Ivabradine reduces heart rate by blocking the funny current (If). This current flows through HCN (hyperpolarization-activated cyclic nucleotide-gated) channels. The unique clinical advantage of ivabradine over beta-blockers for rate control is:

• A It also blocks L-type calcium channels providing additional anti-anginal effect
• B It is superior to beta-blockers in acute myocardial infarction for reducing mortality
• C It causes reflex tachycardia due to vasodilation
• D It reduces heart rate without affecting myocardial contractility, AV conduction, or blood pressure ✓

Explanation

Ivabradine selectively inhibits the funny current (If) in SA node pacemaker cells, slowing spontaneous depolarisation and reducing heart rate without negative inotropy, dromotropic (AV conduction) effects, or vasodilation. This pure rate reduction is particularly beneficial in heart failure with preserved contractile function where negative inotropy from beta-blockers could be detrimental. Ivabradine is indicated for chronic stable angina (when beta-blockers are contraindicated) and HFrEF in patients with HR >70 bpm on maximally tolerated beta-blockers.

Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.

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Written and medically reviewed by the StethoPrep medical team.