Which rhythm is commonly managed with calcium channel blockers for rate control?

• A. Atrial fibrillation
• B. Sinus bradycardia
• C. Second-degree AV block
• D. Ventricular tachycardia

Answer: (A)

Calcium channel blockers work by slowing conduction through the AV node, which reduces how quickly impulses travel to the ventricles. In atrial fibrillation, the atria fire rapidly, but the ventricular rate is largely governed by AV nodal conduction. By blocking those calcium channels, non-dihydropyridine agents like diltiazem or verapamil raise the AV nodal refractory period and slow ventricular rate, helping to improve cardiac filling and hemodynamics and prevent tachycardia-related cardiomyopathy.

This approach would not be appropriate for sinus bradycardia because further slowing of the heart rate could worsen bradycardia. It’s also not suitable for second-degree AV block, since additional AV nodal delay or block could progress the block. For ventricular tachycardia, rate control with calcium channel blockers is not effective and can be unsafe; antiarrhythmic strategies or other acute treatments are used instead.