Which type a personality characteristic is the key trait that is linked to heart disease?

Answer: Hostility

Explanation:

Type A individuals are tend to be easily affected by anger or hostility. These traits they may or may not express in their behavior. Such kind of individuals tend to see worst in others.

When they express their behavior they express overtly. Hostility can be considered as the main factor link to the heart diseases this appears due to hidden stress, aggression and increase in the blood pressure or hypertension.