March 7, 2013— -- A heart attack ended up killing Venezuelan president and longtime cancer sufferer Hugo Chavez, a source close to Chavez revealed. And cancer experts say that's not unusual.
Chavez died Tuesday at age 58 from a massive heart attack, according to the head of Venezuela's presidential guard. He had been battling an undisclosed form of cancer for 14 years.
"He couldn't speak but he said it with his lips ... `I don't want to die. Please don't let me die,' because he loved his country, he sacrificed himself for his country," Gen. Jose Ornella told the Associated Press.
Both cancer and chemotherapy treatments increase a person's risk of heart failure, said Dr. Jean-Bernard Durand, medical director of cardiomyopathy services at the MD Anderson Cancer Center in Houston.
"The number two killer of a cancer patient is heart disease, even if they're free of disease," he told ABCNews.com.
Kara Kennedy, the 51-year-old daughter of the late Sen. Edward Kennedy, is believed to have died from a heart attack in 2011 after undergoing lung cancer treatment several years earlier, Durand noted.
What's more, heart attacks are far more lethal in cancer patients than in non-cancer patients. The survival rate for a cancer patient who arrives alive at an emergency room is about 10 percent, compared with a 90 percent survival rate for a heart attack patient without cancer, Durand said.
Cancer is believed to cause blood clots more easily and chemotherapy thickens the blood, according to Durand. Lung cancer and radiation to the chest in particular ratchet up a cancer patient's risk of getting a heart attack.
Anti-cancer drugs such as anthracyclines, a mainstay of breast cancer chemo, as well as newer medications such as the drug Herceptin may cause heart damage by weakening the heart muscle, Dr. Timothy Moynihan, an oncologist at the Mayo Clinic in Minnesota said in a statement on the clinic's website.
Patients experiencing shortness of breath with minimal exertion or chest pain during cancer treatment should immediately tell their doctor, Moynihan wrote.
Cancer and heart attacks also share a common trigger: stress. Some studies suggest the use of beta blockers -- a standard heart medication -- may help ward off cancer, too.
"In addition to being beneficial to heart attack, [beta blockers] are beneficial to prevent progression of cancer," said Durand, who belongs to an expanding specialty known as "onco-cardiology" -- a blend of cancer and cardiology. Prevention is key, he added. Doctors should work with cancer patients to address heart issues such as high cholesterol before undergoing treatment to lessen the chance of heart disease.