Before 1900, infectious diseases and malnutrition were the most common causes of death. However, as robust economies developed, the common causes of death in these economies shifted to cardiovascular diseases and cancer. This shift was largely due to improved nutrition and public health measures. At the same time, easier access to less expensive foods with a higher fat content has led to an increase in total caloric intake and continued mechanization has resulted in a lower daily caloric expenditure. This combination has produced a more sedentary lifestyle leading to a higher mean body mass index, blood pressure, serum lipid levels, and blood sugar. In 2000, cardiovascular disease accounted for nearly half of all deaths in developed countries and 25% of the deaths in developing countries. As this trend continues in developing countries, cardiovascular disease will become the dominant cause of death by 2020, accounting for at least one in every three deaths worldwide. By 2020, it is predicted that cardiovascular disease will claim 25 million lives annually and that coronary artery disease (CAD) will surpass infectious disease as the world's number one cause of death and disability.
Because the prevalence of CAD is so high, preventing even a small proportion of cases could save lives, avoid considerable disability, and substantially reduce healthcare expenditures. In addition, measures that prevent CAD may diminish other manifestations of atherosclerosis, such as stroke and peripheral artery disease, and may have a favorable impact on hypertension, diabetes, cancer, cognitive function, depression, and other chronic conditions. Thus, the use of affordable preventive strategies should have high priority in both developed and developing countries.
Efforts to prevent cardiovascular disease are commonly classified into primary or secondary prevention. Primary prevention refers to therapeutic interventions applied to individuals without overt manifestations of disease although individuals may be classified as low- or high-risk individuals. In this circumstance, the goal is to lower the individual's risk of suffering a future cardiovascular event. Secondary prevention refers to therapeutic interventions applied to individuals who have already experienced some clinical manifestation of disease, such as a myocardial infarction. In this circumstance, the goal is to reduce the individual's risk of suffering a second cardiovascular event.
Over the last 50 years, there have been many advances in understanding the pathophysiology of cardiovascular disease and atherosclerosis. As this occurred, several genetic, biochemical, and lifestyle factors associated with an increased risk of cardiovascular disease were identified. Once these so-called 'risk factors' were identified, interventions to modify their effects on the clinical occurrence of cardiovascular disease were developed and tested. Cigarette smoking, hypertension, and lipid abnormalities are causally related to CAD, and the corresponding interventions of smoking cessation, blood pressure management, and lipid reduction are cost-effective in both primary and secondary prevention. Other pharmacological approaches proven to be beneficial and cost-effective include aspirin, beta-blockers, and angiotensin-converting enzyme (ACE) inhibitors in secondary prevention and aspirin in primary prevention. There is little doubt that diabetes, physical inactivity, and obesity increase the risk of CAD, but the magnitude of the effect attributable to intervention upon these factors has been difficult to determine.
Although substantial progress has been made, challenges still remain. As the population ages, the number of individuals with important risk factors for cardiovascular disease will increase, as will the number of individuals living with cardiovascular disease. Obesity and physical inactivity are epidemic among all sectors of the population, including children. This is expected to increase the prevalence of diabetes and hypertension and slow the favorable decreasing trend in mean lipid levels. Thus, in addition to continued research on the mechanistic and epidemiological determinants of cardiovascular disease, there should be continued efforts to promote adherence to existing treatment guidelines for risk factor modification and develop effective risk prevention programs.