Despite some reduction in recent decades, cardiovascular disease continues to be the most common cause of death, accounting for up to 50% of deaths in developed countries. Incidence and mortality strongly increase with age. In the following, the epidemiology of three major clinical manifestations of cardiovascular disease, coronary heart disease, stroke and heart failure (which to a large extent have common etiologies), will be addressed.
Despite a major decline in mortality by more than 50% in the second half of the 20th century, coronary heart disease (CHD) remains the single largest killer, accounting for 20% of all deaths in developed countries such as the United States, where mean age of manifestation of a first heart attack is 65-70 years (American Heart Association, 2005). The major risk factors for CHD, which include hypertension, hyperlipidemia, smoking and diabetes, are well established, and 80-90% of all CHD patients have prior exposure to at least one of these risk factors (Khot et al., 2003). In the United States, about 700,000 patients have a new heart attack each year. In recent years, the proportion of affected people surviving the acute stage of a heart attack has substantially increased, but the survivors have a risk of another heart attack, stroke and heart failure that is substantially higher than that of the general population (Hurst, 2002). Although there is evidence that much of the subsequent disease burden could be prevented by cardiac rehabilitation, this opportunity appears to be largely underused. For example, only a minority (32%) of patients aged 70 or older participate in cardiac rehabilitation in the United States (Witt et al., 2004).
Although stroke also accounts for a large share of mortality in developed countries (e.g., about 160,000 deaths annually in the United States [American Heart Association, 2005]), it has an even larger impact as a disabling disease, accounting for a large share of disability among the elderly. For example, in Germany, stroke is responsible for about 15 percent of cases of dependency on permanent nursing care (Ramroth et al., 2005). Mortality has been declining worldwide in the last decades (American Heart Association, 2005), mainly due to improved clinical management, whereas trends for incidence have been less consistent. International comparative studies have found major variation of incidence between countries. For example, within Europe, incidence was found to be threefold higher in some populations from Northern Europe than in populations from middle and Southern Europe (Thorvaldsen et al., 1995). Incidence rates are higher for men than for women, but women generally have a higher stroke prevalence, because they have a longer life expectancy and are more likely to survive a stroke (Sacco, 1997).
Regarding etiology and risk factors, three major types of stroke have to be distinguished: ischemic stroke (IS), intracerebral hemorrhage (ICH), and sub-arachnoid hemorrhage (SAH), accounting for about 88%, 9%, and 3% of all strokes, respectively (American Heart Association, 2005). Major modifiable risk factors for IS identified in large-scale epidemiologic case-control and cohort studies include hypertension, diabetes, lack of physical activity, smoking and coronary artery disease (Boden-Albala and Sacco, 2004). Hypertension is clearly the most important modifiable risk factor for IS, but other factors, including heavy alcohol consumption, anticoagulant therapy and potentially low cholesterol levels may also play a role. For SAH, smoking appears to be a particularly strong risk factor (Longstreth et al., 1992).
Whereas age-adjusted death rates of coronary heart disease and stroke decreased within the past decades, there have been significant increases in the prevalence of chronic heart failure (HF) as well as in associated morbidity and mortality. The lifetime risk of developing HF is now 1 in 5 for both men and women, and it is considerably higher among victims of a myocardial infarction. The prevalence of HF strongly increases with age, and 50% of patients are older than 65 years. Mortality is as high as 50% in 24 months in symptomatic men. In the United States, HF has become the most common hospital discharge diagnosis in patients >65 years of age and the primary cause of readmission within 60 days of discharge (Young, 2004; American Heart Association, 2005). Major risk factors include hypertension, coronary heart disease, diabetes and overweight. With the rise of the diabetes and overweight epidemic in many countries, the burden of disease is expected to rise further in the years to come in many countries.
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