Can anxiety cause a silent heart attack or angina?

Not by itself. Stress does contribute to heart attacks, but does not directly cause them. Family history, diabetes, high blood pressure, hyperlipidemia and smoking are the known risk factors. Occasionally, even people without CAD will feel tightness in their chest when anxious, hyperventilating, or tightening their musculature. Of course, if their is any question, one should seek care by their pcp or er.
Yes. Significant stress, from any cause, whether it be extreme physical exertion, emotional distress or extreme anxiety can precipitate a myocardial infarction. This is especially true if there is a favorable substrate for such an event like pre-existing coronary artery disease or other known cardiovascular risk factors.