ST-elevation myocardial infarction in the presence of biventricular paced rhythm

In the diagnosis of acute myocardial infarction (AMI), the presence of baseline left bundle branch block or a permanent pacemaker rhythm poses a challenge.

We present a case report highlighting this challenge, along with a review of pertinent literature.

A 70-year-old female with known severe idiopathic dilated cardiomyopathy and moderate coronary artery disease who was status post-biventricular pacemaker/implantable cardioverter defibrillator insertion was brought to our institution via Emergency Medical Services with recurrent firing of her implantable cardioverter defibrillator and syncope. After stabilization in the Emergency Department and treatment with intravenous amiodarone, the patient admitted to having ongoing chest pains. The electrocardiogram revealed evidence of biventricular pacing with superimposed ST-segment elevations in the anterolateral leads indicative of myocardial injury. She underwent prompt angiography, thrombectomy, and bare-metal stent insertion to a totally occluded proximal left anterior descending coronary artery, with resolution of her chest pain and improvement in the ST-segment changes.

Despite proposed criteria that aid in the recognition of AMI with underlying left bundle branch block and paced rhythm; the advent of new pacing modalities and the potential variability of pacing sites impose additional diagnostic challenges requiring higher level of suspicion and better physician awareness.