Cardiovascular disease is caused by a combination of arterial damage, chronic inflammation, and the gradual buildup of fatty deposits inside blood vessel walls. It killed 19.2 million people globally in 2023, making it the leading cause of death worldwide. While genetics account for an estimated 40% to 60% of your risk, the majority of cases involve modifiable factors: high blood pressure, high blood sugar, smoking, poor diet, and physical inactivity working together over years to damage the cardiovascular system.
How Plaque Builds Up in Your Arteries
The underlying process behind most cardiovascular disease is atherosclerosis, a slow accumulation of fatty material inside artery walls. It begins when the endothelium, the thin inner lining of your blood vessels, gets damaged. That damage can come from high blood pressure, tobacco chemicals, high blood sugar, or other irritants. Once the lining is compromised, LDL cholesterol (the “bad” cholesterol) seeps into the artery wall and becomes oxidized, triggering an immune response.
White blood cells rush to the site and swallow the oxidized LDL, turning into bloated “foam cells” that release inflammatory signals. Platelets stick to the damaged area and recruit even more immune cells. Over time, smooth muscle cells migrate into the growing deposit and form a fibrous cap over it, creating what we recognize as plaque. As lipids continue to accumulate, cells inside the plaque begin to die, leaving behind a soft, unstable core. If that fibrous cap ruptures, a blood clot forms instantly, and that clot can block blood flow to the heart (heart attack) or brain (stroke).
High Blood Pressure
Chronically elevated blood pressure is one of the most powerful drivers of cardiovascular disease. The extra force pounding against artery walls directly damages the endothelium, which sets the stage for plaque formation. But the damage goes further: the body responds to that constant mechanical stress by thickening and stiffening the artery walls. Collagen production ramps up while elastin, the protein that keeps arteries flexible, breaks down faster than it can be replaced.
This creates a destructive feedback loop. Stiffer arteries push systolic blood pressure (the top number) even higher, which hardens arteries further, triggering more inflammation and calcification. The heart also suffers directly. To push blood through increasingly rigid vessels, the left ventricle thickens and enlarges, a condition called left ventricular hypertrophy that raises the risk of heart failure.
Current guidelines from the American Heart Association define normal blood pressure as below 120/80 mmHg. Stage 1 hypertension starts at 130/80, and stage 2 hypertension begins at 140/90. Many people with readings in the 130s have no symptoms, which is why high blood pressure often causes damage for years before it’s detected.
High Blood Sugar and Insulin Resistance
Insulin resistance, the hallmark of type 2 diabetes and prediabetes, doesn’t just raise blood sugar. It fundamentally changes how your blood vessels function. Normally, insulin helps blood vessels relax by stimulating the production of nitric oxide, a molecule that keeps arteries flexible and open. When cells stop responding properly to insulin, that protective pathway gets suppressed. Instead, a different signaling pathway takes over, one that promotes inflammation, constricts blood vessels, and encourages smooth muscle cells in artery walls to multiply.
High blood sugar also generates reactive molecules that damage proteins throughout the body, creating compounds that stiffen blood vessel walls and accelerate aging in arterial tissue. On top of that, the oxidative stress caused by insulin resistance further impairs nitric oxide production and activates inflammatory signals that make atherosclerosis progress faster. This is why people with type 2 diabetes face roughly double the risk of heart attack and stroke compared to people with normal blood sugar, even when other risk factors are controlled.
Smoking and Tobacco Use
Tobacco smoke attacks the cardiovascular system through multiple channels simultaneously. Nicotine constricts coronary arteries by activating the same receptors that respond to adrenaline, reducing blood flow to the heart. It also directly injures endothelial cells. Studies on people who had never smoked before found that after smoking tobacco cigarettes for experimental purposes, they had elevated numbers of damaged endothelial cells circulating in their blood and increased platelet clumping. These effects did not occur with non-tobacco cigarettes, confirming nicotine’s role in the damage.
Carbon monoxide, another component of cigarette smoke, binds to red blood cells and reduces their ability to carry oxygen. The body compensates by producing more red blood cells, which thickens the blood and makes clotting more likely. Combined with the endothelial damage from nicotine and the oxidizing chemicals in smoke, this creates an environment where plaque forms faster and dangerous clots are more likely to develop.
