Heart Disease Risk: The Rest of the Story
With heart disease as the leading cause of death in the U.S., many Americans are familiar traditional modifiable risk factors for heart disease such as smoking, elevated cholesterol, being overweight, high blood pressure, physical inactivity and diabetes. However over 50% of heart attack victims and 80% of patients with coronary artery disease have normal cholesterol levels. TV commercials focusing on elevated cholesterol as a primary risk factor endlessly repeat “When diet and exercise aren’t enough, ask your doctor if (the featured statin drug) is right for you.
Major factors independent of cholesterol and blood pressure include chronic stress and lack of social supports. One medical study showed that people exposed to 14 years of war in Beirut had significantly more coronary blockages evaluated by angiography (dye injected into heart arteries for an X-ray) than visitors not under this stress independent of other risk factors. Another study found that workers who faced high psychological demands without having much control over their day to day decisions had three times the risk of high blood pressure and these workers all had thickened or enlarged hearts.
Stress will cause the formation of coronary artery blockages even on a diet lower in fat and cholesterol. On a higher fat diet the influence of stress on coronary blockages was increased thirty times. Stress chemicals also increase the permeability of the artery walls to cholesterol i.e. cholesterol is more easily absorbed into the lining of the wall. Chronic stress also decreased HDL, the “good” cholesterol.
The lining of arteries normally produces a substance called nitric oxide (NO). It helps to dilate all arteries including coronary. As the process of atherosclerosis progresses all arteries are less able to produce NO. As a result, arteries become hyper-responsive to stress and the same amount of stress chemicals cause partially blocked arteries to constrict even more than normal ones. The more blocked the artery is the more likely it will go into spasm at the site of the blockage when stress chemicals are released. Exercise normally produces an increase in NO to dilate blood vessels. However in people who have coronary blockages, exercise will cause their blood vessels to constrict since they are less able to release NO. Smoking also causes decreases production of NO.
The protective effects of social support in decreasing cardiovascular risk are well documented. The Pennsylvania community of Roseto, settled in the 1890′s by Italian immigrants, had prior to the early 1960′s, a near zero cardiac mortality rate for men age 55-64 (a high risk age group in the rest of the U.S.) and a death rate from heart attacks of 10 per 1000 for over age 65, half the national average. This was curious because in the communities just a few miles away populated predominantly by white Anglo-Saxon Protestants, the rates of cardiac mortality corresponded with the rest of the country. Over the past 50 years “the Roseto effect” has been studied extensively by medical and sociological researchers as to why this close knit Italian community who had all the traditional risk factors for heart disease such as being overweight, diabetes, smoking and high fat diet would have such low rates of heart disease. During the decades of the 1960′s and 1970′s the close social ties began to dissolve as children moved away and the social support and customs brought from the old country disappeared. As these changes occurred, the death rates from heart disease rose to the level of the rest of the country. The researchers concluded ” Those with the conventional risk factors are more likely to develop myocardial infarction than those without risk factors, but an even larger proportion of the population may have the risk factors and not succumb to myocardial infarction over a period of nearly three decades” (if they are protected by a strong sense of connection and community). A similar protective effect of strong social connections and a sense of belonging has been demonstrated in other studies elsewhere in the U.S. and abroad.
When at least 50% of the risk of heart attacks and heart disease cannot be solved or explained by modifying traditional risk factors or statin drugs it is time to include some new risk factors such as chronic stress and lack of social supports.