Managing established coronary heart disease

General practice is ideally placed to provide coordinated preventive care

The Department of Health's controversial banding system for promoting health in primary care was discontinued at the end of September 1996. Under the new arrangements for health promotion each practice has the opportunity to plan and develop its own effective health promotion strategy, based on the Health of the Nation and the needs of the practice's population.

In any new strategy for promoting health, priority should go to implementing preventive measures in patients with established coronary heart disease, such as a history of myocardial infarction or stable angina or having undergone revascularisation by angioplasty or coronary artery bypass grafting. This view has been echoed by two recent reports on preventing coronary heart disease in primary care.1 2 The reasons are threefold.

Firstly, patients with established coronary heart disease are at increased risk of subsequent vascular events (death, myocardial infarction, and stroke). In the British regional heart study 14% of 242 men with electrocardiographic signs of definite myocardial infarction had reinfarctions over the 4.2 year follow up, compared with only 2% of those with normal electrocardiograms.3

Secondly, these high risk patients amount to some two to three million people in Britain, and it has been estimated that about half of all deaths from coronary heart disease occur in this population.4 Therefore, preventive measures which reduced mortality would have a considerable impact on the total number of deaths from coronary heart disease.

Thirdly, there is good evidence that a substantial proportion of these high risk patients remain unrecognised in practice and that those who are being treated are receiving suboptimal care, especially women.5 6

The risk these patients face can be substantially reduced by effective management focusing on appropriate changes in lifestyle and pharmacotherapy. Changes in lifestyle include stopping smoking, rehabilitation with exercise, and dietary modification. Observational studies have shown that mortality in patients who stop smoking after myocardial infarction is 50% lower over a two year follow up compared with those who continue to smoke.7

Evaluating cardiac rehabilitation programmes is difficult because of the various combinations of exercise training, modifications of lifestyle, and multiple endpoints used in individual trials. However, an overview of 22 randomised trials of cardiac rehabilitation programmes with exercise involving 4554 patients has confirmed that, after an average of three years' follow up, the risk of cardiovascular mortality was reduced by 22%, fatal reinfarction by 25%, and total mortality by 20%.8 The diet and reinfarction study, involving about 2000 men with a history of myocardial infarction, showed that those who substituted a portion of oily fish into two or three meals each week had a 29% reduction all cause mortality over two years even though their plasma cholesterol concentrations were unchanged.9 These interventions have been less studied in patients with stable angina and those who have undergone revascularisation, but it seems appropriate to extend the findings to these groups.

Pharmacological interventions that have been tested in patients with a history of myocardial infarction include antiplatelet therapy, ß blockade, angiotensin converting enzyme inhibitors, and lipid lowering drugs. Eleven randomised trials have tested the effectiveness of antiplatelet therapy in about 20 000 patients with a history of myocardial infarction. The trials concluded that antiplatelet therapy prevents about 40 vascular events per 1000 patients treated in the first two years after a myocardial infarction irrespective of age, sex, blood pressure, and diabetes.10 Furthermore, other trials have shown that the benefit of antiplatelet therapy can be extended to patients with angina and those who have undergone revascularisation procedures.10 11

The pooled evidence from 23 randomised trials of long term treatment with ß blockers in over 19 000 patients after myocardial infarction suggests that mortality is reduced by about 20%. Additional long term benefits include reducing the risk of reinfarction by 25% and reducing the risk of sudden death by 30%.12

In patients with left ventricular dysfunction after myocardial infarction, angiotensin converting enzyme inhibitors reduced the risk of all cause mortality by 19%, the risk of non-fatal and fatal vascular events by 21%, and the development of severe heart failure by 37% over 42 months of follow up.13 In patients with clinical evidence of heart failure after myocardial infarction, treatment with an angiotensin converting enzyme inhibitor over 15 months resulted in a significant 27% reduction in risk of death and a 19% reduction in vascular events.14

The Scandinavian simvastatin survival study of patients with angina or a history of myocardial infarction clearly showed, in patients with a total cholesterol concentration of 5.5-8.0 mmol/l, a 30% reduction in total mortality and a 42% reduction in coronary mortality over a five year follow up.15 These reductions in mortality were achieved without an increase in non-cardiovascular deaths. Furthermore, the recently published cholesterol and recurrent events trial (CARE) demonstrated that the benefit of cholesterol lowering with pravastatin after myocardial infarctions in patients in whom the total cholesterol was less than 6.2 mmol/l.16

General practice faces a formidable task in implementing the tested interventions in everyday clinical practice. A practice of 10 000 patients will have between 300 and 500 patients with established coronary heart disease, of whom 150 will be aged over 70-75.17 Organising care for this number of patients requires effective teamwork—to identify patients with established coronary heart disease; develop agreed practical, evidence based guidelines; and identify possible barriers to their implementation. The guidelines should include details on assessing risk factors for coronary heart disease, giving appropriate advice about lifestyle and instituting treatment, follow up, criteria for referral, and audit. Improving communication and coordination between primary and secondary care may help to ensure that the results of the clinical trials are implemented in practice.

General practice is uniquely placed for delivering effective care for patients with established coronary heart disease, which could result in many more patients receiving better quality care and enjoying better health.