How do you identify the subset of heart failure patients who are likely to benefit from cardiac resynchronization therapy in the setting of an RBBB pattern?

There are no good criteria to delineate which patients with RBBB will benefit from traditional CRT. The best contemporary strategy is to consider CRT if a patient has an RBBB > 150 ms, an atypical morphology (suggesting an underlying delay in the LBBB or an IVCD), and Class III-IV HF symptoms. One might also consider pacing in the setting of a prolonged 1st degree AV block in an effort to improve HF symptoms. Whether conduction system pacing will show more benefit than CRT via the CS is the subj...