Smartphone-derived multichannel electrocardiogram for exercise stress testing

The use of mobile devices for electrocardiogram (ECG) recording and the ability to use this technology to immediately review dynamic waveforms is growing tremendously. While over-the-counter ECG devices may display rhythm disorders and ST-segment changes at rest, changes during physical exercise have thus far not been evaluated. We compared a mobile device (smartphone/tablet)-enabled vectorial 4-electrode ECG system (SPE) with the current standard 12‑lead (STE) ECG both at rest and during exercise.

A total of 428 patients underwent simultaneous ECG testing with both technologies during rest and maximal exercise. The vectorial ECG was displayed as 12‑lead ECG, and diagnostic accuracy and ECG quality (independently judged by blinded cardiologists) were compared with the current standard. Signal quality was good with both ECG technologies. At rest, there was excellent agreement between SPE and STE regarding rhythm (98%), AV-conduction (97%), wave duration (90%), and electrical axis (88-97%). During exercise the presence or absence of ST-deviation (>0.1 mm) corresponded in 90% of cases with no statistically significant difference. The positive predictive value was 48.5% and the negative predictive value was 94%. For ST-deviations >0.2 mm the percentage match was 97% during exercise. For rhythm disorders and for intraventricular conduction (left- and right-bundle branch block detection) it was >90%.

A smart-device-enabled vectorial ECGs system using the CardioSecur system can be used in daily practice to reliably interpret an ECG at rest and during physical exercise, although it is less accurate with respect to the detection of ST-deviation.