A large-scale international study has revealed that nearly all heart attacks, strokes, and heart failures—over 99% of cases—are linked to four major, often modifiable, risk factors. The comprehensive research, led by Northwestern Medicine and Yonsei University, analyzed health data from more than 9 million adults in South Korea and thousands in the United States over a decade. The four critical risk factors identified are high blood pressure, high cholesterol, elevated blood sugar levels (or diabetes), and tobacco smoking (past or current). The study found that individuals who experienced a major cardiovascular event almost invariably had at least one of these factors at 'nonoptimal' levels before the event. High blood pressure emerged as the most prevalent risk factor, preceding over 93% of cardiovascular events in both countries studied. These findings challenge the common perception that heart attacks and strokes can strike without any warning or pre-existing conditions. Instead, the study strongly advocates for aggressive screening and management of these risk factors to prevent serious cardiovascular disease. Even among lower-risk demographics, such as women under 60, more than 95% of heart attacks or strokes were still associated with one of these conditions. Experts highlighted that managing these conditions, even below clinical diagnostic thresholds, is crucial for long-term heart health. The study, published in the *Journal of the American College of Cardiology* in late 2025, reinforces the global importance of preventive health measures and lifestyle modifications.