Ajmaline is an indole alkaloid primarily used in cardiology as a diagnostic agent for identifying certain arrhythmias, particularly Brugada syndrome. It acts by blocking sodium channels in cardiac cells, unmasking characteristic ECG patterns associated with the condition. This tool aids clinicians in confirming diagnoses and guiding treatment. While studied for antiarrhythmic effects, its therapeutic use is limited due to safer alternatives. In research, it is used to investigate ion channel function and cardiac electrophysiology. As a specialty chemical, ajmaline serves as a niche pharmaceutical intermediate and research reagent.