Cardiovascular disease

• 1. Introduction

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  Cardiovascular disease is the leading cause of death in every region of the world except Africa. In 2015 it killed 17.9 million people, which came to 32.1 percent of all deaths that year. A quarter-century earlier, in 1990, the figure was 12.3 million, or 25.8 percent. The category is enormous. It covers any disease involving the heart or the blood vessels, from coronary artery disease and stroke to heart failure, arrhythmia, valve damage, and aneurysms of the aorta.

  What makes this killer unusual is how much of it is avoidable. Researchers estimate that up to 90 percent of cardiovascular disease may be preventable if known risk factors are avoided. So why does it keep rising in much of the developing world while falling across most of the developed world since the 1970s? Why are men diagnosed seven to ten years earlier than women? And how does a process that begins quietly in childhood end up claiming tens of millions of lives a year? The answers run through diet, genetics, sleep, stress, and even the air people breathe.

• 2. Atherosclerosis And The Arteries

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  Intimal lesions appear in all the aortas and more than half of the right coronary arteries of children aged seven to nine years. That finding came from the Pathobiological Determinants of Atherosclerosis in Youth study, known as PDAY. It established that atherosclerosis, the major precursor of cardiovascular disease, begins in childhood. Coronary fatty streaks can start forming in adolescence.

  Atherosclerosis is the shared mechanism behind coronary artery disease, stroke, and peripheral artery disease. It can be driven by high blood pressure, smoking, diabetes, lack of exercise, obesity, high blood cholesterol, poor diet, excessive alcohol, and poor sleep. Coronary artery disease and stroke together account for 80 percent of cardiovascular deaths in males and 75 percent in females.

  Aging changes the arteries themselves. The mechanical and structural properties of the vascular wall shift, leading to loss of arterial elasticity and reduced arterial compliance. That stiffening may in turn lead to coronary artery disease. In the very elderly, large-artery pulsatility and stiffness are more pronounced in women than men, an effect tied to women's smaller body size and arterial dimensions rather than to menopause.

• 3. The Weight Of Age

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  Risk roughly triples with each decade of life, which makes age the single most important factor in developing cardiovascular disease. An estimated 82 percent of people who die of coronary heart disease are 65 and older. The risk of stroke doubles every decade after age 55.

  Serum cholesterol offers one explanation for why time matters so much. In most populations, total cholesterol rises as people age. In men, that increase levels off around age 45 to 50. In women, it keeps climbing sharply until age 60 to 65.

  The numbers describe an older population. In high-income countries, the mean age at first cardiovascular diagnosis sits around 70, specifically 73 in women and 68 in men. The average age of death from coronary artery disease is around 80 in the developed world, but only around 68 in the developing world.

• 4. Why Men And Women Differ

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  At the same age, men are about 50 percent more likely to develop cardiovascular disease. Coronary heart disease is two to five times more common among middle-aged men than women. In a World Health Organization study, sex accounted for roughly 40 percent of the variation in sex ratios of coronary heart disease mortality, and a second study found that sex differences explained nearly half the risk.

  Estrogen sits at the center of one leading explanation. As the predominant sex hormone in women, it may protect glucose metabolism and the hemostatic system, and may directly improve endothelial cell function. After menopause, estrogen production falls. That shift can push female lipid metabolism toward a more atherogenic form by lowering HDL cholesterol while raising LDL and total cholesterol.

  Some risks cut the other way for women. A woman with diabetes is more likely to develop heart disease than a man with diabetes. Women who have high blood pressure plus pregnancy complications carry three times the risk compared with women who had normal blood pressure and no such complications. One disease resists the pattern entirely. Thromboembolic diseases are similarly common in men and women.

• 5. Lifestyle Levers

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  Approximately 10 percent of cardiovascular disease is attributed to smoking, yet people who quit by age 30 have almost as low a risk of death as those who never smoked. The danger comes not only from smoking directly but from second-hand smoke. Tobacco is estimated to account for about 9 percent of cardiovascular deaths.

  Insufficient physical activity is the fourth leading risk factor for death worldwide. In 2008-31.3 percent of adults aged 15 or older were insufficiently active, broken down as 28.2 percent of men and 34.4 percent of women. Adults who do 150 minutes of moderate activity per week cut their risk of ischemic heart disease and diabetes by almost a third.

  Diet carries a large share of the burden. Dietary risk factors are associated with 53 percent of cardiovascular deaths. The World Health Organization links roughly 1.7 million deaths a year to low fruit and vegetable consumption, and in 2018 it estimated that trans fats caused more than half a million deaths per year.

