A 65-year-old man presents to the emergency department with anxiety and intermittent palpitations. He began feeling the palpitations 3 days ago while eating dinner. He denies chest pain, shortness of breath, or loss of consciousness. He has a history of hypertension, major depressive disorder, Raynaud disease, and chronic obstructive pulmonary disease (COPD) on 2 liters of oxygen at home. Current medications include lisinopril, inhaled umeclidinium-vilanterol, and as-needed albuterol. He drinks 4 beers a day and has smoked 1 pack of cigarettes a day for 40 years. His temperature is 98.9° F (37.2° C), blood pressure is 130/85 mmHg, pulse is 125/min, and respirations are 16/min. Physical exam is notable for an irregular pulse and scattered end-expiratory wheezes. An echocardiogram performed 1 month ago showed a left ventricular ejection fraction of 60-65%. The patient requires 3 liters of oxygen today. An ECG is performed as seen in Figure A. Which of the following is the most appropriate treatment for the patient’s tachycardia?
Amiodarone
Digoxin
Verapamil
Metoprolol
Verapamil
This patient’s new-onset palpitations, irregularly irregular pulse, and absent p-waves on ECG are consistent with atrial fibrillation. In hemodynamically stable patients with a relative contraindication to β-blockers (COPD on home oxygen with increasing oxygen need), rate control with a non-dihydropyridine calcium channel blocker such as verapamil is preferred.

Atrial fibrillation can present with palpitations, lightheadedness, or shortness of breath. ECG findings will be an irregularly irregular rhythm and absent P waves with an erratic baseline as shown in Illustration A. Treatment is centered on rate control. First-line agents for rate control include β1 selective blockers (metoprolol and esmolol) and non-dihydropyridine calcium channel blockers (verapamil and diltiazem). In patients with COPD, non-selective β-blockers (propranolol, timolol, and sotalol) can worsen bronchoconstriction by activating β2-adrenoreceptors. Other relative contraindications to β-blockers include Raynaud disease and depression (increased risk of fatigue and sexual dysfunction). In patients with relative contraindications to β-blockers, non-dihydropyridine calcium channel blockers are the preferred initial treatment option.

Van Gelder et al. studied lenient (resting heart rate < 110 beats per minute) versus strict rate control (resting heart rate < 80 beats per minute) in patients with atrial fibrillation in a randomized control trial. The authors found that there was no difference in the primary composite outcome of death from cardiovascular causes, hospitalization for heart failure, stroke, bleeding, and life-threatening arrhythmias between the 2 groups. The authors recommend a lenient rate control strategy in patients with atrial fibrillation.

Figure/Illustration A is an ECG lacking P waves (red arrows) and irregularly irregular RR intervals (red/blue lines), which are classic findings in atrial fibrillation.

Incorrect Answers:
Answer A: Amiodarone is an antiarrhythmic that can be used in patients to convert atrial fibrillation to sinus rhythm. It is often suitable to use in patients with depressed left ventricular function. Amiodarone has multiple multi-system adverse effects including pulmonary toxicity, and it is not used as a first-line agent.

Answer B: Clopidogrel is an antiplatelet agent that can be used to reduce the risk of thrombosis. Although patients with atrial fibrillation are at increased risk of stroke, the preferred anticoagulation agents are warfarin or direct oral anticoagulants (apixaban).

Answer C: Digoxin can be used as a rate control agent in atrial fibrillation as it directly suppresses atrioventricular nodal conduction. Due to its narrow therapeutic window and risk of toxicity, it is used as second-line therapy when first-line agents fail.

Answer D: Metoprolol is a β-blocker that is a first-line agent for rate control in atrial fibrillation. In patients with contraindications to β-blockers, non-dihydropyridine calcium channel blockers are the treatment of choice. This patient has COPD with increasing oxygen needs making calcium channel blockers possibly a better choice.

Bullet Summary:
In hemodynamically stable patients with atrial fibrillation and relative contraindications to β-blockers, non-dihydropyridine calcium channel blockers are the treatment of choice.