Slide 1: 60M w/ symptomatic HF (EF 35%) who has been on guideline-directed medical therapy comes to your office with this EKG… [EKG]

Slide 2: …and this CXR.

Slide 3: [EKG shows left bundle branch block and wide QRS (160ms)] [CXR shows single lead ICD] What’s the next step in management?

Slide 4: Upgrade to cardiac resynchronization therapy (CRT)! *AKA “bi-ventricular pacing.” ACC/AHA Class I Indications for CRT: EF<35%, LBBB w/ QRS>150ms, symptomatic on GDMT. [CXR shows RA lead, LV lead (physically in the coronary sinus), RV lead]

Slide 5: After the upgrade… [EKG]

Slide 6: Now a RBBB Pattern (V1 with RSR’). [EKG shows RA lead pacemaker spike, LV lead pacemaker spike (The LV lead fires before the RV lead, resulting in an RBBB pattern), and RV lead pacemaker spike.


  • Epstein AE, DiMarco JP, Ellenbogen KA, et al. 2012 ACCF/AHA/HRS focused update incorporated into the ACCF/AHA/HRS 2008 guidelines for device-based therapy of cardiac rhythm abnormalities: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines and the Heart Rhythm Society. J Am Coll Cardiol. 2013 Jan 22;61(3):e6-75. doi: 10.1016/j.jacc.2012.11.007. Epub 2012 Dec 19. PMID 23265327

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