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Improving AF Detection: The Evolving Role of Technology in Stroke Prevention

Helen Williams, FRPharmS, FFRPS

Atrial fibrillation (AF) is a major risk factor for stroke; however, up to 40% of patients with AF are asymptomatic. The first evidence of asymptomatic AF can be devastating, because stroke is the first symptom in ~25% of patients. This highlights the need for strategies to facilitate earlier diagnosis to allow the initiation of anticoagulation therapy to help reduce the risk of AF-related stroke. AF screening is effective and non-invasive, and once diagnosed, treatment is available to reduce the risk of stroke. The SAFE study was the largest randomized study of AF screening in primary care and demonstrated that screening is an effective way to increase detection rates compared with routine practice. The study also indicated that the levels of new detection rates for AF were similar whether screening was delivered opportunistically or systematically (1.64% versus 1.62%, respectively). Opportunistic AF screening has been recommended by European Society of Cardiology (ESC) and European Heart Rhythm Association (EHRA) publications in 2016 and 2017, respectively, particularly in patients considered to be at high risk and those aged ≥65 years.

 

Figure 1. Prevalence of AF by gender and age.

diagram

A significant proportion of patients with AF aged 65 years and older are asymptomatic.

How can the latest technology improve the detection of AF?

Pulse palpation is the recommended first step of screening for the detection of AF. However, despite being a cheap, simple way to screen, pulse palpation has a low specificity for AF and can, therefore, result in a high number of false positive results for suspected AF. Over recent years, several new devices and applications have been developed as screening tools to help detect AF, based on either pulse irregularity or rhythm analysis. The latest European guidelines recommend the use of such devices as an alternative approach to pulse palpation, as part of AF screening programmes. However, if AF is indicated, any electrocardiogram (ECG) readings should be reviewed by a physician, or a new ECG, preferably a 12-lead ECG, should be performed to confirm the diagnosis.

 

Examples of tools for the detection of AF

Category

Example

 

Automated BP sphygmomanometers

WatchBP Home A

 

 

The WatchBP Home A device contains a built-in algorithm that analyses the irregularity of a pulse rate and applies a threshold to detect AF during BP measurements

>It is the only automated BP monitor with a built-in AF algorithm Sensitivity 95%; Specificity 90% NICE Medical Technologies recommend the WatchBP Home A for the opportunistic detection of AF during the diagnosis and monitoring of hypertension

Mobile ECG recorder and applications

Kardia 
(previously AliveCor)

 

 

Pocket-sized ECG technology used with a mobile device application AF is detected in patients with intermittent palpitations Sensitivity >85%; Specificity >90% Sensitive to sound – may not be suit able for use in noisy environments

Event ECG monitors

MyDiagnostick

 

Single-lead ECG device for use when patients experience symptoms of arrhythmia
The stick has metallic handles encompassing the electrodes; a built-in AF algorithm provides instant analysis on a computer via USB Sensitivity 94%; Specificity 93%

AF, atrial fibrillation; BP, blood pressure; ECG, electrocardiogram; NICE,
National Institute for Health and Care Excellence

 

A meta-analysis by Taggar et al. reviewed 21 studies on methods of screening for AF. The results showed that modified blood pressure monitors and non-12-lead ECG devices had the highest levels of accuracy for both sensitivity and specificity, compared with smartphone applications and pulse palpation. The study highlighted the potential for new technologies to increase the detection of patients with suspected AF.

 

The success and accuracy of any of these AF detection tools are highly dependent on the population selected, the healthcare professionals involved and the setting of the AF screening programme. Screening tools need to be user-friendly, with quick and accurate results, to be considered an effective intervention in primary care. The key advantages of these new devices include the potential for cost savings (e.g. if these new screening tools with greater accuracy reduce the need for 12-lead ECGs, or even replace 12-lead ECGs, in the future) and the convenience of instant results and portable use. However, the barriers include the limited availability of the devices in clinics as well as having the right software and IT settings available. Additional training for healthcare professionals or patients may also be required.

 

Many areas, including non-healthcare settings, are starting to utilize these new technologies in routine practice, as a result of the promising sensitivity and specificity results. However, because the incentives for investment in these alternative methods are limited, endorsement by international guidelines and further research on their cost-effectiveness is needed.

 

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Helen Williams, FRPharmS, FFRPS

Helen Williams is a Consultant Pharmacist specializing in cardiovascular disease. She holds positions as Clinical Director for AF at the Health Innovation Network and is a National Clinical Adviser for AF within the Academic Health Science Networks. In her role as Chair of the Local Cardiovascular Medicines Working Group, she has developed and supported the implementation of consensus evidence-based guidance for use across a population of 3.6 million. She has a keen interest in improving the care of patients with, or at risk of, cardiovascular disease. Her current focus is on the rollout out of mobile ECG devices to improve the detection of AF and on strategies to increase the uptake of anticoagulation in patients with AF.

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