Fragments of Holter monitoring of a 64-year-old patient with paroxysms of supraventricular tachycardia are presented, atrial ectopic activity during tachycardia is recorded, which does not interrupt the tachycardia, but changes the sequence of RR intervals. The possibility of remote analysis of the data of 3-day monitoring of the patient’s electrocardiogram in 12-channel is provided.