Utility and accuracy of a smartphone-based electrocardiogram device as compared to a standard base-apex electrocardiogram in the horse

Abstract

Objective: Evaluate accuracy and utility of a smartphone-based ECG device compared to a standard base-apex lead ECG in horses.

Methods: ECGs were acquired prospectively from 28 client-owned horses at 2 equine referral hospitals. Twenty-five pairs of 30-s ECG recordings were acquired simultaneously from 23 horses with a smartphone ECG device (a bi-polar single lead recorder coupled to a smartphone with an ECG application) and with a standard base-apex lead ECG; 2 horses provided two pairs of simultaneously acquired ECGs. In one horse, the ECGs pairs were recorded immediately sequentially. An additional 7 smartphone ECGs were recorded from 5 horses without contemporaneous reference ECGs. Three observers independently evaluated all ECGs without knowledge of ECG pairing. Inter- and intra-observer agreement between the 2 ECG modalities was evaluated for rhythm diagnosis and QRS polarity. Heart rate agreement was also evaluated.

Results: Intra-observer agreement for rhythm assessment was very high; one observer diagnosed the same cardiac rhythm on both recordings in 24/26 instances and two observers agreed in 25/26 instances. The polarity of the QRS complex was similar on ECGs acquired simultaneously by both systems. Heart rates calculated from ECG pairs were within 1 beat of each other.

Conclusions: The smartphone-acquired ECG accurately identified cardiac rhythm and heart rate in most horses. In one case, small size of the complexes precluded identification of P waves on smartphone-acquired ECGs, resulting in a misdiagnosis. The smartphone-acquired ECG device might allow veterinarians to evaluate and monitor cardiac arrhythmias relatively inexpensively in field or hospital settings.

Keywords: Electrocardiogram; Equine; Heart rate; Rhythm; Smartphone.