Vemakalant is primarily used in the treatment of recent-onset atrial fibrillation, a common type of irregular heartbeat. It works by helping to restore normal heart rhythm quickly and effectively. This makes it particularly valuable in clinical settings where rapid conversion to a regular rhythm is necessary to prevent complications. It is often administered intravenously in hospitals under close medical supervision to ensure safety and monitor the patient's response. Its ability to act quickly makes it a useful option for managing acute episodes, especially when other treatments may not be suitable or effective.