In Searching for Atrial Fibrillation, ECG Length Does Matter

In Searching for Atrial Fibrillation, ECG Length Does Matter

Introduction

Atrial fibrillation (AF) is one of the most prevalent arrhythmias in European society and its occurrence is increasing among the elderly. Epidemiological studies show that its presence will only grow over time. Many resources have been engaged to improve detection and treatment and to optimize quality of life for affected patients, but it still remains one of the leading risk factors for heart insufficiency, stroke and lowered life expectancy in both men and women. A key role in this threatening scenario is played by ischemic stroke – a disease whose risk is five times higher with concomitant AF. Being one of the major causes of disability and morbidity in society, stroke consumes huge resources. This could be changed with improved screening methods and early pharmacological intervention.

As previously stated, atrial fibrillation is more common in the elderly. During aging, the atria start to change their structure. They gain more fat and fibrous tissue, causing conduction disturbances. Structural and functional changes impair contraction and lead to chronic inflammation and the formation of a thrombus, which brings the risk of ischemic stroke.

Detection

AF is often insidious and clinically silent. A Finnish study from 2016 showed that in 21.9% of cases stroke is the first manifestation of an AF. If lowering the risk of a stroke in AF is obtainable with oral anticoagulants, monitoring and detection of the disease should be crucial.

A run of at least 30 seconds of AF is considered diagnostically significant. It has to be documented during ECG recording according to the criterion of complete irregularity of QRS complexes with no P waves. However, this remains challenging, as AF tends to appear as paroxysmal arrhythmia, and even short episodes can lead to stroke. That is why the preferred way of recording ECG signals is gradually changing towards novel, prolonged methods of detection that favour raised sensitivity.

Development of Guidelines

Considering the development of European Society of Cardiology (ESC) guidelines regarding AF we can see more attention being driven towards detection and how it should be done. There is an shift being observed in favour of prolonged ECG. In 2006 ESC guidelines, there is hardly any information on how long monitoring should be, whereas in 2010 and 2012 it is stated that regardless of the clinical symptoms, after a stroke or transient ischemic attack (TIA), with suspicion of AF, Holter monitoring should be performed for up to 7 days. What is important is that 7-day monitoring can validate up to 70% of AF. Also, implantable devices and event recorders were classified as a valuable option.

Methods of prolonged ECG have found a special place in the screening of neurological patients that have overcome stroke or TIA. In 2015 Lancet Neurolology published data pooled from ten studies (more than 600 patients) which showed that more than we have more than 3 times better chances (10.5% vs 3%)  to diagnose post-stroke atrial fibrillation with 7-day monitoring (comparing to standard 24 h examination)

All these conclusions led to class-I recommendations that in all patients with symptoms or complications of AFs it is advised to consider additional ECG monitoring. After stroke or TIA, it may be beneficial to monitor for 5 days with intermittent ECG.

Change of Devices

Not only is duration of monitoring important, but also comfort and simplicity of use for the patient. With ongoing miniaturisation of equipment and technological progress, several different options for long screening for AF are getting more attention compared to standard 12-lead ECG or Holter. Their advantage is often long-lasting battery time, to provide almost non-stop recording and simplicity of use, which is important for patient-operated systems that are suited to cost-effective screening in the elderly. The results of these studies are promising, starting from: patient-operated electrocardiographic systems, adhesive chest patches, iPhone ECG or shirt-based systems. Also, ideas like an intermittent thumb ECG twice a day is a convenient tool, making screening in at-risk patients easier.

The Clinician’s Perspective

Evolution of guidelines and innovations in the field of ECG recordings and intelligent algorithms is meant to help physicians in their everyday practice and to be of benefit to the widest group of patients. And clinicians do confirm this trend. Dr Ulrich Ingold, a cardiologist from a hospital in Interlaken, Switzerland, says:

“The number of long-term ECG recordings has been increasing steadily over the past few years in our institution. One reason is that long-term ECGs are superior to conventional 24-hour recordings in patients with suspected atrial fibrillation.”

However the amount of data comes with more manual work per examination. It is not hard to imagine how overwhelming it can be to deal with multiple 7-day Holter recordings. This is where modern technology enters the stage: Dr Ingold sums it up, saying:

It used to be very time-consuming to analyse long-term recordings with our conventional Holter software. Using Cardiomatics, the interpretation is now fast and reliable.”

Conclusions

Over time, prolonged ECG monitoring of AF is attracting more interest. Convincing data show progress in the application of 72-or-more hours’ recording in detecting this malicious arrhythmia; however no consensus on how long monitoring should be performed has been established. It is also worth emphasising that prolonged recordings are more often achieved with novel portable or telemetric devices and with the additional help of intelligent algorithms. We still need further investigation of proposed methods of monitoring and extensive multi-centre trials to determine the optimal duration of rhythm analysis and its benefits.

  1. Jaakkola J, Mustonen P, Kiviniemi T, et al. Stroke as the First Manifestation of Atrial Fibrillation. PLoS One. 2016;11(12):e0168010.
  2. Sposato LA, Cipriano LE, Saposnik G. et al. Diagnosis of atrial fibrillation after stroke and transient ischaemic attack: a systematic review and meta-analysis. Lancet Neurol. 2015; 14(4): 377-387.

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