A 48-year-old woman with heart failure (EF 35%) remains symptomatic with a resting heart rate of 88 per minute despite maximum tolerated beta blocker therapy. Her blood pressure is 104/68 mmHg. Which drug slows the sinus rate without lowering blood pressure?

• A Digoxin
• B Diltiazem
• C Metoprolol succinate
• D Ivabradine ✓

Explanation

Ivabradine selectively blocks the funny current (If) in the sinoatrial node, slowing spontaneous depolarization and heart rate without affecting blood pressure, contractility, or conduction. Diltiazem lowers blood pressure and depresses AV conduction, metoprolol already failed at maximum tolerated dose, and digoxin controls rate mainly in atrial fibrillation and has minimal effect on sinus rate in sinus rhythm. Ivabradine requires sinus rhythm above 70 beats per minute to be useful.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.