A 66-year-old man with a history of chronic obstructive pulmonary disease (COPD) comes to the emergency department due to gradually worsening shortness of breath and wheezing for the past several days. The patient also has a productive cough with mucoid sputum but no fever or chest pain. His other medical problems include hypertension and hypercholesterolemia. The patient has a 35-pack-year smoking history and quit 5 years ago. Temperature is 37.1 C (98.8 F), blood pressure is 130/80 mm Hg, and pulse is 114/min and irregular. Pulse oximetry is 86% on room air. Physical examination reveals moderate respiratory distress, bilateral expiratory wheezing, and distant heart sounds. ECG shows an irregular narrow complex tachycardia with 3 different P-wave morphologies and a variable PR interval. Serum electrolytes are within normal limits. Which of the following is the best next step in management of this patient's cardiac arrhythmia?

Question

A 66-year-old man with a history of chronic obstructive pulmonary disease (COPD) comes to the emergency department due to gradually worsening shortness of breath and wheezing for the past several days.  The patient also has a productive cough with mucoid sputum but no fever or chest pain.  His other medical problems include hypertension and hypercholesterolemia.  The patient has a 35-pack-year smoking history and quit 5 years ago.  Temperature is 37.1 C (98.8 F), blood pressure is 130/80 mm Hg, and pulse is 114/min and irregular.  Pulse oximetry is 86% on room air.  Physical examination reveals moderate respiratory distress, bilateral expiratory wheezing, and distant heart sounds.  ECG shows an irregular narrow complex tachycardia with 3 different P-wave morphologies and a variable PR interval.  Serum electrolytes are within normal limits.  Which of the following is the best next step in management of this patient's cardiac arrhythmia?

Quizplus · Accepted Answer

11ec25c8_d4bd_1100_bc81_636976d354c0_MD0003_00 This patient's ECG findings are consistent with multifocal atrial tachycardia (MAT). MAT is a supraventricular tachyarrhythmia that likely occurs due to atrial conduction abnormalities triggered by disturbances such as right atrial enlargement, catecholamine surge (eg, sepsis), or electrolyte imbalance. It is most commonly seen in elderly (age >70) patients with an acute exacerbation of underlying pulmonary disease (eg, chronic obstructive pulmonary disease [COPD]). Patients typically have symptoms of the underlying disturbance (eg, cough, wheezing, shortness of breath), and the tachycardia itself is usually asymptomatic (other than possible palpitations). Cardiac examination in patients with MAT should reveal an irregular rhythm with rapid rate. The diagnosis is confirmed by ECG showing distinct P waves of >3 different morphologies, irregular RR intervals, and an atrial rate >100/min. The best treatment is appropriate management of the inciting disturbance; the administration of bronchodilators, systemic corticosteroids, and supplemental oxygen/ventilatory support for this patient's acute exacerbation of COPD can lead to resolution of the MAT. ECG (Choices A and E) MAT is often confused with atrial fibrillation. ECG in both MAT and atrial fibrillation shows irregular RR intervals; however, MAT demonstrates distinct P waves with varying morphology while P waves are absent in atrial fibrillation. Antiarrhythmic drugs (eg, amiodarone) or direct current cardioversion are often used in patients with atrial fibrillation but are not effective in converting MAT to sinus rhythm. atrial fibrillation (Choice B) Unlike atrial fibrillation, MAT does not create an increased risk of atrial thrombus formation and thromboembolism; therefore, anticoagulation is not recommended. (Choice D) Pharmacologic rate control with calcium channel blockers (eg, verapamil) or cardioselective beta blockers (eg, metoprolol) is indicated for MAT only when rapid ventricular rate leads to myocardial ischemia or congestive heart failure or when the arrhythmia persists despite management of the underlying disturbance. Beta blockers may worsen bronchospasm in patients with exacerbation of COPD and should be used with caution. Educational objective: Multifocal atrial tachycardia is a supraventricular tachyarrhythmia characterized by distinct P waves with >3 different morphologies, atrial rate >100/min, and an irregular rhythm. It is usually precipitated by acute respiratory illness in patients with underlying lung disease. Treatment should be directed at correcting the underlying inciting disturbance. > References: Multifocal atrial tachycardia. (http://www.ncbi.nlm.nih.gov/pubmed/9440591) 2015 ACC/AHA/HRS guideline for the management of adult patients with supraventricular tachycardia: a report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines and the Heart Rhythm Society. (http://www.ncbi.nlm.nih.gov/pubmed/26399663)

A 66-Year-Old Man with a History of Chronic Obstructive Pulmonary