Validation of a smartphone-based event recorder for arrhythmia detection.

INTRODUCTION: Ambulatory cardiac monitoring devices such as external loop recorders (ELRs) are often used in the outpatient clinic to evaluate palpitations. However, ELRs can be bulky and uncomfortable to use, especially in public, at work, or in social situations. An alternative approach is a smartphone-based electrocardiographic (ECG) recorder/event recorder (Kardia Mobile [KM]), but the comparative diagnostic yield of each approach has not been studied.

METHODS: Thirty-three patients with palpitations wore an ELR and carried a KM for a period of 14-30 days. They were instructed to transmit ECGs via KM and also to activate the ELR whenever they had symptoms. The tracings obtained from both devices were independently analyzed by two cardiologists, and the overall arrhythmia yield, as well as patient preference and compliance, were evaluated. The paired binomial data obtained from both devices were compared using an unconditional test of noninferiority.

RESULTS: Of the 38 patients enrolled in the study, more patients had a potential diagnosis for their symptoms (i.e., at least one symptomatic recording during the entire monitoring period) with KM than with the ELR (KM = 34 [89.5%] vs ELR = 26 [68.4%]; χ2  = 5.1, P = 0.024). In the per protocol analysis, all 33 patients (100%) had a potential diagnosis using the KM device, which was significantly higher compared to 24 patients (72.2%) using the ELR (χ2  = 10.4, P = 0.001).

CONCLUSIONS: KM is noninferior to an ELR for detecting arrhythmias in the outpatient setting. The ease of use and portability of this device make it an attractive option for the detection of symptomatic arrhythmias.