A woman with congenital pulmonary valve stenosis treated by balloon valvulotomy had been visiting the outpatient clinic for many years with complaints of palpitations. Several 24-h electrocardiogram (ECG) recordings and resting ECGs (Fig. 1a) showed frequent premature ventricular contractions and two regular wide-complex asymptomatic tachycardias of a maximum of eight beats with a maximal frequency of 120 beats/min. However, these findings could not be related to her complaints.

Fig. 1
figure 1

a Routine resting electrocardiogram (ECG) of the patient. b Recording of atrial fibrillation with intermittent bundle branch block by on-demand single-lead ECG in the mHealth program

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The patient was included in a novel mHealth telemonitoring program. While the patient was having palpitations, a single-lead ECG was recorded (Fig. 1b). On these additional recordings atrial fibrillation could be diagnosed with intermittent bundle branch block.

There is a broad aetiology of palpitations, and these often occur outside the window of 24-h Holter monitoring. This case is one of the first to illustrate that mHealth programs, including on-demand ECG monitoring, can be of great importance in the diagnosis of arrhythmias.