Review Question - QID 216428

This patient with a history of rheumatic heart disease presents with intermittent palpitations, dizziness, mitral stenosis (diastolic rumbling murmur), and ECG changes that show an irregularly irregular rhythm with no discernible P waves, indicative of atrial fibrillation. Diltiazem is a non-dihydropyridine calcium channel blocker that can be used to manage atrial fibrillation and has side effects that include peripheral edema, constipation, flushing, dizziness, and AV block.

Atrial fibrillation can be asymptomatic, though symptomatic patients classically present with palpitations, lightheadedness, dizziness, fatigue, and syncope. Treatment of newly diagnosed atrial fibrillation focuses on either rate or rhythm control, the former of which can be achieved by class II and IV antiarrhythmics. Class II antiarrhythmics include beta-blockers, which decrease cAMP and close membrane calcium channels in the sinoatrial (SA) and atrioventricular (AV) nodes. Class IV antiarrhythmics include non-dihydropyridine calcium channel blockers, which inactivate L-type calcium channels in the SA and AV nodes. Patients who are hemodynamically unstable should be cardioverted. Pharmacologic management should also include anticoagulation, based on an assessment of the CHA2DS2-VASc (congestive heart failure, hypertension, age ≥ 75 years, diabetes mellitus, stroke or transient ischemic attack (TIA), vascular disease, age 65 to 74 years, sex category) and HAS-BLED score and personalized to the patient's own risk profile (for example, blood thinners should not be given to elderly patients with frequent falls and head injuries given the risk of bleeding).

Gutierrez and Blanchard review atrial fibrillation and its management. They note that the diagnosis is confirmed with ECG though paroxysmal atrial fibrillation may be missed on a single ECG thus telemetry may be needed. They recommend treatment with rate control agents and blood thinners for most patients.

Figure/Illustration A is an ECG showing an irregularly irregular rhythm with no discernible P waves. This pattern is indicative of atrial fibrillation. Note the irregular spacing of the QRS complexes (blue arrows).

Incorrect Answers:
Answer 1: Amiodarone is a class III antiarrhythmic with certain class I, II, and IV properties that can be used for atrial fibrillation rhythm control. Side effects of amiodarone include hepatotoxicity, pulmonary fibrosis, hyper/hypothyroidism, and photodermatitis. Rhythm control is not the recommended first-line treatment of atrial fibrillation. The many side-effects make amiodarone a less desirable treatment as well.

Answer 3: Flecainide is a class IC antiarrhythmic that can be used for rhythm control. Side effects of flecainide include arrhythmias, visual disturbances, and dizziness. Rate control agents are preferred in the management of atrial fibrillation.

Answer 4: Lidocaine is a class IB antiarrhythmic that treats ventricular dysrhythmias, not atrial fibrillation. Side effects of lidocaine include tremors, paresthesias, and convulsions. Ventricular tachycardia in a stable patient could be treated with this medication. Ventricular tachycardia presents with a wide-complex tachycardia and often causes hemodynamic instability.

Answer 5: Propranolol is a class II antiarrhythmic that can be used for rate control. Class II antiarrhythmics are typically first-line treatment for atrial fibrillation as they provide a mortality benefit. However, side effects of propranolol include AV block, neurological symptoms (seizures, sedation, sleep alteration), erectile dysfunction, and exacerbation of asthma or COPD. This patient's side-effects suggest that verapamil was started.

Bullet Summary:
Diltiazem is a non-dihydropyridine calcium channel blocker that can be used for rate control in atrial fibrillation and may cause side effects including: peripheral edema, constipation, flushing, dizziness, and AV block.