Screening of older patients for atrial fibrillation in general practice: Current evidence and its implications for future practice

Figures & data

Table 1. A selection of devices suitable for opportunistic screening for AF in the primary care setting.

Device and manufacturer	Description	Validation and diagnostic accuracy data	Recommended for use in the primary care setting?	Cost-effectiveness data available?	Convenience of use
WatchBP Microlife	BP cuff Automated BP monitor with inbuilt AF detection system.	– Six trials (n = 2332) using BP cuffs with the AF detection algorithm by Microlife [42] resulted in sensitivity and specificity values of 90–100%. – Unselected primary care population (= 1000, mean age 79.7 years) [24]: sensitivity: 94.9%, specificity: 89.7%.	Yes: NICE recommendation [43].	Yes: small cost-saving compared with pulse palpation [43].	Can be used at home; requires correct positioning of the cuff; patient must return device for data download.
MyDiagnostick Applied Biomedical Systems	Handheld ‘bar’ device one-lead ECG device	– Primary care population of patients with known paroxysmal or chronic AF (n = 161) and a convenience sample of individuals without AF (n = 30) [45]: sensitivity: 94%, specificity: 93% – Primary care influenza vaccination clinics, n = 676 patients attending a single clinic: diagnostic accuracy of 100% for patients with known AF and detection of AF in a further 11 patients not previously diagnosed [44]. – Across 10 Dutch primary care practices: 37 (1.1% of all those screened) new cases of AF detected [22].	No	Yes: lifetime costs and effects of a single screening session for AF detection in a community setting [23].	Can be used at home; patient must return device for data download.
Zenicor-ECG Zenicor Medical Systems	Handheld unit one-lead ECG device with two thumb sensors	– Evaluated in 22 patients diagnosed with symptomatic, paroxysmal AF, with patients asked to make two recordings per day for 30 days and additional recordings if arrhythmia symptoms arose [46]. Patients also underwent 24-h ambulatory monitoring. – Diagnosis of AF events: Intermittent monitoring: 18 patients (82%); 24-h monitoring: seven patients (32%; p = 0.001).	No	Cost-effectiveness of two weeks of intermittent screening for asymptomatic AF in 75/76-year-old individuals [26].	Recordings can be collected remotely via a server to facilitate clinical review.
AliveCor AliveCor Inc.	Sensors attached to smartphone or smartwatch.	– Among a validation set of 204 patients that included 48 with confirmed AF [47]: sensitivity: 98%, specificity: 97%, diagnostic accuracy: 97%. – Evaluated in 381 individuals including healthy young adults (n = 128), elite athletes (n = 123) and patients attending a cardiology clinic (n = 130) [48]: sensitivity in ambulatory cardiology patients: 94.4%, specificity: 100% in healthy young adults, 99.2% in elite athletes and 99.1% in ambulatory cardiology patients.	No	Cost-effectiveness of community screening increased with improved anticoagulant therapy adherence [21].	Recordings can be collected remotely via a server to facilitate clinical review.
Cardiio Rhythm Cardiio, Inc.	PPG smartphone app	– Evaluated in 1013 ambulatory patients from a general outpatient clinic aged ≥65 with hypertension and/or diabetes [37]: sensitivity: 92.9%, specificity: 97.7%.	No	No data available.	Can be used at home (positive results require verification by ECG).

BP: blood pressure.

Box 1. Automated blood pressure monitors for AF screening.

Several blood pressure monitors have been adapted using an embedded algorithm that detects pulse irregularities indicative of AF with a sensitivity and specificity between 90% and 100% using ECG diagnosis as a reference [42]. By contrast, sensitivity and specificity for pulse palpitation have been measured at 87.2% and 81.3%, respectively [20]. On the basis of these studies, NICE recommended the WatchBP^TM device (Microlife AF, Widnau, Switzerland; Table 1) for opportunistic screening of AF among individuals with suspected hypertension and those undergoing screening or monitoring for hypertension in the primary care setting [43]. The NICE evaluation identified a small estimated cost saving of £2.98 per person screened in those aged 65–74 years rising to £4.26 for those aged ≥75 years, compared with pulse palpation and subsequent referral for ECG, based on the costs of each modality and anticipated cost savings associated with stroke prevention [43]. In a separate study of 1000 elderly patients (mean age 79.7 years; range: 75.1–99.8 years) recruited from six general practices in the UK, the WatchBP device outperformed two single-lead ECG devices (Omron HCG-801 and Merlin ECG event recorder), achieving a sensitivity of 94.9% and a specificity of 89.7% for the detection of AF (95% confidence interval 87.5–91.6%) [24].

Box 2. Single-lead ECG devices for AF screening.

Handheld, single-lead ECG devices are an attractive option for AF screening because the resulting ECG can be analysed by a physician in the case of a positive result, eliminating the need for a follow-up ECG [44]. Such devices include: the MyDiagnostick (Applied Biomedical Systems BV, Maastricht, The Netherlands), a ‘bar’ device that generates a one-minute ECG when held by the user; the Zenicor-ECG (Zenicor Medical Systems AB, Stockholm, Sweden), a device that records a 30-s ECG when thumbs are placed on the sensors; and the AliveCor (AliveCor, Inc., San Francisco, USA), which consists of two sensors that attach to the back of a smartphone and an App that captures a 30-s ECG when the user’s fingers are placed on the electrodes. These devices and the results of associated validation studies, including sensitivity and specificity, are described in further detail in Table 1.

Box 3. Pulse photoplethysmographic (PPG) devices for AF screening.

Another approach to AF monitoring by smartphone is an App that uses the light source and camera of the phone to obtain a PPG recording of the pulse wave, then applies an algorithm to analyse its regularity. A recent study evaluated the ‘Cardiio Rhythm’ App (in development) (Table 1) and AliveCor device (Box 2) in ambulatory patients aged ≥65 years with hypertension and/or diabetes from a general outpatient clinic [37,38]. The results indicated a sensitivity of 92.9% and specificity of 97.7% for the app, compared with 71.4% and 99.4%, respectively, for the AliveCor device [38].

Table 2. World Health Organization: principles of early disease detection [36].

Principles
The condition sought should be an important health problem.
There should be an accepted treatment for patients with recognized disease.
Facilities for diagnosis and treatment should be available.
There should be a recognizable latent or early symptomatic stage.
There should be a suitable test or examination.
The test should be acceptable to the population.
The natural history of the condition, including development from latent to declared disease, should be adequately understood.
There should be an agreed policy on whom to treat as patients.
The cost of case-finding (including diagnosis and treatment of patients diagnosed) should be economically balanced in relation to possible expenditure on medical care as a whole.
Case-finding should be a continuing process and not a ‘once and for all’ project.

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