Review Question - QID 221300

This patient who presents with new-onset palpitations and absent p-waves on ECG most likely has atrial fibrillation. In hemodynamically stable patients with a relative contraindication to β-blockers (asthma and Raynaud syndrome), 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. The most appropriate treatment for this condition is primarily focused on obtaining appropriate rate control. First-line agents for rate control include β1 selective blockers such as metoprolol and esmolol and non-dihydropyridine calcium channel blockers such as verapamil and diltiazem. β-blockers are relatively contraindicated in patients with asthma and chronic obstructive pulmonary disease because these medications can worsen bronchoconstriction by activating β2-adrenoreceptors. Other relative contraindications to β-blockers include Raynaud disease due to possible exacerbation of vasoconstriction and depression due to 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. performed a randomized controlled trial comparing lenient versus strict rate control of heart rate in patients with atrial fibrillation. They 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. They recommend a lenient rate control strategy in patients with atrial fibrillation.

Figure/Illustration A is an ECG showing an absence of P waves as well as irregularly irregular RR intervals, which are most obvious in the rhythm strip (red circle). These findings are classically seen in patients with atrial fibrillation.

Incorrect Answers:
Answer 1: 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 is not a typical first line agent because it has multiple multi-system adverse effects such as pulmonary toxicity.

Answer 2: 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 such as apixaban.

Answer 3: 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.

Answer 4: 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 asthma, Raynaud syndrome, and depression, which makes calcium channel blockers 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.