A 72-year-old man comes to the emergency department due to progressive shortness of breath and cough productive of yellowish sputum. The patient says, "I have been feeling breathless for the past several months while mowing the lawn or walking around the house, but it has been worse over the last 3 days." He has had no chest pain or leg swelling but notes that his heart "has been racing." The patient has a history of hypertension, peptic ulcer disease, and osteoarthritis. He was hospitalized for pneumonia a year ago and required intravenous antibiotics. Six months ago, the patient underwent a cardiac stress test for chest discomfort, which was unremarkable. The patient has smoked a pack of cigarettes daily for 45 years. Blood pressure is 160/90 mm Hg, pulse is 148/min, and respirations are 26/min. He is speaking in partial sentences and using accessory muscles of respiration but is alert and cooperative. There is no jugular venous distension or heart murmurs, rub, or gallops, but the heart sounds are irregular. Lung auscultation reveals bilateral rhonchi and expiratory wheezes. Arterial blood gases while breathing 2 L of oxygen via nasal cannula reveal PO₂ of 66 mm Hg, PCO₂ of 52 mm Hg, and pH 7.33. ECG shows narrow QRS complexes with distinct P waves of different morphologies and variable PR segments and R-R intervals. Chest x-ray reveals no pulmonary infiltrates or consolidation. Inhaled bronchodilators and systemic glucocorticoids are administered.
Which of the following is the most appropriate additional step in management of this patient's arrhythmia?

Question

Quizplus · Accepted Answer

Explanation: 11ec2b69_be3a_ae8d_8f63_1d62d1ef5c8b_MD0005_00 This patient's ECG findings are consistent with multifocal atrial tachycardia (MAT). MAT may result from atrial conduction abnormalities triggered by disturbances such as right atrial enlargement, catecholamine surge (eg, sepsis), or electrolyte imbalance. MAT is most commonly seen in elderly patients (eg, age >70) with an acute exacerbation of underlying pulmonary disease (eg, chronic obstructive pulmonary disease [COPD]). Patients typically present with symptoms of the underlying illness (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 at least 3 different morphologies, irregular R-R intervals, and an atrial rate >100/min; the elevated atrial rate differentiates MAT from a diagnosis of wandering atrial pacemaker. The best treatment is appropriate management of the inciting illness; the administration of bronchodilators, systemic corticosteroids, and noninvasive ventilation (indicated due to respiratory distress with use of accessory muscles) for this patient's probable exacerbation of undiagnosed COPD can lead to resolution of the MAT. ECG (Choice A) Intravenous amiodarone is used for pharmacological cardioversion in patients with atrial fibrillation; however, it is not used in management of MAT. (Choices B and C) Intravenous nondihydropyridine calcium channel blockers (eg, verapamil, diltiazem) and beta blockers (eg, esmolol) can be used to control the rapid ventricular rate in patients with MAT. However, these medications do not address the underlying cause of MAT, and treatment of the inciting illness is the best initial management. (Choice E) Urgent synchronized cardioversion is appropriate for hemodynamically unstable supraventricular tachycardia; however, MAT rarely leads to hemodynamic instability. Management of the underlying COPD exacerbation is most appropriate in this patient with adequate blood pressure and organ perfusion. Educational objective: Multifocal atrial tachycardia most commonly occurs in elderly patients who are hospitalized with an exacerbation of underlying pulmonary disease (eg, chronic obstructive pulmonary disease). The diagnosis is made by ECG demonstrating P waves of at least 3 different morphologies and an atrial rate >100/min. Treatment involves appropriate management of the underlying inciting illness. 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 72-Year-Old Man Comes to the Emergency Department Due to Progressive