Usually, the effects become apparent later during a routine electrocardiogram (EKG), when it’s discovered that some areas of the heart aren’t functioning properly. The risk of advanced disease and premature death is high for those whose silent heart attacks are left untreated.
Silent heart attacks are not rare. In the view of Dr. Paul M. Reiter of Mid-Valley Cardiology in Kingston, they’re not really silent, just misperceived. “Scientifically known as silent ischemia, there usually are some symptoms, such as chest discomfort, nausea, light-headedness, slight pain in the arms and general malaise,” said Reiter.
Women seem to have silent ischemia a little more often than men. “We don’t know why. It just is,” Reiter said, adding, “There may be soreness in the chest, arms of jaw that goes away after resting, or shortness of breath and fatigue. In a significant number of women, people with diabetes and those over the age of 65, a heart attack comes without any symptoms.”
Dr. Craig Moss, a specialist in internal medicine and elder care at Medical Associates of the Hudson Valley, says about 30% of patients who have had heart attacks don’t realize it. Moss defines silent ischemia as a partial blockage of blood vessels that supply the heart, causing a chronic shortage of oxygen. The blockage results from a progressive narrowing of the arteries from accumulations of cholesterol plaque. Risk factors include obesity, depression, stress, hypertension and family history.
The high incidence of silent ischemia among diabetics may be the result of an impaired autonomic system, which interferes with pain perception, said Moss. Women, he said, have a significant system of small blood vessels, which may lead to complications with subtle symptoms. Most evidence of silent heart attack is found on EKGs taken after an outright heart attack.
The heart has a reserve capacity that allows it to suffer some scarring and weakening and still meet the body’s needs. But repeated episodes of silent ischemia can deplete the heart’s reserve capacity. Although a complete and prolonged blockage, or myocardial infarction, results in death, the partial impairment caused by silent ischemia is reversible. “It can be treated before it reaches the heart attack stage, if it’s discovered,” Moss said.
Three layers of treatment
Are arteries are blocked by blood clots, cholesterol plaque or both? “Ischemia damages blood vessel walls and limits blood flow,” Reiter explained. “Cholesterol and cell debris builds up, narrowing the arteries. Blood clots may form on the plaque, or a piece of plaque can break off and block blood flow further.”
Reiter outlines three levels of treatment, from prevention to medication to possible surgery. Lifestyle adjustments are the first line of defense against the heart attack: stop smoking, adjust your diet to lose weight, reduce cholesterol, and exercise regularly.
Intake of foods of animal origin (except fish) should be reduced because they contain saturated fat, which increases artery-narrowing cholesterol. Fish contains unsaturated fat, which is good for the heart. Fried foods are to be avoided. Intake of complex carbohydrates including vegetables, fruits legumes and whole grains should be increased. Salt intake should be limited to less than five grams per day. Smoke contains carbon monoxide, which induces the deposit of fat in blood vessels. Nicotine raises blood pressure and increases the need for oxygen, the doctors explained.
Those at high risk of ischemia may be given regular stress tests to detect changes in heart function, according to Reiter. Though aspirin may be a good idea to prevent heart attacks in some people, he said, it’s not always advisable. Medications may be prescribed. A nuclear stress test, which tracks the heart’s functioning via a radioactive marker, can be undertaken. Finally, there are surgical options.
Other means of detection
In addition to regular stress tests, Reiter advises using a Holter monitor, worn like a halter for 24 hours, to track heart function in at-risk patients. Medicines that may be prescribed include beta blockers, which prevent adrenalin from speeding up the heart, anti-platelet drugs, calcium channel blockers to dilate coronary arteries, and long-acting nitrates.
If further treatment is needed, radioactive elements may be injected into the body to diagnose heart problems. This technique relies on the emission of gamma rays, which provide contrast to soft tissue. This “myocardial perfusion scanning” is the most common cardiac scanning associated with nuclear medicine. Though expensive, it’s vital for information about the blood flow. It allows doctors to assess how heart disease is affecting oxygen uptake in different parts of the heart. Surgery may follow if indicated.
Although there’s no age group per se that’s prone to silent ischemia, according to Moss, ambulatory monitoring for signs of shortness of breath, dizziness and nausea may warn of a mild heart attack in the elderly. Two to four percent of middle-aged men with no previous heart-attack experience silent ischemia. The percentage rises to ten percent in men who have had heart attacks previously. “In patients who have been treated for heart attacks, fifteen percent to thirty percent have had heart disease previously that they didn’t know about,” Moss said.
The same causes that apply to any risk of heart attack apply to the undetected or silent ones: poor diet, high cholesterol, hypertension, smoking, obesity, depression, stress and family history. The best preventatives are healthy lifestyle, good diet, exercise, and stress reduction.
Does the ingestion of vitamins help prevent heart disease? New studies under way indicate that Vitamin D may benefit the heart, Moss said. “While it’s true that we can’t always get adequate sun exposure, and in an older person the skin doesn’t absorb much Vitamin D, we still don’t know what role that plays in the heart. But it stands to reason that if levels are low it doesn’t hurt to take Vitamin D.”
Reiter agreed that low levels of vitamin D were associated with all types of problems, and that because Vitamin D is cheap it doesn’t hurt to bring them up. “But,” he observed, “the best prevention for a heart attack is the same wholesome lifestyle that makes us healthy in all other ways.”++