Have a few that I use at various times.
For a primary text I've so far liked Josephson's Clinical Cardiac Electrophysiology and occasionally stuff from Braunwald's clinical arrhythmias and EP
In the beginning I used EP Testing by Fogoros as sort of a basic overview of a few topics.
I also have a couple of those visual case type guides by Drs Klein/Purves/Leong-Sit