Cardiovascular diseases are the leading cause of death worldwide, according to the World Health Organization. Approximately 17.9 million people died from cardiovascular disease in 2019, and 85% of those deaths were caused by heart attack or stroke. Cardiovascular diseases are a group of disorders that affect the heart and blood vessels. They may affect the blood vessels supplying blood to the heart, brain, and limbs. They may also cause blood clots in the body or simply be damaging to the heart muscle, heart valves, or structure of the heart.