difference between wavelet filters
Comparative Analysis of Wavelet Basis Functions for ECG Signal Compression through Compressive Sensing, 2012 provides a comparative analysis for different wavelets. On a more generic basis, Compressed Sensing for Bioelectric Signals: A Review, 2015, addresses other kinds on splines, Gabor wavelets, etc. The references therein could provide you with a good starting point. 

Fixed percentage of wavelet coefficients to be zeroed for ECG ccompression, 2003, could be interesting as well, but I cannot access the paper.