Heart disease patients are not aware of heart attack symptoms, which might affect the treatment’s effectiveness, a new study published in the Archives of Internal Medicine finds.

A team of researchers from School of Nursing at the University of California, San Francisco led by Kathleen Dracup looked at 3,522 patients in the U.S., Australia and New Zealand who had previously suffered a heart attack or had undergone procedures, such as angioplasty.

The results showed that 44 percent of these patients were poorly informed about heart attack symptoms. The study also revealed that women, the most educated patients, younger patients, those who had undergone cardiac rehabilitation, and those treated by a heart specialist not a family doctor appeared to be better informed about heart symptoms.

It is already known that survival rates improve by up to 50 percent if the patients receive treatment within one hour. Delaying treatment by 30 minutes cuts the mean life expectancy by a year.

“Although knowledge about heart disease and its symptoms is not sufficient to reduce delay in treatment, it’s necessary for patients to have this information so they can quickly identify symptoms of acute coronary syndrome and take prompt action to seek care,” the scientists wrote in the study.

According to the American Heart Association, there are four major signs that could mean you are at risk of a heart attack. They include chest discomfort that lasts more than a few minutes or goes away and comes back; discomfort in one or more arms, the back, neck, jaw or stomach; shortness of breath with or without chest discomfort and breaking out in cold sweat, nausea or lightheadedness.

The study comes to underline the findings of another report by the Centers for Disease Control and Prevention earlier this year, which said that only 27 percent of adults would recognize all heart attack warning signs and would call emergency services if they suspected someone were having a heart attack or stroke.

More than 900,000 Americans suffer a heart attack each year, and about 157,000 of them are fatal.