Loss of Right Atrial Pacing Lead Capture Due to Myocardial Infarction Obscuring Diagnosis on Electrocardiogram

Right coronary artery occlusion can lead to failure to capture from the right atrial pacing lead. In this case, acute infarction resulted in failure of the right atrial lead to capture and thus increased right ventricular pacing. The new ventricular pacing masked the diagnosis of acute myocardial infarction. (Level of Difficulty: Intermediate.)