Some current trends of the use of non-linear time-frequency filtering approach to ECG signal processing are discussed herein. A brief review of an application potentiality of non-linear filtration is offered for long-term ECG signal processing. Possible problems of long-term monitoring, related to measurements interference and noise of ECG signal, are revealed. To eliminate the revealed problems, in further research, an implementation of a processing system using the non-linear-threshold time-frequency filtering method is planned. It is expected to improve an accuracy of cardiac data processing considering features of interference and measurement noise of different intensity.