Third-degree atrioventricular block induced by escitalopram and quetiapine in a patient with depression: a case report

Third-degree atrioventricular block (AVB) associated with the use of escitalopram and quetiapine is rare, with limited cases reported. We present a case of drug-induced third-degree AVB in an elderly patient undergoing treatment for depression. A 70-year-old woman with a history of depression was initially treated with milnacipran and alprazolam, but the regimen was altered due to insufficient therapeutic response. Two weeks after initiating escitalopram and quetiapine, she developed third-degree AVB. Electrocardiogram (ECG) revealed sinus rhythm with complete AV block, atrioventricular junctional escape rhythm, QT interval prolongation, and a heart rate of 45 bpm. Emergency pacemaker implantation was performed. This case highlights the potential for escitalopram and quetiapine to induce serious cardiac conduction abnormalities, particularly in elderly patients. Regular ECG monitoring is essential when prescribing these agents to minimize the risk of malignant arrhythmia.