I need to calm down
No, the conclusion from the fact given is not at all clear. People who get mad more easily do so for a reason--a more stressful job, bad genes, or some other mysterious factor X. Maybe it is the X factor, rather than the anger itself, that is bad for you. Maybe reducing anger without changing X won't change health outcomes at all.
Researchers at Johns Hopkins School of Medicine tracked 1,055 medical students for 36 years. Compared with cooler heads, the hotheads were six times more likely to suffer heart attacks by age 55 and three times more likely to develop any form of heart or blood vessel disease.
The conclusion is clear: Anger is bad for you at any age.
I am going to call the author and give him a piece of my mind. Just as soon as this pain in my chest goes away.