In a new study of more than 9,000 people, silent heart attacks—with warning signs so quiet or so unusual that people didn’t seek medical help—were nearly as common as classic heart attacks with well-known symptoms like crushing chest pain. And they were almost as lethal in the long run, tripling the odds of dying during the 9-year study compared to people who didn’t have a heart attack of any kind.
It’s a wake-up call for anyone at risk for heart disease, but heart experts say people with type 1 and type 2 diabetes should pay particular attention. “People with diabetes are at higher risk for silent heart attacks for several reasons,” says Om P. Ganda, M.D., medical director of the Lipid Clinic at the Joslin Diabetes Center in Boston and an associate clinical professor of medicine at Harvard Medical School. “High blood sugar can lead to autonomic nerve damage that reduces the ability to feel pain, including heart-attack pain. Your only symptom might be shortness of breath. And people with diabetes are already at two to three time’s higher risk for heart disease than people without diabetes, which also increases the chances for a silent heart attack.”
In a 2013 British study of 5,102 people with type 2, heart tests showed that 16%— about one in six—had likely had silent heart attacks. People with type 1 diabetes may also be at higher-than-average risk, Dr. Ganda says, due to nerve damage and overall heart-disease risk.
Lead researcher Elsayed Z. Soliman, M.D., MSc., M.S., director of the epidemiological cardiology research center at Wake Forest Baptist Medical Center, Winston-Salem, North Carolina, says silent heart attacks are dangerous because they cut off the flow of oxygen-rich blood to areas of heart muscle just like a classic heart attack does.
But while a classic heart attack gets medical attention such as artery-clearing surgery to restore blood flow fast to heart muscle, a silent one doesn’t. “So the heart is under more stress in the future,” he says. That can lead to another heart attack or raise risk for congestive heart failure – when the heart is too weak to pump enough blood to the rest of the body. “Heart muscle may already be weakened by diabetes or even by some medications used to treat diabetes,” Dr. Ganda notes. “So adding a silent heart attack could make matters worse.”
According to Dr. Ganda and Dr. Soliman, people with diabetes should know these three things about silent heart attacks: