Heart disease is the leading killer of men and women in America — and it has been for more than 100 years, despite major gains in public health.
For years, doctors have known that high blood pressure, high cholesterol, diabetes and smoking raise the risk of cardiovascular disease. They typically use these factors to calculate patients’ individual risk — and to guide treatment recommendations. But in recent years, experts have started thinking more broadly about what drives cardiovascular disease risk.
With smoking on the decline, and with better cholesterol and blood pressure treatments now available, death rates from heart attack and stroke have fallen in the last half-century, said Dr. Sadiya Khan, a preventive cardiologist at the Feinberg School of Medicine at Northwestern University. But several factors now threaten to slow — or even undo — that progress, including the rise of metabolic conditions like obesity and diabetes and increasing rates of heart failure.
In recognition of these changes, the American Heart Association last year released a new risk calculator, called PREVENT, that includes measures of metabolic and kidney health and makes it possible for doctors to predict the risk of heart failure in addition to that of heart attack and stroke.
“I don’t think the main risk factors for cardiovascular disease have necessarily changed,” said Dr. Michael Nanna, an interventional cardiologist at Yale School of Medicine. “But I think there’s an increased recognition of a broader set of risk factors than we as cardiologists thought about traditionally.”
The big risk factors remain.
Conditions that lead to plaque buildup on the inside walls of blood vessels are a big concern. As plaques grow, they narrow the space available for blood to flow, which can cause symptoms like chest pain. Eventually the plaques can break off and block an artery that carries blood to the heart or brain, causing a heart attack or stroke, explained Dr. Jeremy Sussman, an associate professor of internal medicine at University of Michigan Medical School.
High cholesterol: Cholesterol is a main component of plaque. Though cholesterol is essential for body functions like making hormones and vitamins, when it’s too high it can accumulate on artery walls, combining with fat, calcium and other substances from the blood to form plaques, said Dr. Khan, who led the American Heart Association committee that developed the new risk calculator.
High blood pressure: Hypertension can damage arteries, forcing them to strain and become rigid instead of remaining elastic. That can increase plaque buildup, Dr. Khan said. High blood pressure also stresses the heart. This increases the risk for heart failure, which happens when the heart muscle can’t pump enough blood to meet the body’s needs for blood and oxygen.
Diabetes: People with Type 1 or Type 2 diabetes are more likely to have high or unbalanced cholesterol and high blood pressure — and having both diabetes and one of these additional risk factors compounds the likelihood of heart disease, Dr. Khan said.
Age: Age is thought to increase your risk of heart disease partly because the damage to blood vessels from cholesterol and blood pressure accumulates over time, Dr. Sussman said.
Smoking: Smoking is like accelerated aging, Dr. Khan said. “For the same cholesterol level or the same blood pressure level, your blood vessels will look worse,” she said. That not only means more plaque, but it also increases the likelihood that the plaque will break off and form a blood clot.
Smoking also causes inflammation, which is a common theme underlying all of the risk factors for heart disease, doctors said. Research increasingly suggests that inflammation plays an important role in the development of plaques and their rupture.
Sex: Men generally are considered to be at greater risk, though heart disease is also the leading killer of American women, whose risk tends to increase after menopause.
Metabolic health is also considered important.
Risk factors for heart disease rarely exist in isolation. “Most people don’t just have hypertension, or just have diabetes,” Dr. Khan said.
Recognizing the overlap among heart disease, kidney disease and metabolic conditions and their shared underlying mechanisms, the American Heart Association last year coined the term “cardiovascular-kidney-metabolic syndrome” to define this cluster of related health issues.
A key initial factor in developing the syndrome, according to the paper describing it, is the accumulation of excess and dysfunctional fat tissue, particularly in the abdomen. This can lead to inflammation, insulin resistance and, eventually, diabetes, chronic kidney disease and heart disease.
For this reason the new calculator includes inputs like body mass index (a controversial but widely used measure of obesity) and estimated glomerular filtration rate, which tells doctors how well your kidneys are working.
Doctors can also use hemoglobin A1C, an indicator of average blood sugar over three months, and urine albumin-to-creatinine ratio, a measure of how healthy your kidneys are, to estimate risk in a more granular way in higher-risk patients.
Race matters.
Black Americans are at a greater risk of dying from cardiovascular disease than white Americans. On average, they develop high blood pressure and diabetes four to six years earlier than their white peers, Dr. Khan said, and they also have higher rates of advanced kidney disease. South Asians and Native Americans are also at higher risk of cardiovascular disease, Dr. Nanna said.
Because of these differences, an older risk calculator used different formulas for Black and white people. There was no separate option for people of other races because historically there was limited data on those groups.
The American Heart Association removed race as a stand-alone consideration in its new risk calculator. This was to recognize that race is a social construct, not a biological factor, Dr. Khan said. Race still matters when it comes to cardiovascular disease risk, she said, but in developing the PREVENT equations, the committee found that racial disparities were captured by other risk factors and that the model accurately predicted risk across racial groups.
The calculator does include ZIP code in an effort to capture elements of “social deprivation,” such as low income or unemployment, that can affect health outcomes.
Calculators are just one piece of prevention.
High cholesterol, high blood pressure, obesity and diabetes can be treated with medications or lifestyle changes, like adopting a healthy diet and exercising. Quitting smoking can also significantly reduce the risk of heart attack or stroke.
“We definitely want to make sure that we’re addressing any risk factor that’s low-hanging fruit,” Dr. Nanna said.
Some risk factors, including racial background and family history, are out of people’s control but still relevant to treatment decisions, doctors said. Somebody who has a significant family history — a parent who had a heart attack before 50, or multiple close family members with heart disease — may warrant a closer look or treatment even if that person’s risk score is low, Dr. Sussman said.
Studies have found that the new calculator estimates people’s risk of heart disease as roughly 50 percent lower, on average, than older calculators did, raising concerns that fewer people would meet the threshold for being prescribed a statin or an antihypertensive drug. But Dr. Khan and others said that previous calculators had been overestimating risk because they relied on old data, from when heart attack and stroke rates were higher, and noted that the thresholds for medication may change as the new tool is adopted.
Whatever the calculator used, doctors said they need to get the clearest picture possible of heart disease risk and potential benefits of treatment for any given patient. “Waiting until people have this disease is not going to be our solution,” Dr. Khan said. “We need prevention.”
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