Coronary heart disease (CHD), or atherosclerotic CAD, is the number one cause of death in the United States and worldwide. Every minute, an American dies of CHD. About 37% of people who experience an acute coronary event, either angina or MI, will die of it in the same year. Death rates of CHD have declined every year since 1968, with about half of the decline from 1980 to 2000 due to treatments and half due to improved risk factors. CHD is still responsible for approximately one of five deaths and over 600,000 deaths per year in the United States. CHD afflicts nearly 16 million Americans and the prevalence rises steadily with age; thus, the aging of the US population promises to increase the overall burden of CHD.
Most patients with CHD have some identifiable risk factor. These include a positive family history (the younger the onset in a first-degree relative, the greater the risk), male sex, blood lipid abnormalities, diabetes mellitus, hypertension, physical inactivity, abdominal obesity, cigarette smoking, psychosocial factors, and consumption of too few fruits and vegetables and too much alcohol. Many of these risk factors are modifiable. Smoking remains the number one preventable cause of death and illness in the United States. Although smoking rates have declined in the United States in recent decades, 18% of women and 21% of men still smoke. According to the World Health Organization, 1 year after quitting, the risk of CHD decreases by 50%. Various interventions have been shown to increase the likelihood of successful smoking cessation (see Chapter 1-08).
Hypercholesterolemia is an important modifiable risk factor for CHD. Risk increases progressively with higher levels of low-density lipoprotein (LDL) cholesterol and declines with higher levels of high-density lipoprotein (HDL) cholesterol. Composite risk scores, such as the Framingham score (see eTable 28–2) and the 10-year atherosclerotic cardiovascular disease risk calculator (http://my.americanheart.org/cvriskcalculator), provide estimates of the 10-year probability of development of CHD that can guide primary prevention strategies. The 2018 ACC/AHA Guideline on the Treatment of Blood Cholesterol to Reduce Atherosclerotic Cardiovascular Risk in Adults suggests statin therapy in four populations: patients with (1) clinical atherosclerotic disease, (2) LDL cholesterol 190 mg/dL or higher, (3) diabetes who are aged 40–75 years, and (4) an estimated 10-year atherosclotic risk of 7.5% or more aged 40–75 years (Figure 10–5). Importantly, the guidelines do not recommend treating to a target LDL cholesterol. Patients in these categories should be treated with a moderate- or high-intensity statin, with high-intensity statin for the higher-risk populations (Table 10–7). The ACC/AHA atherosclerotic cardiovascular disease risk estimator allows clinicians to determine the 10-year CHD risk to determine treatment decisions (http://tools.acc.org/ascvd-risk-estimator-plus/).
Table 10–7.High-, moderate-, and low-intensity statin therapy (used in the RCTs reviewed by the expert panel).1,2