Answer
Ivabradine acts on the sinus node, and its licensed uses require sinus rhythm. It may be ineffective when rhythms such as atrial fibrillation interfere with sinus-node function.
Sources for this answer
- Ivabradine 7.5mg film-coated tabletsemc · SmPC Current selected SmPC · Version 1
- Procoralanemc · SmPC Current selected SmPC · Version 22