Well nice question really.
There are two type of links.
1. One heart disease
2. Anxiety causing heart disease
For first, heart diseases or any diseases for that matter would make you feel anxious for your health status - it is natural and goes away when disease goes away. However, in case of long-standing , hard-to-treat disorders, it would be wise to consult a psychiatrist
for emotional rehabilitation
For second, the only time when anxiety causes heart disease are when they are both part of the same spectrum. This happens in people known to suffer from "Type A personalities" : worrisome, stressful personalities. Although no hard evidence exists but stress/anxiety can cause heart disease by following THEORIES:
a. increasing blood pressure. Increased blood pressure over long time can cause heart changes such as hypertrophy, and resultant ischemic chnages.
b. Causing atherosclerosis
- a degenrative disease of blood vessels which can affect any blood vessels in cardio-vascular system including coronary circulaion. This can lead to different conditions for example aortic valve insufficiency
But both these theories are not 100 %. These are just theories that have been put forward and not validated to date.