clinic – patients are brought back the day after their ED attendance, are fitted with the device and are then followed up at one month.