Why is there a potential issue if you have heart disease when using diclofenac sodium topical gel?

There might be a potential issue due to the increased risk of heart problems such as heart attack or stroke when starting or increasing diclofenac sodium topical gel. Talk to your healthcare professional right away if you have any symptoms of heart problems such as chest pain or pressure, pain spreading to your arm, jaw or shoulder, shortness of breath, or fainting.