PO-01-044 THEOPHYLLINE FOR TREATMENT OF PAINFUL LEFT BUNDLE BRANCH BLOCK

Painful left bundle branch block (LBBB) is characterized by chest pain in setting of transient LBBB, the absence ischemia. Management has focused on pharmacological suppression sinus rate to prevent or invasive therapy with permanent pacing. To determine feasibility using oral theophylline for treatment painful LBBB. N/A A 71-year-old man presented evaluation exertional left-sided that resolved rest. 12-lead electrocardiogram (ECG) showed bradycardia at 54 bpm. Transthoracic echocardiogram was normal and coronary angiography non-obstructive artery disease. Symptoms persisted despite microvascular angina beta-blockers ranolazine. Heart ECG monitoring an Apple watch demonstrated reproducible symptoms when heart increased above 80 bpm resolution decrease below this threshold. Electrophysiology study rate-related concurrent onset atrial pacing a cycle length 550 ms (∼109 bpm) (Panel A) prompt narrowing QRS lower rates. Transient right intentionally induced catheter manipulation B) produced 1:1 conduction down up 113 no then 2:1 His C). Isoproterenol infusion allowed 127 without evidence LBBB D). The patient discharged 100 mg bid, which similar chronotropic dromotropic effect as isoproterenol. He reported significant improvement functional status recurrence symptomatic We report first case successful theophylline. mechanism may be damaged fibers bundle. Theophylline should considered patients whom node been unsuccessful management pacemaker not desired.