What is the difference between CRT-P and CRT-D?

In cardiology, CRT stands for cardiac resynchronization therapy. CRT is used in heart failure with reduced ejection fraction. CRT is a type of pacemaker in which electrical leads are placed in three chambers of the heart, right atrium, and the left ventricle. CRT-D has an additional implantable cardioverter defibrillator incorporated within the device.