Heart failure: how can we prevent the epidemic?

The issue of preventing heart failure, or preventing cardiovascular disease in general, brings into focus differences between public health and medical approaches to disease prevention. Whereas a public health approach to prevention might be based on environmental changes, legislation, and education about healthy lifestyles, the medical approach is based on absolute risk assessment for the individual patient.15 Guidelines for preventing heart failure published by the National Heart Foundation of Australia and the Cardiac Society of Australia and New Zealand16 recommend correction of reversible causes of cardiac disease and treatment of coronary risk factors, especially smoking, hypertension, dyslipidaemia and diabetes. The guidelines also recommend lifestyle interventions to reduce absolute cardiovascular risk, including smoking cessation, healthy eating, weight reduction, regular physical activity, and moderation of alcohol and salt intake.

Medical approach. For prevention in people who have yet to manifest cardiovascular disease, Tonkin et al advocate greater emphasis on absolute risk estimation to optimise health gains and produce more cost-effective treatment and prevention.15 Calculations of absolute risk are based on Framingham risk scores for age, sex, cigarette smoking status, diabetes status, blood pressure, and levels of total and high-density lipoprotein cholesterol.17 The Australian guidelines define “higher risk” as a calculated 5-year cardiovascular disease risk threshold exceeding 10%–15% and recommend that patients at greater risk may require drug treatment.15,18 Tonkin et al argue that linking estimates of the likely absolute benefit of interventions with calculation of absolute risk should reinforce the rationale for lifestyle measures for all individuals and pharmacological treatment for those at high risk.15

The absolute risk model has several limitations as a preventive strategy. Firstly, the model fails to take account of the lifelong evolution of cardiovascular disease. Secondly, it presents a paradox, because the risk threshold for intervention requires cardiovascular disease to have already progressed to an extent sufficient to significantly increase the 5-year risk of cardiovascular events. Yet most cardiovascular events occur in people whose 5-year risk is less than 10%–15%, simply because the number of people at lower risk is far greater.9 Thirdly, the absolute risk model provides no guidance for longer-term prevention strategies at a community level, particularly in young people.

The absolute risk model is also impractical as a prevention strategy. Many people with risk factors for heart failure and other cardiovascular disease avoid doctors. Even for those who do attend, the medical profession is currently failing to adequately implement prevention and treatment strategies. The CASE study showed that, even in the hands of an “interested” cohort of GPs, angiotensin-converting enzyme inhibitors were used in little more than half of the patients diagnosed with heart failure.5 Furthermore, a recent Victorian study of patients with coronary heart disease19 showed that many patients were not achieving their risk-factor targets: plasma total cholesterol level was > 4.0 mmol/L in 74% and > 4.5 mmol/L in 54% of patients; 40% of patients had blood pressure > 140/90; 8% had unrecognised diabetes; 75% were overweight (body mass index > 25 kg/m2); 15% were smokers; 26% were not walking regularly for exercise; and 29% were consuming more than two alcoholic drinks daily.

A similar failure to reduce risk-factor prevalence was reported by the Second Australian National Blood Pressure Study,20 in which 38% of subjects with hypertension were previously untreated and only a third of subjects with hypercholesterolaemia were receiving lipid-lowering drugs. Moreover, once enrolled in the study, about half the participants failed to achieve a treatment target blood pressure of < 140/90 mmHg, despite their participation in a clinical trial, in which GPs might be expected to be more likely to try to achieve treatment targets.

Public health approach. Lifestyle modification (including changes in diet, increased exercise, quitting smoking, stress reduction) offers considerable potential for prevention of cardiovascular disease. A diet rich in fruits, vegetables and low-fat dairy foods and with reduced saturated fat and total fat content substantially lowers blood pressure — the reduction is greater in people with hypertension than in those with normal blood pressure, and further reduction is seen when sodium intake is reduced below 100 mmol/day.21,22 More-over, lifestyle modification is more effective than drug therapy for preventing diabetes in people with impaired glucose tolerance.23,24 The combination of lifestyle changes with usual-care cholesterol-lowering therapy produces greater reduction of coronary events in people with coronary artery disease than cholesterol-lowering therapy alone.25 However, strategies based on lifestyle modification have yet to be generally applied, and longer-term studies are required to determine whether they reduce the incidence of heart failure and cardiovascular disease.

From a public health perspective, legislation has played an essential role in reducing tobacco smoking. State governments are starting to address the obesity epidemic, and schools are encouraging students to exercise more. The National Heart Foundation of Australia and other organisations are working to promote a healthy lifestyle, but the increasing prevalence of heart failure and overweight and obesity indicates an urgent need for more effective prevention strategies.

Cardiovascular disease begins early in life in association with traditional risk factors for coronary heart disease. Behavioural and lifestyle patterns learned in childhood tend to continue into adulthood and are largely the same factors that predict cardiovascular events later in life.26 Obesity and overweight in Australian children are strong predictors of adult weight from the age of 6 years.27

The doubling of obesity prevalence in the past 20 years can be described as a normal response to a “pathological” environment. There is an excess of available food and active encouragement (by advertisers and food outlets) to consume more salty, high-energy food than is required. The increased availability and active promotion of labour-saving technology and sedentary leisure activities (eg, television viewing, computer games), together with sedentary occupations, provide disincentives to engaging in physical activity.28

In the face of these environmental influences, strategies reliant on individual behaviour modification to reduce risk factors have little chance of long-term success. A multitiered approach to preventing heart failure and other cardiovascular diseases is likely to yield the greatest impact — one that encompasses environmental determinants of lifestyle, including urban planning, changing the nature of work to promote physical activity, legislation, and education about healthy lifestyles throughout life, in addition to aggressive control of risk factors in high-risk individuals (Box).7,29

Legislation played an essential role in raising community awareness of the harmful effects of tobacco products, and could play a similar role in the public health strategy to prevent heart failure and other cardiovascular disease. Laws could be introduced to restrict advertising of high-energy fast foods, snacks, and confectionery, particularly advertising directed at children. Legislation could also ensure that all restaurants and food outlets provide a range of fresh fruit and vegetables as part of their menu. McDonald’s recently moved in this direction by introducing apples and side salads as an alternative to potato chips (“fries”) and Coke with their burgers.30 Food outlets could use their imagination to provide children with an inviting range of fruit and vegetables. Indeed, they could turn the requirement to provide fruit and vegetables to their advantage by reducing the size of servings of fries and offering free fresh fruit and a low-kilojoule drink with each burger or meal.

GPs have an important role to play in preventive healthcare, by screening for, identifying and treating risk factors, and through education about strategies to prevent ill health. Practice nurses can greatly assist in this task by helping patients achieve treatment targets.31 In a recent UK study, brief individual counselling by practice nurses in primary care elicited sustained increases in fruit and vegetable consumption.32 Practice nurses could also educate patients in managing their risk factors. A Victorian study in which patients were coached by a dietitian on how to reduce cholesterol levels showed that coaching at 6-week intervals (by telephone) produced a reduction in plasma cholesterol levels equal to that produced by lipid-lowering drugs.33 Practice nurses could assist people who require treatment for hypertension or a raised plasma cholesterol level to monitor these factors, know their treatment targets, and work with their GP to achieve these targets.