Heart attacks and strokes are often talked about like lightning strikes, sudden and unpredictable. A large new analysis challenges that idea, arguing that most serious cardiovascular events are preceded by familiar red flags. Researchers examining long term health data found that nearly everyone who went on to have a heart attack or stroke had already shown at least one major risk factor beforehand. They described these as early signs that trouble may be building even when a person feels fine.
The study, published in the Journal of the American College of Cardiology, compared participant data from South Korea and the United States to see whether warning patterns were consistently present. The team focused on four broad categories that doctors have tracked for decades. Those were elevated blood pressure, unhealthy cholesterol levels, higher than normal blood sugar, and tobacco use. When the researchers looked at these factors together, they reported they appeared before almost all of the cardiovascular cases analyzed.
High blood pressure stood out as the most common signal, in part because it can quietly damage blood vessels for years. Many people have no symptoms, so they do not realize anything is wrong until a complication occurs. The study reported that about 93 percent of participants had hypertension before experiencing a heart attack or stroke. Common influences include age, family history, body weight, diet, alcohol intake, stress levels, and other individual factors that can push blood pressure upward over time.
Cholesterol was another major piece of the picture, and it can also rise without obvious warning signs. When cholesterol levels are elevated, fatty material can accumulate in arteries, narrowing blood flow and increasing the chance of a clot or blockage. Diet, inactivity, age, and genetics all play a role, and the problem is usually discovered through routine blood work. The key point from the analysis was not that cholesterol is the only driver, but that it frequently travels alongside other risks that compound the strain on the cardiovascular system.
Blood sugar was the third factor, and the researchers linked higher glucose readings to prediabetes and diabetes patterns that often develop gradually. Elevated blood sugar is typically confirmed through laboratory testing, not by how a person feels on a random afternoon. Some people do notice symptoms such as increased thirst, frequent urination, blurry vision, or unexplained weight loss, but many do not. Over time, higher glucose can harm blood vessels and nerves, adding to the conditions that make strokes and heart attacks more likely.
The fourth factor was smoking, including past or current tobacco use. Smoking is associated with faster heart rate, higher blood pressure, and damage to the lining of blood vessels, which encourages narrowing and blockage. Even when someone quits, a history of tobacco exposure can remain part of their risk profile for years. In the analysis, the researchers emphasized that the combined presence of these risks was overwhelming across cases, with the four factors together showing up before 99 percent of cardiovascular events.
Philip Greenland, a cardiologist at Northwestern University and the study’s senior author, framed the results as a wake up call for prevention. “We think the study shows very convincingly that exposure to one or more nonoptimal risk factors before these cardiovascular outcomes is nearly 100 percent,” he said. Greenland also argued that the next step is not hunting for exotic explanations when the familiar ones are right in front of us. “The goal now is to work harder on finding ways to control these modifiable risk factors rather than to get off track in pursuing other factors that are not easily treatable and not causal.”
One reason these findings land so hard is that all four categories are measurable well before an emergency happens. Blood pressure can be checked in minutes, cholesterol and glucose can be tracked through standard blood tests, and smoking status is a straightforward question with real consequences. The study’s message is not that every event is perfectly preventable, but that the vast majority of cases appear to leave footprints. In other words, what feels sudden at the end may have been building quietly for a long time.
For readers, it helps to understand what these terms mean in everyday life. A heart attack usually happens when blood flow to part of the heart is blocked, often by a clot forming on top of plaque in a coronary artery. A stroke commonly occurs when blood flow to part of the brain is interrupted, either by a blockage or by bleeding from a ruptured vessel. High blood pressure can speed up damage to vessel walls, and high LDL cholesterol can contribute to plaque formation, a process known as atherosclerosis. Elevated blood sugar can worsen inflammation and vessel injury, while smoking accelerates many of these same pathways and reduces the oxygen carrying efficiency of blood.
Because these risks often cluster, many doctors look at them together rather than in isolation. Lifestyle steps like regular physical activity, a diet rich in whole foods, and smoking cessation are frequently recommended foundations, while medications may be used when numbers stay above healthy ranges. Screening matters because hypertension and high cholesterol can be silent, and “borderline” readings may still signal that the body is drifting in the wrong direction. If you have thoughts on why so many people miss these early signals, share your perspective in the comments.
