Heart attack victims in the United States are becoming younger and fatter, a new study reveals.

The average age of people suffering the deadliest heart attacks fell from 64 years old to 60 years old over the past two decades, Cleveland Clinic researchers report. And obesity is now implicated in 40 percent of severe heart attacks.

Heart attack sufferers are also more likely to smoke and have high blood pressure, diabetes and chronic obstructive pulmonary disease (COPD) than patients of 20 years ago, the researchers found.

This new profile is raising alarms.

"Lifestyle changes to reduce weight, eat right, exercise and quit smoking are critical for prevention of heart attack," said senior researcher Dr. Samir Kapadia, a professor of medicine and section head of interventional cardiology.

Working toward these heart-healthy improvements is a job for doctors at routine checkups as well as patients, he said.

For the study, researchers analyzed heart disease risk factors among more than 3,900 patients treated for ST-elevation heart attacks (STEMI). This type of heart attack -- which happens when a main heart artery is completely blocked by plaque -- carries a high risk of disability and death, the researchers said.

Kapadia and his colleagues found that from 1995 to 2014, the average age of STEMI patients dropped from 64 to 60, and the prevalence of obesity increased from 31 percent to 40 percent.

Also, the proportion of heart attack patients with diabetes rose from 24 percent to 31 percent. High blood pressure was reported in nearly four out of five cases, up from 55 percent. And COPD, usually the result of smoking, increased from 5 percent to 12 percent.

The new findings are consistent with other recent data on heart attack patients, said Dr. Gregg Fonarow, a professor of cardiology at the University of California, Los Angeles.

"Substantially increased efforts are needed to improve heart health to further reduce the rates of cardiovascular events and premature cardiovascular deaths," he said.

The study authors were surprised to find smoking had increased from 28 percent to 46 percent of heart attack patients -- even though smoking rates in the United States as a whole have declined over the past 20 years, the researchers said.

And, the proportion of patients with three or more risk factors increased from 65 percent to 85 percent, they found.

"Primary care physicians and cardiologists have to work harder to provide education and specific programs to help reduce risk factors in the community to reduce the burden of heart attack," Kapadia said.

Doctors can coach patients and provide practical plans for a heart-healthy lifestyle, he said. And patients need to stick to their efforts, he added.

"Patients should take responsibility and place health as the highest priority to change their lifestyle in order to prevent heart attacks," Kapadia said.

The study results are scheduled for presentation April 4 at the American College of Cardiology's annual meeting, in Chicago.

Research presented at meetings is usually considered preliminary until published in a peer-reviewed medical journal.