Declining cardiovascular disease incidence and environmental components

After rising for many years in the mid-to-late 1930s the mortality from ischaemic heart disease (IHD) began to decline in many countries. This represents a decline in both out-of-hospital (community) and hospital deaths. Non-fatal myocardial infarction (MI) has also declined. A literature review was conducted to examine lifestyle and environmental factors contributing to the decline. Half of the decline is attributable to changes in lifestyle and in the known major risk factors. Changes in nutrition appear relevant to the decline, in particular an increased ratio of polyunsaturated to saturated fat intake and a reduced saturated fat intake overall. There is little evidence to support a role of changing alcohol consumption, changing coffee consumption, changing exercise levels or reduction in excess weight in the declining incidence of IHD. While the benefit of smoking cessation is a clear one, its impact on the differing trends in various countries is not clear. Socio-economic factors appear to influence the rate and extent of decline in IHD in different groups and may help explain some of the regional differences in IHD incidence. Reductions in blood pressure within the 'normal range' which may occur with lifestyle changes may also be an important contributor.