Successful management of complete heart block in checkpoint inhibitor induced myocarditis by left bundle branch area pacing: a case report.

Background: Optimal management of checkpoint inhibitor-induced complete heart block is unknown. Previous reports showed relatively high incidence of pacing failure due to the co-existing myocarditis. Case summary: A 71-year-old male with a prior history of stage IV metastatic squamous cell lung cancer presents was admitted for dyspnoea and hypotension 10 days after checkpoint inhibitor treatment using pembrolizumab. He was found to have myocarditis, third-degree AV block, severe left ventricular systolic dysfunction with EF 35%, and required pressure support. A dual chamber pacemaker using left bundle branch area pacing (LBBAP) was urgently placed that immediately improved his haemodynamics. Both the cathode and anode were able to capture the ventricle at different pacing outputs. The patient was taken off all intravenous pressors and successfully transferred to a larger centre for further management of the myocarditis with no further arrhythmia or hypotension. Discussion: In conclusion, because of the unique ability to capture a large amount of myocardium from both the tip and ring electrodes as well as the ability to deliver cardiac resynchronization therapy, LBBAP may be the preferred pacing strategy in patients who develop complete heart block due to checkpoint inhibitor-induced myocarditis.