Successful coronary sinus reducer implantation in a patient with a pre-existing left ventricular pacing lead: a case report.

Background: Coronary sinus reducer (CSR) implantation offers symptomatic relief in patients with refractory angina who remain symptomatic despite optimal medical therapy and repeated revascularization procedures. Pre-existing coronary sinus pacing leads can complicate device delivery and raise concerns about lead displacement or venous injury. Case summary: A 77-year-old man with ischaemic heart failure (left ventricular ejection fraction 33%), a cardiac resynchronization therapy defibrillator (CRT-D; upgraded from a previously implanted implantable cardioverter-defibrillator), and Canadian Cardiovascular Society Class III refractory angina after extensive revascularization was evaluated for alternative treatment. Despite multiple interventions addressing recurrent in-stent restenoses, disabling angina persisted, prompting referral for CSR implantation. Right internal jugular venous access was selected for favourable coronary sinus alignment, with ultrasound guidance and use of an extrastiff guidewire and selective venography to delineate anatomy. Advancement of the 12 Fr delivery sheath was impeded by a prominent Thebesian valve; a 5 mm balloon was inflated at the obstruction and then partially inflated to facilitate 'balloon-assisted tracking,' enabling safe sheath passage without injuring the venous wall or disturbing the left ventricular lead. The CSR was deployed in the mid-distal coronary sinus with stable pacing parameters and no immediate procedural complications. During follow-up the patient remained free of angina. Discussion: This case demonstrates technical feasibility and safety of CSR implantation in the setting of a pre-existing left ventricular pacing lead and challenging venous anatomy when meticulous access selection, balloon-assisted tracking, angiographic confirmation, and systematic monitoring of lead electrical parameters are employed.