The updated NICE clinical guideline CG180 (2014) was published in June 2014. It gives guidance on the management of atrial fibrillation and recommends an ECG should be performed on all patients where atrial fibrillation is suspected where an irregular pulse has been detected, whether symptomatic or not.
It recommends using ambulatory ECG recording in patients with suspected paroxysmal AF as follows:
- A 24-hour Holter ECG monitor should be used in those with suspected asymptomatic episodes or symptomatic episodes less than 24 hours apart.
- An event recorder ECG should be used in those with symptomatic episodes more than 24 hours apart.
The National Service Framework for Coronary Heart Disease chapter on cardiac arrhythmias lists three quality requirements relating to patient support, diagnosis and treatment and sudden cardiac death.
So why aren’t more GPs using Event Recorders in Primary Care?
There are two main types of ECG recorders worn by patients in an ambulatory setting away from the
Surgery. They are Holter ECG recorders like the Meditech CardioMera or Event Capture ECG recorders like the Meditech CardioBlue and DCBiomed InstantCheck.
They are generally used to investigate suspected symptoms of arrhythmia including palpitations, light-headedness or syncope (partial or complete loss of consciousness), which have not been detected during a shorter 12 lead, surgery based ECG.
Holter or event recorder
Continuous full disclosure Holter ECG monitors were first used in the 1970s and typically operate for 24-48 hours recording every single heartbeat during this period.
This can mean that upwards of 100,000 beats are recorded over a 24 hour period. They are especially useful if the wearer does not feel or is not aware of the ECG abnormality, and are typically more expensive than event recorders.
In most cases data is now stored digitally either on internal flash memory or on removable SD data cards.
Data is uploaded to a computer where software automatically analyses the recording classifying it by beat type, identifying and labelling specific arrhythmias and in some cases, providing a textual summary for the clinician.
Reports should be customisable and have the ability to be attached to the patient’s clinical notes electronically.
Most Holter analysis software can run on a desktop PC and a separate dedicated PC is not required. This makes the analysis of the recording much quicker.
Event ECG recorders are different and are designed for patients who experience symptoms very infrequently and require monitoring over several days or even weeks.
This type of recorder is usually patient activated by pushing a button, but some can be programmed to record automatically at pre-set intervals or will trigger automatically at the onset of certain arrhythmias.
Some event recorders record post event data only. Others operate in a ‘loop’ memory mode so the device records 30 seconds of pre event and 30 seconds post event data. This is useful should the patient lose consciousness and allows the clinician to view the ECG immediately leading up to the event.
Traditionally, post event recorders would have had an external lead with electrodes fitted to the patient’s chest or be held against the chest to record. Recent advances in technology have seen the development of new recorders, which have built in finger or wrist watch type electrodes, which permit long term monitoring without the discomfort or irritation of a patient lead.