A 33-year-old man comes to the emergency department with a 2-day history of generalized weakness, lightheadedness, palpitations, and poor energy. Four weeks ago, he noticed an annular rash on his right thigh that lasted for a couple of days and then faded. He has no fever, weight loss, chest pain, or headache. He lives on Long Island, New York, and jogs 7 miles 3 times a week.
Which of the following is the most likely cardiac finding in this patient?

Question

A 33-year-old man comes to the emergency department with a 2-day history of generalized weakness, lightheadedness, palpitations, and poor energy.  Four weeks ago, he noticed an annular rash on his right thigh that lasted for a couple of days and then faded.  He has no fever, weight loss, chest pain, or headache.  He lives on Long Island, New York, and jogs 7 miles 3 times a week.
Which of the following is the most likely cardiac finding in this patient?

Quizplus · Accepted Answer

11ec193a_9645_6336_853d_ddca7e019f8d_MD0002_00 This patient is from a Lyme disease-endemic area and had a transient thigh rash 4 weeks earlier, suggesting Lyme disease caused by Borrelia burgdorferi. Patients typically present with initial erythema migrans and nonspecific flu-like symptoms (eg, fever, fatigue, headache, and body aches). As the disease disseminates in the following weeks to months, patients may present with acute neurologic and/or cardiac symptoms as the first clinical sign of the disease. Lyme carditis, as in this patient, may be asymptomatic or present with palpitations (most common), lightheadedness, syncope, dyspnea, or chest pain. Palpitations can be a nonspecific finding and may not represent true underlying heart disease. Lyme carditis most commonly presents (objectively) with atrioventricular (AV) conduction blocks that sometimes fluctuate between first- and second-degree block. Progression to complete heart block is possible, and the risk is increased with PR interval > 300 msec. Lyme myopericarditis is usually self-limited and sometimes causes mild pericardial effusion but rarely causes cardiomegaly (Choices C and D). Although cardiomyopathy has been reported in Europe, there have been no such cases reported in the United States. Atrial and ventricular tachyarrhythmias occur less commonly in Lyme carditis (Choices A and E). Diagnosis is confirmed by clinical features and positive ELISA and western blot Lyme serologies. Current guidelines recommend hospital admission with IV antibiotics (ceftriaxone preferred) to prevent long-term complications in symptomatic patients and those with second- or third-degree AV block or first-degree AV block with PR interval > 300 msec. Oral antibiotics (eg, doxycycline, amoxicillin, and cefuroxime) should be continued at discharge for a 21- to 28-day total course. Complete AV block requires temporary pacing as these blocks are self-limited and usually improve within 1 week. Lesser conduction disturbances may take up to 6 weeks for resolution. Educational objective: Lyme carditis can be asymptomatic or present with palpitations, lightheadedness, syncope, dyspnea, or chest pain. Atrioventricular conduction block is the most common cardiac presentation and can progress to complete heart block. Hospital admission with IV antibiotics (ceftriaxone preferred) is recommended for symptomatic patients and those with second- or third-degree AV block or first-degree AV block with PR interval > 300 msec. __________ References: Lyme disease and the heart. (http://www.ncbi.nlm.nih.gov/pubmed/12957829)

A 33-Year-Old Man Comes to the Emergency Department with a 2-Day