Overall good agreement of smartphone-based and standard base-apex electrocardiography in healthy sheep.

Objective: To assess and compare the quality of smartphone ECG tracings to standard (base-apex) ECG tracings and assess agreement of ECG parameters between smartphone-based ECG and standard ECG.

Animals: 25 rams.

Procedures: The rams were consecutively examined with standard ECG and smartphone-based ECG (KardiaMobile; AliveCor Inc) after physical examination. ECGs were compared for quality score, heart rate, and ECG waves, complexes, and intervals. Quality scores were based on the presence or absence of baseline undulation and tremor artifacts using a 3-point scoring system (lowest possible = 0; highest possible = 3). A lower score was indicative of a better-quality ECG.

Results: Smartphone-based ECGs were interpretable in 65% of cases, while 100% of standard ECGs were interpretable. Standard ECG quality was superior to smartphone-based ECG quality, with no agreement in the quality between devices (κ coefficient, -0.0062). There was good agreement for heart rate with mean difference 2.86 beats/min (CI, -3.44 to 9.16) between the standard and smartphone ECGs. Good agreement was observed for P wave amplitude with mean difference 0.02 mV (CI, -0.01 to 0.05), QRS duration with mean difference -10.5 ms (CI, -20.96 to -0.04), QT interval with mean difference -27.14 ms (CI, -59.36 to 5.08), T wave duration with mean difference -30.00 ms (CI, -66.727 to 6.727), and T wave amplitude with mean difference -0.07 mV (CI, -0.22 to 0.08) between the 2 devices.

Clinical Relevance: Our findings indicate good agreement between standard and smartphone ECG for most parameters, although 35% of smartphone ECGs were uninterpretable.