Initial diagnosis/assessment:
He was found to be in third-degree Atrioventricular (AV) block and was sent to our emergency department. A repeat electrocardiogram (EKG) confirmed the diagnosis of third-degree AV block with junctional escape (Figure 1). The patient was a very healthy young man in the past with no previous EKG. His vital signs included normal blood pressure and oxygen saturation with a HR of 30-40 beats per minute. His complete heart block did not respond to atropine administration in the emergency department. Further testing including a chest x-ray, echocardiogram, complete metabolic panel, complete blood count (CBC), and a thyroid-stimulating hormone, (TSH) were all within normal limits. Due to his stable condition, he was discharged. His 30 days Holter monitor showed persistent third-degree AV block. He underwent treadmill stress testing using the Bruce protocol on which he exercised for 12 minutes attaining a peak heart rate of 44 beats per minute with persistent third-degree AV block. (figure 2) His Lyme titer was negative. His magnetic resonance imaging (MRI) testing of his heart was completely normal without any late gadolinium enhancement. After few months of observation, his third-degree AV block persisted leading to a permanent dual chamber pacemaker insertion.