Nearly every heart attack, stroke, and major cardiovascular event can be traced back to the same four health issues—conditions that are common, measurable, and, crucially, treatable.

That’s the central finding of one of the largest cardiovascular studies ever conducted, which analyzed health data from more than 9 million adults in the United States and South Korea. Published in 2025, the research concludes that 99% of serious cardiovascular events are linked to four cardiovascular risk factors: high blood pressure, high cholesterol, high blood sugar, and tobacco use.

For doctors, policymakers, and patients alike, the message is hard to ignore: heart disease is rarely random—and prevention starts earlier than most people think.

What are the four cardiovascular risk factors driving nearly all events?

The study zeroed in on four well-established but often poorly controlled risks. These are not obscure genetic anomalies or rare diseases. They are conditions millions of people live with every day.

1. High blood pressure (hypertension)

Hypertension stood out as the most dominant factor in the analysis.

• More than 93% of people who suffered a heart attack, stroke, or heart failure had elevated blood pressure before the event.
• Even modest increases—levels that sometimes fall just below clinical thresholds—were associated with higher long-term risk.

High blood pressure damages arteries over time, making them stiffer and narrower. That damage creates the perfect environment for clots, heart attacks, and strokes.

2. High cholesterol

Elevated LDL (“bad”) cholesterol contributes to plaque buildup in arteries, a process known as atherosclerosis.

• Plaque restricts blood flow.
• Ruptured plaque can trigger sudden blockages, leading to heart attacks or strokes.

The study suggests cholesterol often works in tandem with hypertension, compounding risk rather than acting alone.

3. High blood sugar (diabetes and prediabetes)

High blood sugar damages blood vessels and nerves, accelerating cardiovascular disease.

Importantly, the researchers found that even blood sugar levels below the diabetes cutoff were associated with increased risk—raising questions about whether current diagnostic thresholds miss early danger.

4. Tobacco use

Smoking remains one of the most potent cardiovascular risk factors.

• It inflames blood vessels.
• It raises blood pressure.
• It reduces oxygen in the blood.

While smoking rates have declined in the U.S., its impact remains severe—and immediate—compared with other risks that accumulate more slowly.

Why does this study matter now?

In recent years, several reports have suggested a growing number of heart attacks were occurring in people with “no risk factors.” This new analysis directly challenges that narrative.

“We think the study shows very convincingly that exposure to one or more nonoptimal risk factors before these cardiovascular outcomes is nearly 100%,” said Dr. Philip Greenland, senior author and professor of cardiology at Northwestern University Feinberg School of Medicine.

The key word is “nonoptimal.” Earlier studies may have missed risk factors that were present—but not yet severe enough to trigger a diagnosis.

In other words, the risk was there. It just wasn’t labeled.

How younger women fit into the picture

One of the most striking findings involves women under 60, a group traditionally considered lower-risk for heart disease.

• Over 95% of cardiovascular events in younger women were still linked to at least one of the four risk factors.
• Many had mild or early-stage hypertension or cholesterol issues that went untreated.

This helps explain why cardiovascular disease remains the leading cause of death among women in the U.S., despite persistent myths that it’s primarily a male problem.

Are heart attacks without risk factors a myth?

Not entirely—but they are exceedingly rare.

The authors argue that most so-called “risk-free” cases fall into one of three categories:

• Undiagnosed hypertension or cholesterol
• Risk factors below clinical cutoffs
• Incomplete medical records

In a related editorial, Dr. Neha Pagidipati, a cardiologist at Duke University who was not involved in the study, emphasized that waiting for risk factors to become “official” diagnoses may be a dangerous mistake.

Early exposure matters, even if numbers don’t yet look alarming.

Why prevention beats treatment every time

Cardiovascular medicine has made remarkable advances in emergency care. Survival rates after heart attacks are higher than ever. But survival is not the same as health.

• Heart failure is often a lifelong condition.
• Stroke survivors may face permanent disability.
• Medical costs accumulate quickly.

This study reinforces a longstanding but often ignored truth: preventing risk factors is far more effective than treating events.

What early prevention actually looks like

Prevention does not require extreme measures. It requires consistency.

• Regular blood pressure checks, starting in early adulthood
• Routine cholesterol and blood sugar screening
• Smoking cessation support that goes beyond advice
• Lifestyle interventions before medication becomes unavoidable

What this means for public health policy

From a policy perspective, the findings suggest that cardiovascular disease is not primarily a mystery—it’s a management failure.

Areas where intervention could make an outsized impact:

• Community blood pressure screening programs
• Lower thresholds for “at-risk” classification
• Insurance coverage for early lifestyle counseling
• Stronger tobacco control measures

Countries that invest in early detection consistently see lower rates of catastrophic heart events later on.

What individuals should take away from the data

The study does not argue that genetics or rare conditions don’t matter. It argues that they matter far less often than we assume.

If you’ve ever been told:

• “Your blood pressure is a little high, but not enough to worry about”
• “Your cholesterol is borderline”
• “You’re not diabetic, just close”

That gray zone is where most cardiovascular damage begins.

TL;DR

• A study of 9 million people found that 99% of heart attacks and strokes are linked to four cardiovascular risk factors
• High blood pressure is the single biggest contributor
• Even “mild” or undiagnosed risk factors significantly raise long-term risk
• Prevention and early management matter more than ever, especially for younger adults and women