A case report: SPEAR-CRT: first description of use of left bundle branch area pacing tools and techniques to place an endocardial LV lead via the interventricular septum in a patient with ostial coronary sinus occlusion.

Background: Cardiac resynchronization therapy (CRT) is a well-established treatment with heart failure (HF) and conduction delays. Complex anatomy, such as coronary sinus (CS) stenosis can render LV lead placement challenging or impossible. Alternate strategies such as epicardial and left bundle branch area pacing (LBBAP) exist, though have their own disadvantages. Case summary: A 72-year-old male with a history of ischaemic cardiomyopathy, LV dysfunction, and pacemaker dependence presented to hospital in decompensated HF after two failed attempts to upgrade to a CRT system, the latest including a sub-optimal LBBAP lead. The patient was brought back to the EP lab for a third attempt to engage the CS. Despite several different techniques, these attempts failed. With the patients consent, we proceeded to an off-label bailout strategy by placing an LV endocardial lead using LBBAP tools. When combined with pacing simultaneously through the previously positioned LBBAP, lead this gave an improved QRS morphology on the surface ECG. In follow-up, the patient's functional class and left ventricular ejection fraction improved, while maintaining 98.3% biventricular pacing. Discussion: We present a complex patient who ultimately benefited from the novel use of LBBAP equipment to place an endocardial LV lead via the interventricular septum in the setting of several prior failed attempts at placing a traditional LV lead through a stenosed CS. No further options remained for this patient, with palliation as the only alternative. Endocardial LV lead placement should be studied as in future trials as an alternative to traditional transvenous and epicardial CRT systems prior to widespread adoption.