A 23-year-old man comes to the clinic for a physical examination prior to joining a professional soccer team. The patient goes on a 10-mile run 3 or 4 times per week, during which he experiences no chest pain, lightheadedness, or shortness of breath. Medical history is unremarkable. He does not smoke or drink alcohol. The patient lives in Texas and has not traveled recently. Family history includes myocardial infarction in his father at age 56. Blood pressure is 114/62 mm Hg and pulse is 54/min. Cardiac examination reveals normal heart sounds with no murmurs. The lungs are clear to auscultation. ECG shows sinus bradycardia with occasional dropped QRS complexes preceded by progressive lengthening of the PR interval. No ST-segment abnormalities are present, and the QTc interval is normal. Which of the following is the most appropriate next step in the management of this patient?

Question

A 23-year-old man comes to the clinic for a physical examination prior to joining a professional soccer team.  The patient goes on a 10-mile run 3 or 4 times per week, during which he experiences no chest pain, lightheadedness, or shortness of breath.  Medical history is unremarkable.  He does not smoke or drink alcohol.  The patient lives in Texas and has not traveled recently.  Family history includes myocardial infarction in his father at age 56.  Blood pressure is 114/62 mm Hg and pulse is 54/min.  Cardiac examination reveals normal heart sounds with no murmurs.  The lungs are clear to auscultation.  ECG shows sinus bradycardia with occasional dropped QRS complexes preceded by progressive lengthening of the PR interval.  No ST-segment abnormalities are present, and the QTc interval is normal.  Which of the following is the most appropriate next step in the management of this patient?

Quizplus · Accepted Answer

11ec25c8_d0ad_7c4d_bc81_53dbf4c687e8_MD0003_00 This patient's ECG shows progressive lengthening of the PR interval followed by a dropped QRS complex, consistent with Mobitz type I second-degree atrioventricular (AV) block. Highly trained endurance athletes typically have very high resting vagal tone, making sinus bradycardia and low-grade AV block (ie, first degree and Mobitz type I second degree) common findings on resting ECG. These are benign findings and require no intervention. (Choice A) Exercise stress testing is used to evaluate for obstructive atherosclerotic coronary artery disease (CAD). AV nodal ischemia can lead to AV block, but there is no suspicion for significant CAD in this young patient who experiences no symptoms (eg, chest pain, shortness of breath) at high levels of exertion. (Choice B) Varying degrees of AV block can occur in a small percentage of patients with Lyme disease who do not receive antibiotic treatment. However, transmission of Lyme disease is uncommon in Texas (it is usually transmitted in the northeastern and upper Midwestern parts of the United States), and low-grade AV block is an expected finding in this highly trained endurance athlete. United States (Choice C) Permanent pacemaker placement is indicated for advanced AV block, including Mobitz type II second-degree AV block (ie, randomly dropped QRS complexes) and third-degree AV block (ie, complete dissociation of P waves and QRS complexes). (Choice E) The presence of a systolic ejection murmur can suggest aortic stenosis or hypertrophic cardiomyopathy, which would warrant transthoracic echocardiography for further investigation. However, echocardiography is not indicated in this asymptomatic patient with no cardiac murmurs. Educational objective: Low-grade atrioventricular block, including first degree and Mobitz type I second degree, are common findings on resting ECG in highly trained endurance athletes because of their high levels of resting vagal tone. These findings are benign and require no intervention. References: ECG variants and cardiac arrhythmias in athletes: clinical relevance and prognostic importance. (http://www.ncbi.nlm.nih.gov/pubmed/2191578)

A 23-Year-Old Man Comes to the Clinic for a Physical