Can a paroxysmal atrial fibrillation and av node reentry tachycardia increase the risk for a heart attack?

Yes: These dysrhythmias can lead to a malignant dysrhythmia such as ventricular fibrillation; the cause of sudden death.

Complicated Answer: This is a tough one. If you already have severe coronary disease, fibrillation can produce rapid heart rates which exceed the available blood supply and lead to a heart attack due to "demand ischemia." the same is true, though even more rare for avnrt. Afib, but not avnrt is often a marker of (is seen with) other heart disease which of course puts you at increased risk of heart attack.