Risk Factors
Nearly 5 million Americans currently suffer from heart failure. About 550,000 new cases of heart failure are now diagnosed each year. In 1970 there were only 250,000 new cases, so the annual numbers have risen dramatically. Such numbers represent an increasingly older population. Although there has been a dramatic increase over the last several decades in the number of people who suffer from heart failure, survival rates have been improving greatly. Of note, older men tend to fare better than older women.
Coronary artery disease and high blood pressure are the main causes of heart failure. Other diseases that damage or weaken the heart muscle or heart valves can also cause heart failure. Heart failure is most common in people over age 65, African Americans, and women.
Advancing Age
Heart failure is the most common reason for hospitalization in the elderly, and as the population ages, the incidence of heart failure is rising dramatically. According to one report, it occurs at a rate of about 10 per 1,000 people after age 65. The positive implication is, however, that people are living longer with heart failure.
Gender
Men are at higher risk for heart failure than women, although the difference narrows with age. Women also have a better survival rate than men do when heart failure is caused by valvular heart disease, high blood pressure, or alcohol abuse. (Some studies indicate that this is because men may be more susceptible to the process of heart muscle-cell remodeling, a damaging effect of hypertension.)
The survival rates of women and men are more similar, however, when heart failure evolves from coronary artery disease or heart attack. Women are much more likely to develop heart failure after a heart attack than men. In such cases, some evidence suggests that the reasons for this may include less aggressive approach to treatment for the initial heart conditions.
Ethnicity
African-Americans are at higher risk for heart failure than Caucasians, and studies have reported that they tend to do much worse. In a 2003 study, however, in which Caucasians and African-Americans had comparable treatment, African-Americans actually had lower 1-year mortality rates (with slightly higher rates of rehospitalizations). Still, more studies are needed to determine if there are actual biologic differences in specific patients. Some evidence, for example, suggests that African-Americans are more often likely than Caucasians to develop diastolic heart failure (a failure of the heart muscle to relax normally), which is often a precursor to systolic heart failure (impaired ability to pump blood). Caucasians tend to develop systolic heart failure first. In one study comparing Caucasian and African-Americans who only had diastolic heart failure, African-Americans had a 30% higher mortality rate.
Family History and Genetics
A family history of early heart failure caused by cardiomyopathies (diseases that damage the heart muscle) may predispose people to the disease. Researchers are also looking for changes in specific genes that might regulate systems involved in heart failure and so increase susceptibility in certain populations.
Chronic Alcohol Abuse
Chronic alcohol abuse can damage the heart muscles, can cause hypertension, and may prove to be one cause of idiopathic dilated cardiomyopathy. Moderate alcohol consumption, on the other hand (generally defined as two drinks a day for men and one for women), may protect against heart failure. Non-drinkers, though, are not advised to begin drinking.
Medical Conditions that Increase the Risk for Heart Failure
- Coronary artery disease. More than 60% of the cases of heart failure in the United States may be due to coronary artery disease and its risk factors (smoking, sedentary living, obesity).
- Heart attack. The injured heart after an attack is at high risk for failure. Therefore, the improved survival rates from heart attack over the past decades have actually been responsible for the dramatic increase in heart failure rates.
- High blood pressure. Hypertension is a significant risk factor and is present in 75% of patients with heart failure. (One study suggested that people with hypertension who suffer from depression are at particular risk for heart failure, possibly because depression affects the nervous system involved in regulating the heart.)
- Diabetes. People with diabetes are at high risk for heart failure, particularly if they also have coronary artery disease. Even blood sugar abnormalities that precede diabetes increase the risk.
- Obesity. Obesity is associated with both hypertension and type 2 diabetes, conditions that place people at risk for heart failure. New evidence strongly suggests that obesity itself is a major risk factor for heart failure, particularly in women. In a major 2002 study, about 14% of heart failure cases in women and 11% in men could be attributed to obesity. Both overweight and obese women had a significantly higher than normal risk for heart failure. Only obesity led to a significant risk in men.
- Valvular heart disease. Specific valvular conditions that are common in patients with heart failure include aortic stenosis and mitral regurgitation.
- Severe emphysema. This chronic lung disease is a major risk factor for right-side heart failure.
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