Medicine is still an inexact science: “A doctor’s care is not a protective bubble, and cardiology is not the exact science that many people wish it to be. A person’s risk of a heart attack can only be estimated, and although drugs, diet and exercise may lower that risk, they cannot eliminate it entirely. True, the death rate from heart disease has declined, but it is still the leading cause of death in the United States, killing 650,000 people a year. About 300,000 die suddenly, and about half, like Mr. Russert, have no symptoms.”