If your palpitations are hard to catch, we try 24 hour monitors, and 1 week event recorders. If that fails, we might resort to an implantable loop recorder. That needs a hospital stay, and some discomfort, as the machine is the size of a USB stick. Now, I have seen the next generation. This is the size of a small bullet, and can but put in without sutures, and without X-rays.
You get your own Bluetooth monitor to download information, and it can be sent remotely to the doctor. This is a revolution in invasive assessment- it is almost (but not quite) NON-invasive!
http://www.medtronic.com/patients/fainting/device/our-insertable-cardiac-monitors/reveal-linq-icm/