Might it be possible that a a lot of anxiety and stress cause a heart attack in a person with a healthy heart?

Not directly: Anxiety and stress can cause arrhythmias, including serious ones that may be life threatening, but those are not technically a heart attack. Psychosocial stresses often are associated with poor lifestyle habits (diet, weight, lack of exercise, cigarette use) that may contribute to heart attack risks.

Rare: Pts with an acute or traumatic life altering event has been known to cause chest pain ekg changes and a wall motion abnormality in the front of the heart on echo . The cardiac enzymes will rise as well . When a heart cath is done no blockage is found . This has been dubbed " broken heart syndrome " . Presumeable cause is from the catacholamines ie adrenaline rush that affects the heart