Isoprenaline induced myocardial infarction in a patient with high-grade atrioventricular block: a case report

Background: Isoprenaline is widely used in the treatment of symptomatic bradycardia. Myocardial infarction precipitated by the therapeutic use of isoprenaline has not been reported in the literature. Case summary: We describe the case of a 67-year-old male patient who presented to our institution with symptomatic Mobitz type II 2:1 atrioventricular block. He had a several-month history of unexplained syncope. He had several cardiovascular risk factors but did not have a diagnosis of coronary artery disease. On admission, he was symptomatic with dizziness but had no chest pain. High-sensitivity troponin I was normal. After initiation of an isoprenaline infusion, he developed cardiac-sounding chest pain and an ischaemic electrocardiogram. Emergency coronary angiography was performed that demonstrated a severe mid-vessel stenosis in his right coronary artery that was treated with percutaneous coronary intervention and the deployment of one drug-eluting stent. He remained in Mobitz type II 2:1 atrioventricular block 48 hours after the procedure, and a dual-chamber permanent pacemaker was implanted. He was discharged in a stable condition with no further chest pain or bradyarrhythmia. Discussion: To our knowledge, this is the first reported case of myocardial infarction precipitated by the therapeutic use of isoprenaline. Our hypothesis is that isoprenaline increased myocardial oxygen demand and induced a type 2 myocardial infarction in this patient with occult coronary artery disease. Isoprenaline should be used with caution in patients with confirmed or suspected coronary artery disease.