Validation of a Novel Smartphone-based Photoplethysmographic Method for Ambulatory Heart Rhythm Diagnostics - the SMARTBEATS study.

BACKGROUND AND AIMS: In the current guidelines, smartphone-photoplethysmography (PPG) is not recommended for diagnosis of atrial fibrillation (AF), without a confirmatory electrocardiogram (ECG) recording. Previous validation studies have been performed under supervision in healthcare settings, with limited generalizability of the results. We aim to investigate the diagnostic performance of a smartphone-PPG method in a real-world setting, with ambulatory unsupervised smartphone-PPG recordings, compared with simultaneous ECG recordings and including patients with atrial flutter (AFL).

METHODS: Unselected patients undergoing direct current cardioversion for treatment of AF or AFL were asked to perform one-minute heart rhythm recordings post-treatment, at least twice daily for 30 days at home, using an iPhone 7 smartphone running the CORAI Heart Monitor PPG application simultaneously with a single-lead ECG recording (KardiaMobile). PPG and ECG recordings were read independently by two experienced readers.

RESULTS: In total, 280 patients recorded 18,005 simultaneous PPG and ECG recordings. Sufficient quality for diagnosis was seen in 96.9% (PPG) vs 95.1% (ECG) of the recordings (p < 0.001). Manual reading of the PPG recordings, compared to manually interpreted ECG recordings, had a sensitivity, specificity, and overall accuracy of 97.7%, 99.4% and 98.9% with AFL recordings included, and 99.0%, 99.7% and 99.5% respectively with AFL recordings excluded.

CONCLUSION: A novel smartphone-PPG method can be used by patients unsupervised at home to achieve accurate heart rhythm diagnostics of AF and AFL with very high sensitivity and specificity. This smartphone-PPG device can be used as an independent heart rhythm diagnostic device following cardioversion, without requirement of confirmation with ECG.