Which is the most suitable addition to an antianginal therapy in a patient intolerant to isosorbide mononitrate?

Ranolazine is particularly suitable for this scenario as it serves as an antianginal agent that works through a different mechanism than isosorbide mononitrate, which is a nitrate. Specifically, ranolazine works primarily by inhibiting the late sodium current, thereby reducing intracellular calcium overload and improving myocardial function without significantly affecting heart rate or blood pressure. Its unique action can provide effective angina relief for patients who are intolerant to nitrates due to side effects such as headaches or hypotension that are commonly associated with isosorbide mononitrate.

The other medications listed may have some overlapping benefits but do not appropriately address the patient's specific intolerance to isosorbide mononitrate as effectively as ranolazine does. For example, while nifedipine and verapamil are both calcium channel blockers that can help with angina, they might not be ideal choices if the patient also has issues related to heart rate or if there are contraindications. Aspirin, while beneficial for cardiovascular prophylaxis and preventing thrombotic events, does not directly relieve angina symptoms and thus would not be an adequate addition for managing angina in a patient with nitrate intolerance.

Overall, ranolazine stands out as a safe and effective option to