Background: Electrocardiograms (ECGs) recorded with the help of wearable devices and additional smartphone apps play an increasingly important role in cardiological diagnostics.

Case Summary: We present two cases in whom an ECG was recorded during cardiac-related symptoms using the patients' smartphones. Previous standard resting and 24-hour ECGs had revealed no pathologies. In the first case, a 67-year-old female patient reported paroxysmal palpitations at least once a month lasting about 3-20 minutes. Repeated emergency department visits had revealed no relevant findings. Ambulatory 24-hour-ECG and echocardiography revealed no relevant abnormalities. The patient was equipped with a smart phone based 12-lead ECG system and was able to document the tachycardia after one week (figure A). Subsequently, AV nodal reentry tachycardia could be diagnosed and treated with a Slow Pathway Modulation.
In the second case, a 30-year-old female patient reported recurrent exertional and resting angina pectoris. The symptoms had aggravated during the last months and occurred several times per day. Comprehensive cardiac diagnostics including ECG, echocardiography and cardiac MRI had revealed no relevant abnormalities. The patient was equipped with a smart phone based 12-lead ECG system and successfully recorded the ECG during a chest pain attack where ischemic changes were seen (figure B). Suspecting a coronary vasomotion disorder, an acetylcholine (ACh) spasm provocation test was performed. The ACh test revealed coronary microvascular spasm (figure C) and appropriate medical therapy was initiated.
Discussion: Wearable, smartphone-based ECG systems, which can be used by the patient independently while experiencing cardiac-related symptoms, are a modern diagnostic tool. Considering the use of these systems is beneficial for early diagnosis and appropriate treatment for paroxysmal arrhythmias and ischemic ECG changes as seen in coronary vasomotion disorders.