Validation of a new smartphone application (“FibriCheck”) for the diagnosis of atrial fibrillation in primary care

Oral Presentation Cardiostim

June 18th 2017

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 Background

Atrial fibrillation (AF) is highly prevalent among the elderly. Stroke prevention guidelines recommend opportunistic screening for heart rhythm irregularities in people aged 65 and older. A novel smartphone application, FibriCheck was recently introduced as an alternative screening method. This app uses the technique of photoplethysmography (PPG) to detect AF. This study was designed to investigate the diagnostic accuracy of the FibriCheck app for the detection of AF.

Methods

A phase II diagnostic accuracy study in a convenience sample of 242 subjects recruited in primary care. The majority of the participants were patients with a known history of AF (n = 160). A PPG measurement was obtained while patients held their index finger on the smartphone camera during one minute. A synchronized single-lead ECG was taken on the chest. Both traces were interpreted by the FibriCheck AF algorithm. First, the results of the FibriCheck algorithm were compared with 12-lead electrocardiographic recordings. Secondly, beat-to- beat comparison was done between the PPG and the single-lead ECG measurements.

Results

The signal quality filter of the application defined 29 PPG’s and 10 single-lead traces as poor and unreliable signal quality. For the PPG measurement and interpretation by the FibriCheck app, a sensitivity of 98% (95% CI 92 - 100), a specificity of 88% (95% CI 80 - 94) and an accuracy of 93% (95% CI 89 - 96) were obtained. False positive results were caused by atrial (n = 7) or ventricular (n = 1) extrasystoles and by failure of the quality filter of the application in recognizing a poor and unreliable signal (n = 4). For the single-lead ECG interpretation by the FibriCheck app, a sensitivity of 98% (95% CI 93 - 100), a specificity of 90% (95% CI 83 - 95) and an accuracy of 94% (95% CI 91 - 97) was found. The 11 false positive results were due to atrial (n = 10) and ventricular (n = 1) extrasystoles. Beat-to-beat analysis of the synchronized PPG and single-lead ECG traces showed a small difference in performance (99% uniform diagnoses), due to the different measurement method.

Conclusion

The FibriCheck is an accessible standalone smartphone application that showed promising results for AF detection in a primary care convenience sample. The app scored a high accuracy and sensitivity and a moderate to high specificity. The PPG measurement method nearly matched single-lead ECG performance. These findings make the app a possible candidate to implement in future screening or case-finding programs for AF.

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