Diet and Ultra-Processed Foods
What you eat shapes cardiovascular risk through several pathways. Diets high in saturated fat raise LDL cholesterol, providing more raw material for plaque buildup. Excess sodium contributes to high blood pressure. But research increasingly points to ultra-processed foods as a distinct risk factor beyond their individual ingredients. A large prospective study found that people who consumed the most ultra-processed food had a 19% higher risk of dying from cardiovascular disease compared to those who ate the least, after accounting for other lifestyle and health factors.
Ultra-processed foods tend to be calorie-dense and nutrient-poor, promoting weight gain and the metabolic dysfunction that comes with it. They also contain additives, emulsifiers, and industrial compounds that may independently promote inflammation in the gut and bloodstream. Diets rich in vegetables, fruits, whole grains, legumes, and fish consistently show the opposite effect, lowering inflammation, improving cholesterol profiles, and reducing blood pressure.
Physical Inactivity and Obesity
A sedentary lifestyle contributes to cardiovascular disease both directly and by amplifying other risk factors. Regular physical activity improves how your body handles insulin, lowers blood pressure, raises HDL (“good”) cholesterol, and reduces chronic inflammation. Without it, all of those protective effects are lost. Excess body fat, particularly fat stored around the abdomen, acts as an active endocrine organ, releasing inflammatory molecules that promote endothelial dysfunction and insulin resistance. Obesity also increases blood volume, forcing the heart to work harder even at rest.
Genetics and Family History
Twin and family studies estimate that 40% to 60% of coronary artery disease risk is heritable. Some of this comes from genes that directly affect cholesterol metabolism. Variants in the LDLR gene reduce the liver’s ability to clear LDL cholesterol from the blood. Variants in the PCSK9 gene affect how LDL receptors are recycled. Changes in LPA, the gene for lipoprotein(a), carry one of the strongest single-variant effects, with one version increasing coronary disease risk by about 42%.
However, the genetics of heart disease are complex. Researchers have identified over 200 independent genetic variants linked to coronary artery disease risk, but together they explain only about 28% of the estimated heritable component. Most individual variants have small effects, each raising risk by 6% to 8%. This means that for the vast majority of people, genetic risk expresses itself through the same mechanisms (higher cholesterol, more inflammation, stiffer arteries) that lifestyle changes can counteract. A strong family history of early heart disease is worth knowing about, not because it’s a sentence, but because it tells you how aggressively to manage the modifiable risks.
Chronic Inflammation
Inflammation runs through nearly every cause of cardiovascular disease. It’s the common thread connecting high blood pressure, insulin resistance, smoking, obesity, and even air pollution to actual arterial damage. One way to measure this systemic inflammation is with a blood test called high-sensitivity C-reactive protein (hs-CRP). Levels below 1 mg/L indicate low cardiovascular risk, 1 to 3 mg/L indicate intermediate risk, and levels above 3 mg/L signal high risk.
Chronic low-grade inflammation doesn’t just help plaque form. It makes existing plaque more dangerous by thinning the fibrous cap that holds it together, increasing the chance of rupture. This is why someone with moderate plaque buildup but high inflammation can be at greater risk than someone with more plaque but less inflammation.
Air Pollution
Fine particulate matter (PM2.5), the tiny particles produced by vehicle exhaust, industrial emissions, and wildfires, is an increasingly recognized cause of cardiovascular disease. These particles are small enough to pass through the lungs’ protective lining and enter the bloodstream directly. Once in circulation, they trigger oxidative stress, likely through the release of mitochondrial DNA and the generation of reactive oxygen species. Researchers consider oxidative stress the common denominator linking PM2.5 exposure to its various vascular effects, including endothelial damage, increased inflammation, and accelerated atherosclerosis.
People living in areas with high air pollution levels face elevated rates of heart attack, stroke, and heart failure, even after accounting for other risk factors. This means cardiovascular disease isn’t purely a matter of personal choices. Environmental exposures contribute meaningfully, and they disproportionately affect people in urban areas and lower-income communities with less ability to control their exposure.