Heart attack survivors who are sarcastic or cynical are at greater risk of dying within two years of another heart attack, researchers have found.
More than 2,300 people took part in the American study which signed up patients who had just survived a heart attack.
It found those who displayed hostile character traits - including sarcasm, cynicism, resentment, impatience or irritability - were at much greater risk of dying of a second attack within the next two years.
It is thought this may be due to their emotional state being consistently negative which puts a strain on their health.
The team at the University of Tennessee in the US, measured the hostile traits at the beginning of the study using a personality test and the patients were then followed for 24 months.
The report read: "Hostile individuals have increased clotting times, higher adrenaline levels, above normal cholesterol and triglyceride levels, and increased cardiac reactivity.
"These known inflammatory factors may initiate cardiac events and increase poor clinical outcomes."
Previous research also showed that being optimistic has a direct impact on cardiovascular health by reducing stress hormones, pulse rate and blood pressure.
Study author Tracey Vitori said: "Hostility is a personality trait that includes being sarcastic, cynical, resentful, impatient or irritable.
"It's not just a one-off occurrence but characterises how a person interacts with people.
"We know that taking control of lifestyle habits improves the outlook for heart attack patients and our study suggests that improving hostile behaviours could also be a positive move."
