A validation study of a smartphone application for heart rate variability assessment in asymptomatic adults.

Background: Assessment of heart rate variability (HRV) is an effective non-invasive tool to obtain data on cardiac autonomic modulation and may be assessed by a range of devices, including mobile applications. This study aimed to validate a smartphone application by comparing the R-R intervals (RRi) obtained by the app with a classic electrocardiogram (ECG)-derived reference condition Methods: Fifteen asymptomatic adults (24.9±3.4 years) underwent an orthostatic challenge during which RRi were simultaneously recorded by a freeware smartphone application and by an ECG recorder. Pearson correlation coefficients () and coefficients of determination ( ) were calculated to determine the degree of association between the two electronic devices. Two-way repeated measures analysis of variance and Bland-Altman analysis were used to calculate the measurement consistency and agreement, respectively, between the two methods. Effect size was also used to estimate the magnitude of the differences.

Results: The number of RRi from asymptomatic adults recorded by the ECG and by the free smartphone application was similar at rest in supine position (13,149 vs. 13,157; = 0.432) and during orthostatic challenge (10,666 vs. 10,664 ). RRi in milliseconds from both devices presented a near perfect correlation in the supine position ( = 0.999; Confidence Interval [CI] at 95%: 0.999-0.999; P < 0.0001) and during orthostatic challenge (r = 0.988; 95% CI: 0.988-0.989; P < 0.0001). A negative bias of -0.526 milliseconds (95% limits of agreement [LoA] from -4.319 to 3.266 milliseconds) was observed in supine position between ECG and the smartphone application. On the other hand, a positive bias of 0.077 milliseconds (95% LoA from -10.090 to 10.240 milliseconds) during the orthostatic challenge was observed.

Conclusions: Our results cross-validated a freeware smartphone application with the ECG-derived reference condition for asymptomatic adults at rest in the supine position and during orthostatic challenge.