Diet and the prevention of coronary heart disease

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Active prevention of coronary heart disease (CHD) is usually started immediately after its first clinical manifestation. Secondary prevention focuses on risk reduction in people with established CHD who are at high risk of recurrent cardiac events and death. It is important to remember that the two main causes of death in these patients are sudden cardiac death (SCD) and heart failure (HF), often resulting from myocardial ischaemia and subsequent necrosis. The main mechanism underlying recurrent cardiac events is myocardial ischaemia resulting from atherosclerotic plaque rupture or ulceration. Plaque rupture is usually the consequence of intraplaque inflammation combined with a high lipid content of the lesion, high concentration of leucocytes and lipid peroxidation products.

Thus, in patients with established CHD, the main aims of the preventive strategy are to prevent malignant ventricular arrhythmia and the development of severe ventricular dysfunction (and heart failure) and to minimise the risk of plaque inflammation and ulceration. This means that the priority of secondary prevention is somewhat different from that of primary prevention. In the context of primary prevention, intervention focuses on traditional risk factors (e.g. blood cholesterol or blood pressure) and surrogate endpoints rather than on specific clinical complications such as SCD. This does not mean that traditional risk factors of CHD should not be measured and, if necessary, corrected in secondary prevention, because they also play a role in the occurrence of CHD complications. It simply means that because complications such as SCD and associated syndromes are often unpredictable, occur out of hospital and far from any potential therapeutic resources in the majority of cases, and account for about 50 per cent of cardiac mortality in secondary prevention, they should be the priority of any secondary prevention programme. For that reason, in the present text, we will focus our dietary recommendations and comments specifically on clinical efficacy and not on surrogate efficacy.

Whatever the specific clinical aims of the programme, nutritional evaluation and counselling of each individual with CHD must be a key point of the preventive intervention. Nutrition is, however, only one component of such a programme. Exercise training, behavioural interventions (particularly to help the patient abstain from smoking) and drug therapy have equally important roles. The control of risk factors has been seen traditionally in the perspective of prevention. The dietary prevention programme is commonly initiated during hospitalisation for a first CHD event. With the shortening of stay in the coronary care unit (CCU), dietary intervention is initiated during the following days at hospital, then continued in secondary prevention centres and included in cardiac rehabilitation programmes. An individual dietary prevention programme should be developed under the guidance of a specialised dietician and in close collaboration with the patient’s cardiologist and primary care physician, so that there is no discontinuity or discrepancy in dietary counselling between the hospitalisation and post-hospitalisation phases of the rehabilitation programme.