Ischaemic heart disease is a major cause of death and ill health. In 1992 there were 145,000 deaths from ischaemic heart disease in England and Wales, and 22,000 of these deaths occurred in people aged less than 65 years.
In the former Northern Region in 1992 there were 5,634 deaths in men and 4,766 deaths in women. Of these 1,416 (25%) of the men and 426 (9%) of the women died before the age of 65. The commonest cause of years of life lost before the age of 75 in the Northern Region, in both men and women, is coronary artery disease.
Mortality rates vary between countries with Europe and North America having much higher rates than Asia and Africa. The United Kingdom (UK), Eastern Europe and Scandinavia have the highest rates. In England, districts in the North have markedly higher rates. The former Northern Region has the highest rates in England with about 3,000 "excess" deaths each year over the Oxford or Thames Regions. Within districts, manual workers, the unemployed and people from southern Asia have a higher incidence.
Ischaemic heart disease accounts for approximately 4% of hospital admissions and 4% of beds used, with about 400 discharges per 100,000 population admitted to hospital each year. Estimates of the prevalence of coronary heart disease in surveys of populations have produced figures of angina in about 4% of men and women and a possible previous myocardial infarction in 6 -10% of men and 5% of women, all aged 40-59 years.
A general practitioner caring for 2,000 patients can expect to have about 34 patients consulting with ischaemic heart disease per year; 23 of these will have angina. Much of their care will be provided by the primary health care team without referral to hospital.
The amount of ischaemic heart disease in the population is related to a number of factors. Fixed factors are increasing age, male gender, family history of ischaemic heart disease, diabetes, and ethnic origin. Variable factors are smoking, raised blood cholesterol, high blood pressure, obesity, lack of exercise, and psychosocial factors. The incidence of ischaemic heart disease may be lowered by reducing the variable risk factors in both the general population and in individuals at higher risk.
Although the mortality rate from ischaemic heart disease is high in the UK the rate is beginning to fall, especially in younger people. In the USA the decline began in the 1960s and mortality has fallen by about a third since then. This decline has been attributed to a combination of lifestyle changes, medical treatment, and revascularisation procedures (coronary artery bypass grafting and angioplasty). Other unidentified factors are also operating and the decline in mortality rates in the USA began before there were appreciable changes in lifestyle and treatment. It has been suggested that the decline in mortality rate is due to a combination of a fall in incidence together with a reduced case fatality rate. The different rates between areas and the decline in rates over time gives some cause for long-term optimism as it suggests that prevention and treatment measures will have an impact, not only in reducing symptoms but also reducing death rate. However, the changing age structure of the population in the UK means that there will be an increase in the number of "cases" unless there is a very dramatic fall in incidence.
In their recent editorial in the New England Journal of Medicine, Hillis and Rutherford (1994) compared and contrasted the relative merits of medical therapy, coronary artery bypass grafting and balloon angioplasty. Having stated that "coronary artery bypass grafting is, in skilled hands, safe and highly effective in relieving angina" and that balloon angioplasty "is a safe, relatively non traumatic, and highly effective procedure for relieving angina, improving exercise performance and reducing the need for anti-anginal medications", they concluded by summarising their view of the current position of these two procedures compared with medical treatment.
"At present what are reasonable guidelines for treating patients with symptomatic coronary artery disease? Lest we forget, medical therapy relieves angina in many patients regardless of the severity of disease, and its influence on survival is similar to that of surgery in patients with single-vessel coronary artery disease or multi-vessel coronary artery disease (not involving the proximal left anterior descending artery) with normal left ventricular systolic function (Yusuf et al., 1994). For the patient with disease of the left main coronary artery, multi-vessel disease involving the proximal left anterior descending artery, or three-vessel disease and impaired left ventricular systolic performance, surgery is indicated because it improves survival.
For patients with single-vessel or multi-vessel disease (not involving the proximal left anterior descending artery) and normal left ventricular systolic function, the choice of medical therapy, angioplasty, or bypass grafting can be individualised. If non-medical therapy is chosen, the decision whether to use angioplasty or bypass grafting should be reached with the understanding that surgery is associated with greater initial morbidity but results in more effective relief of angina and in freedom from repeated procedures in the next two or three years. On the other hand, angioplasty is associated with lower rate of initial morbidity but a greater likelihood of recurrent angina, with the need for anti-anginal medications or subsequent re-vascularization procedures."
Yusuf, S., Zucker, D., Peduzzi, P., Fisher, L.D., Takaro, T., Kennedy, J.W., Davis, K., Killip, T., Passamani, E., Norris, R. et al., (1994) Effect of coronary artery bypass graft surgery on survival: overview of 10-year results from randomised trials by the Coronary Artery Bypass Graft Surgery Trialists Collaboration. Lancet 344:563-70.