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

In cardiology, CRT stands for cardiac resynchronization therapy. CRT is used in heart failure with reduced ejection fraction. According to the Universal Definition and Classification of Heart Failure, heart failure with reduced ejection fraction has left ventricular ejection fraction of 40% or less. CRT is a type of pacemaker in which three chambers of the heart are paced, right atrium, right ventricle and left ventricle.

[@Drsallyhamoly]

Thank you Professor . But why there are 2 shocking coils, in CRT-D?

[@JohnsonFrancisMBBSMDDM]

That is for programming different shock vectors in case one is not effective. Earlier even a subcutaneous array used to be installed in addition. (Purely subcutaneous ICD and extravascular ICD have extracardiac shocking coils - subcutaneous in the former and substernal in the latter).