Voltarol (Diclofenac) was another one of these NSAIDs that caused heart problems as well as stomach ulcers. There were several other drugs with 'coxib' in the name that gave similar symptoms, such as Vioxx (Rofecoxib).
I'm no drug expert, but Voltarol was changed from being Diclofenac, Sodium salt to Diclofenac, Potassium salt - was this to possibly circumvent bad reports about the Sodium version?
Naproxen may also be in the same category with heart attack risks.