An 84-year-old man comes to the emergency department due to a week-long history of dizziness, lightheadedness, and shortness of breath. His symptoms occur at any time but are worse with exertion. He has had no chest pain, palpitations, or syncope. Medical history includes hypertension, hypercholesterolemia, and benign prostatic hyperplasia. His medications are aspirin, lisinopril, atorvastatin, and tamsulosin.
Temperature is 36.7 C (98 F), blood pressure is 120/60 mm Hg, pulse is 36/min, and respirations are 16/min. On examination, the patient appears in no acute distress and has no symptoms. Other than a slow pulse rate, physical examination shows no abnormalities.
Initial laboratory studies, including complete metabolic panel, thyroid function tests, and cardiac markers, are within normal limits.
ECG is shown in the exhibit.
A transthoracic echocardiogram shows normal right and left ventricular size and function with an ejection fraction of 60%, along with mild mitral and tricuspid regurgitation.
Which of the following is the best next step in management of this patient?

Question

An 84-year-old man comes to the emergency department due to a week-long history of dizziness, lightheadedness, and shortness of breath.  His symptoms occur at any time but are worse with exertion.  He has had no chest pain, palpitations, or syncope.  Medical history includes hypertension, hypercholesterolemia, and benign prostatic hyperplasia.  His medications are aspirin, lisinopril, atorvastatin, and tamsulosin.
Temperature is 36.7 C (98 F), blood pressure is 120/60 mm Hg, pulse is 36/min, and respirations are 16/min.  On examination, the patient appears in no acute distress and has no symptoms.  Other than a slow pulse rate, physical examination shows no abnormalities.
Initial laboratory studies, including complete metabolic panel, thyroid function tests, and cardiac markers, are within normal limits.
ECG is shown in the exhibit. 
A transthoracic echocardiogram shows normal right and left ventricular size and function with an ejection fraction of 60%, along with mild mitral and tricuspid regurgitation.
Which of the following is the best next step in management of this patient?

Quizplus · Accepted Answer

This patient has symptomatic bradycardia with ECG showing every other P wave blocked (ie, nonconducted), consistent with 2:1 second-degree atrioventricular (AV) block. Ischemia, electrolyte abnormalities, medications (eg, beta blockers, nondihydropyridine calcium channel blockers), infiltrative disease (eg, sarcoidosis), or age-related fibrosis can lead to impaired electrical conduction across the AV node. Symptomatic second-degree AV block (eg, shortness of breath, lightheadedness, syncope) in the absence of a reversible cause (eg, pharmacologic AV nodal blockade, myocardial ischemia) is an indication for permanent pacemaker placement. ECG showing AV conduction at a 2:1 ratio represents a special scenario because it does not allow for the differentiation between Mobitz type I and Mobitz type II second-degree AV block. Such a distinction is important in asymptomatic patients because Mobitz type II AV block carries a high rate of progression to third-degree AV block and necessitates permanent pacemaker placement, whereas Mobitz type I AV block typically requires no intervention. Symptomatic second-degree AV block necessitates pacemaker placement regardless of whether Mobitz type I or Mobitz type II AV block is present. second-degree AV block (Choice A) This patient's clinical presentation and ECG are diagnostic of symptomatic second-degree AV block. Although he should be closely monitored for hemodynamic instability until a pacemaker is placed, further diagnostic testing will not change the need for a permanent pacemaker. (Choices B and E) Per advanced cardiac life support protocol, hemodynamically unstable patients (eg, those with hypotension, confusion, or chest pain) with bradycardia should be treated with intravenous atropine (0.5 mg every 3-5 minutes) or transcutaneous cardiac pacing. However, atropine can sometimes worsen bradycardia due to second-degree AV block and is not recommended in stable patients such as this one. Transcutaneous pacing is also not currently indicated in this stable patient. (Choice C) Dobutamine can be used for patients with refractory heart failure associated with AV block, but it is not currently indicated in this patient. Educational objective: Mobitz type I and Mobitz type II second-degree atrioventricular (AV) block cannot be differentiated when 2:1 atrioventricular block is present on ECG. Symptomatic second-degree AV block in the absence of a reversible cause necessitates placement of a permanent pacemaker regardless of whether Mobitz type I or Mobitz type II AV block is present. __________ References: Indications and recommendations for pacemaker therapy. (http://www.ncbi.nlm.nih.gov/pubmed/15864898)

An 84-Year-Old Man Comes to the Emergency Department Due to a Week-Long