A 66-year-old man presents to the emergency department with shortness of breath. He typically has poor exercise tolerance and is only able to walk from his house to his mailbox before becoming dyspneic. He now has shortness of breath even at rest. He had a cold recently but has no new medical problems. His past medical history is notable for a myocardial infarction 7 years ago, COPD, heart failure with a left ventricular ejection fraction of 22%, obesity, diabetes, and peripheral vascular disease. His temperature is 97.7°F (36.5°C), blood pressure is 124/82 mmHg, pulse is 140/min, respirations are 32/min, and oxygen saturation is 78% on room air. Physical exam reveals an uncomfortable man with increased work of breathing. He demonstrates bilateral crackles and wheezing on pulmonary exam. The patient is started on BiPAP, and his oxygen saturation improves to 94%. An ECG is performed, as seen in Figure A, and a chest radiograph is performed, as seen in Figure B. Which of the following is the most appropriate next step in management?
Digoxin
Albuterol and prednisone
Intubation
Metoprolol
Digoxin
This patient with a history of heart failure with reduced ejection fraction is presenting with respiratory distress (increased work of breathing, hypoxia, wheezes, and crackles) in the setting of atrial fibrillation (ECG with irregularly irregular rhythm without P waves) with rapid ventricular response and pulmonary edema on chest radiograph. Digoxin is an appropriate medication that can both control the heart rate in atrial fibrillation and increase cardiac contractility and potentially improve respiratory symptoms in this decompensated patient with heart failure.

Atrial fibrillation presents on ECG with an irregularly irregular rhythm without discernible P waves. The initial management of atrial fibrillation with rapid ventricular response is rate control. If the patient is stable, possible first-line agents include beta-blockers (e.g., metoprolol) or calcium channel blockers (e.g., diltiazem). These agents may reduce cardiac contractility and worsen complications such as pulmonary edema in the setting of heart failure with reduced ejection fraction when the patient is in a decompensated state. If the patient has a reduced ejection fraction and requires rate control, then digoxin is a highly effective medication that blocks the AV node and increases cardiac contractility. Any hemodynamically unstable patient with atrial fibrillation with rapid ventricular response should immediately be cardioverted.

Moskowitz et. al review the management of atrial fibrillation. They note that in the management of atrial fibrillation with rapid ventricular response, metoprolol is commonly used in the intensive care setting, is more successful than amiodarone, and had better rate control when compared to diltiazem.

Ehle et. al note that digoxin is approved to control ventricular response in patients with chronic atrial fibrillation and is the only oral agent with positive inotropic effects approved for the management of mild to moderate heart failure.

Figure/Illustration A is an ECG demonstrating an irregularly irregular rate/rhythm (note the spacing of the blue arrows indicating the QRS complexes) without P waves, which is suggestive of atrial fibrillation. Figure B is a chest radiograph demonstrating bilateral, hazy interstitial infiltrates, which are concerning for pulmonary edema.

Incorrect Answers:
Answer A: Albuterol and prednisone would be appropriate management of a COPD flare, which presents in a patient with a history of smoking with dyspnea, wheezing, increased work of breathing, and a barrel chest. While this patient’s wheezing may be secondary to his COPD, it is much more likely to be a cardiac wheeze given his chest radiograph findings including pulmonary edema. Treating his atrial fibrillation is more likely to alleviate his pulmonary symptoms. Other treatments in COPD include ipratropium and BiPAP.

Answer C: Diltiazem would be an appropriate rate control agent for atrial fibrillation with rapid ventricular response, particularly in the setting of a COPD flare as it will not impair the mechanism of albuterol (which should be given as a nebulizer in COPD flares). In this patient, further impairing cardiac contractility with a calcium channel blocker may worsen his underlying pulmonary edema (given his reduced ejection fraction).

Answer D: Intubation would be indicated if this patient’s respiratory status were worsening, including failure to oxygenate, failure to ventilate, or impending respiratory failure. This patient’s respiratory status has improved on BiPAP; thus intubation is not needed.

Answer E: Metoprolol, like diltiazem, would reduce cardiac contractility and may worsen pulmonary edema, in particular, in a patient with a reduced ejection fraction. It also may cause COPD symptoms to emerge, as beta-2 blockade may cause bronchoconstriction (even though metoprolol is beta-1 selective). It would be indicated as outpatient rate control for a patient with atrial fibrillation who can tolerate a beta-blocker, and is preferred in patients with a history of acute coronary syndrome, as it reduces mortality.

Bullet Summary:
Patients with atrial fibrillation with rapid ventricular response with a reduced ejection fraction may be optimally managed with digoxin, which blocks the AV node and increases cardiac contractility.