What determines where the doctor places an implantable cardioverter defibrillator?

Left side: The left side is preferable for several reasons - especially if you have a bi ventricular or crt icd - the one with 3 leads. It is easier to place the leads from the left side & the icd & leads are pass thru the heart for efib/shocking currents.

I Agree, and...: I agree with dr. Wright's answer. In addition, there is always a (very) small risk of nerve or vessel damage to the arm on the same side as the device, and it's best if it's not the dominant hand. Since most people are right-handed, it's quite convenient that the left side is the easiest and most effective location for us to place the device.