ASPIRED: Early ECG monitoring could accelerate diagnosis after unexplained syncope

Immediate 14-day ambulatory ECG monitoring did not significantly reduce recurrent syncope at 1 year in the ASPIRED trial, but it more than doubled the detection of clinically significant arrhythmias and enabled earlier diagnosis and treatment.

The ASPIRED trial, presented during a Hot Line session at ESC Congress 2026, investigated whether initiating prolonged ambulatory electrocardiographic (ECG) monitoring soon after an emergency department (ED) presentation for unexplained syncope could improve patient outcomes.

The multicenter, open-label randomized trial enrolled patients across 45 UK hospitals whose syncope remained unexplained following ED assessment. Participants were randomized to receive either 14 days of continuous ambulatory ECG monitoring or standard care.

The primary endpoint — the mean number of patient-reported episodes of syncope at 1 year — was not significantly different between the monitoring and standard-care groups (1.37 versus 1.58 episodes; incidence rate ratio, 0.89; 95% CI, 0.68–1.18). However, immediate monitoring more than doubled the detection of clinically significant cardiac arrhythmias, from 9% with standard care to 22%, and shortened the median time to diagnosis from 55 days to 22 days. Pacemaker implantation was also more frequent in the monitoring group (6.8% versus 4.6%), as was antiarrhythmic treatment (10.8% versus 7.3%).

An exploratory finding also showed lower all-cause mortality at 1 year in the monitoring group (1.5% versus 2.9%), although further research is needed to understand this observation.

Following the presentation, Prof. Matthew Reed, from the Usher Institute, University of Edinburgh, and the Emergency Medicine Research Group Edinburgh, spoke about the origins of ASPIRED, the importance of earlier investigation for patients with syncope, and how this approach might be incorporated into routine care.

What prompted you to investigate earlier ECG monitoring in patients presenting with unexplained syncope?

This trial was probably about 10 years in the making. The original concept came about because I work in the emergency department and we see a huge number of patients coming through with syncope.

Cardiologists perhaps see a very select group of those patients who ultimately get as far as a referral. If somebody has a very convincing story — for example, exercise-induced syncope, perhaps they are an athlete or there is some relevant family history — everybody has quite a low threshold for thinking this could have a cardiac cause, and they are seen by cardiology early.

But for many of our patients, if we are worried, some will be admitted and some will go home, and then they may wait what is supposed to be 6 weeks, but is probably months, before getting to a cardiology clinic. I felt that we should be offering those patients something better than we were doing at the time.

I was also involved in developing the 2018 ESC Guidelines for the diagnosis and management of syncope,² where I led on the emergency medicine aspect. A lot of that was about risk stratifying patients by putting them into high-, medium-, and low-risk groups. That was all very well, but we did not really have anything different to offer them as a result.

I was therefore looking for something we could actually do early on, rather than simply putting people into a risk group: something that might either reassure patients or identify the underlying cause earlier. I had previously done some work with patients presenting with palpitations, where people can record an ECG while they are conscious. The difficulty with syncope is that the patient is unconscious, so you need some type of device that is continuously recording.

At the time, there were devices available in the UK that could continuously record for 14 days. I thought we should potentially be offering that from the ED. There was also some evidence beginning to emerge that we might be more likely to pick up events if we recorded patients very soon after their episode. It also made sense to record for 14 days rather than 2 days with a traditional Holter monitor. We did some work around whether 7 days or 14 days would be enough, and from there the trial gradually came together.

Beyond detecting arrhythmias, could earlier monitoring improve the experience for patients with unexplained syncope?

Yes. I think one of the important things this approach can do is provide reassurance much earlier. From an emergency medicine perspective, we are particularly concerned about whether we might send somebody home who has a cardiac arrhythmia and who then goes on to have a bad outcome. But there are also many patients who have vasovagal syncope and recurrent episodes. Once we have decided that we do not think there is a cardiac cause, there is perhaps less that we can offer them within the emergency department.

With earlier monitoring, we may be able to rule out a cardiac cause, or at least make it much less likely, at a much earlier stage. We can then reassure somebody that although they are still fainting, we do not think it is due to a heart problem. That potentially removes one of the major sources of worry while they pursue other ways of managing their syncope.

The patient perspective was important when we designed the study. STARS and Arrhythmia Alliance were stakeholders in the trial, and Trudie Lobban was a member of the trial steering committee. Their input helped us think about what matters to patients and partly informed our choice of primary outcome, which focused on patients’ episodes of syncope rather than simply whether we detected an arrhythmia. STARS also has very good patient information resources, which we have incorporated into our local guidelines. There is still probably more that could be done for patients with recurrent benign syncope, but being able to investigate them earlier and provide reassurance about a cardiac cause is an important part of their care.

What would be the practical challenges of introducing this approach more widely into routine care?

This was a research study, so we had access to research infrastructure and research nurses who were dedicated to recruiting patients. We recruited some patients in the emergency department and some elsewhere within the hospital. Some patients were phoned the following day and had the device sent out to them, while others came back the next day to have it fitted.

The question now is how we would deliver that in routine clinical care. In a busy emergency department with large numbers of patients, I do not think it is deliverable within the 4–8 hours that the patient is with us. We therefore need a model for delivering it. I think that could be through a same-day emergency care setting or an ambulatory care clinic,³ where patients either go directly or return to have the device fitted.

Another possibility would be a rapid-access syncope clinic. We have those services available, although our waiting time is currently around 2 weeks, which is probably too long for this approach. But those services may be able to accommodate this type of pathway. The infrastructure is potentially already there; we need to work out how best to use it.

What is the main potential clinical impact of the ASPIRED findings?

I think this trial offers an opportunity for patients who currently have unexplained syncope. They may be unable to drive and can wait a long time for follow-up. This gives them access to an investigation very early on, immediately after the trauma of coming to an emergency department following a syncopal episode. It gives them something early that investigates what the cause might be. It can provide reassurance, but it can also identify patients who have worrying findings much earlier and allow earlier treatment, potentially giving them a better outcome.

There is obviously a signal in the study that we may be able to provide people with better outcomes, and that can only be a good thing. The question now is how we incorporate this into existing NHS care.

References

1. Reed MJ, Goodacre S, Weir CJ, et al. Immediate Ambulatory Electrocardiographic Monitoring in Syncope. N Engl J Med. 2026; Published online August 31. doi:10.1056/NEJMoa2605812.
2. Brignole M, Moya A, de Lange FJ, et al. ESC Scientific Document Group. 2018 ESC Guidelines for the diagnosis and management of syncope. Eur Heart J. 2018;39:1883–1948. doi:10.1093/eurheartj/ehy037.
3. Cullen J, Reed MJ, Muir A et al. Experience of a smartphone ambulatory ECG clinic for emergency department patients with palpitation. Eur J Emerg Med. 2021; 28: 463-468. doi: 10.1097/MEJ.0000000000000859