  Alcohol complicates the picture. High levels of drinking clearly raise risk, and too much can cause high blood pressure, heart failure, and cardiomyopathy. Apparent protection from moderate drinking against stroke appears to be non-causal. At the population level, the health risks of alcohol exceed any potential benefit, and regular exercise can deliver the same upside more safely.

• 6. Hidden Triggers

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  Just 2.2 percent of teenagers in one study got enough sleep, and many of those did not sleep well. Short sleepers who get less than seven hours a night carry a 10 to 30 percent higher risk of cardiovascular disease. Recommendations call for at least eight or nine hours for adolescents and seven or eight for adults, yet about one-third of adult Americans fall short of seven. An estimated 50 to 70 million Americans live with insomnia, sleep apnea, or other chronic sleep disorders.

  Sleep patterns expose stark divides. African-Americans report short sleep five times more often than whites, possibly because of social and environmental factors. Black children and those in disadvantaged neighborhoods have much higher rates of sleep apnea. Among adults 45 and older, those who slept at irregular times and inconsistent hours were more likely to develop atherosclerosis.

  Psychological stress works as an independent threat. Only half of cardiovascular disease cases can be explained by unchangeable factors like age and gender, leaving the rest to sources that include stress. Depression affects more than 20 percent of patients with heart failure. Women who went through at least two divorces were as likely to develop cardiovascular disease as a smoker or a diabetic. During a World Cup soccer event in Germany, heart attacks more than doubled on the days the national team played.

  The air itself can injure the heart. Airborne particles under 2.5 micrometers in diameter, known as PM2.5, are the major focus of study. Over a short two-hour window, every 25 micrograms per cubic meter of PM2.5 raised cardiovascular mortality risk by 48 percent. After five days of exposure, blood pressure rose by 2.8 mmHg systolic and 2.7 mmHg diastolic for every 10.5 micrograms per cubic meter.

• 7. The Case For Prevention

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  Replacing saturated fat with polyunsaturated vegetable oil reduced cardiovascular disease by 30 percent in clinical trials. That figure anchors the argument that up to 90 percent of cardiovascular disease may be preventable when established risk factors are avoided. A diet high in fruits and vegetables lowers the risk of disease and death, and the Mediterranean diet may outperform a low-fat diet at producing lasting improvements in cholesterol and blood pressure.

  The numbers attached to specific interventions are striking. Statin treatment reduces cardiovascular mortality by about 31 percent. Stopping smoking cuts risk by about 35 percent. A 10 mmHg drop in blood pressure reduces risk by about 20 percent, and lowering blood pressure helps even within normal ranges. Among people with severe obesity, weight loss after bariatric surgery is linked to a 46 percent reduction in cardiovascular risk.

  Work and the heart are connected too. According to a 2021 World Health Organization study, working 55 or more hours a week raises the risk of stroke by 35 percent and the risk of dying from heart conditions by 17 percent, compared with a 35 to 40 hour week. In 2023, the American Heart Association developed PREVENT-ASCVD, a trademarked tool that measures potential risks of cardiovascular disease, heart failure, and atherosclerotic cardiovascular disease.

• 8. Treating The World's Top Killer

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  A single quality-adjusted life-year bought with aspirin or atenolol costs less than 25 US dollars, a figure that captures how cheaply some heart-attack treatments deliver benefit. The same comparison priced streptokinase at about 680 dollars and tissue plasminogen activator at 16,000 dollars. Aspirin, ACE inhibitors, beta-blockers, and statins combined for secondary prevention came to 350 dollars per quality-adjusted life-year in low- and middle-income regions.

  Surgery and devices extend lives when medication is not enough. A diseased heart valve can be replaced through surgery. A pacemaker can reduce abnormal rhythms for people with arrhythmias. After a heart attack, options include coronary angioplasty and coronary artery bypass surgery. Even influenza vaccination may lower the chance of cardiovascular events and death in people with heart disease.

  The geography of the disease points to where the next fight will be hardest. Over 80 percent of global cardiovascular deaths occur in low- and middle-income countries, and by 2030 more than 23 million people are projected to die from these diseases each year. An estimated 60 percent of the world's cardiovascular burden will fall on the South Asian subcontinent, even though it holds only 20 percent of the world's population. To confront that imbalance, the Indian Heart Association is working with the World Heart Federation to raise awareness.