ACE Inhibitors in the treatment of chronic heart failure: Effective and cost-effective
|Chronic heart failure (CHF) is the syndrome of breathlessness, fatigue and fluid retention resulting in an impaired ability of the heart to pump properly. The commonest causes are coronary heart disease (CHD) and primary heart muscle diseases (cardiomyopathies), with heart valve disease less common. Heart failure is over-diagnosed (especially in the elderly) and is best confirmed using cardiac ultrasound . Only a minority of people in the community with suspected CHF receive this investigation .
The size of the problemThe size of the CHF problem in a health authority with a population of 250,000 and based on a prevalence of 1% [3,4] is shown below:-
|CHF is a serious condition with mortality ranging from 50% over 5 years in mild heart failure  to 60% per year in severe cases ; these figures are higher than breast and prostate cancer death rates.
About 1% of the NHS budget is devoted to CHF, with 60% spent on hospital admissions . Between 25% and 30% of heart failure patients are admitted every year and CHF accounts for 5% of all medical admissions to hospital . Quality of life for heart failure sufferers is poor and worse than some other chronic diseases such as diabetes and chronic lung disease . The CHF problem will increase (the so-called heart failure epidemic ) because of the impact of treatment on other forms of CHD (for example thrombolysis) and the ageing population.
Using ACE inhibitors in CHFTreatment of CHF aims to improve:-
If the cause of heart failure is atrial fibrillation, irregular beating of the heart, the first choice medicine remains digoxin, as it has been for hundreds of years. Diuretics are the most effective treatment for heart failure symptoms , but do not improve prognosis. A number of randomised trials have convincingly demonstrated that angiotensin converting enzyme inhibitors (ACEIs) improve symptoms and survival in all grades of heart failure when given with diuretics . A number of ACEIs have been used in trials and the results suggest that the effect is class rather than drug specific. However, enalapril is the best studied drug at present but there are cheaper alternatives (such as ramipril).
The results of two major RCTs involving enalapril demonstrate the beneficial effects. One RCT involved 253 patients with severe congestive heart failure; half were treated with enalapril 2.5 to 40 mg per day. There was a 40% reduction in mortality rate at 6 months and a 31% reduction at 12 months - with all the benefit in patients with progressive heart failure, where the reduction in mortality was 50%.
The second RCT involved 2569 patients with chronic heart failure and reduced left ventricular ejection fractions treated with 2.5 to 20 mg enalapril per day with a follow up averaging 41 months. Enalapril use resulted in a 16% reduction in mortality risk (95% confidence intervals 5-26%); the largest reduction in mortality was seen in patients with progressive heart failure (22% risk reduction, 95% CI 6-35%). There was a significant reduction in the number of hospital admissions with enalapril by about 30%.
A comparison of the effectiveness of some of the commonly used cardiovascular drugs demonstrates the beneficial effects of enalapril, as shown in the Table.
Everyone with CHF who has been stabilised with diuretics should be considered for having an ACEI added to their therapy, unless there are specific contraindications (such as aortic stenosis ). Currently, only about 10% of CHF patients are on ACEI.
In a health authority of 250,000 people, around 40 deaths and 300 hospital admissions could be prevented each year using ACEIs.
Most people (around 98%) could have treatment started in general practice , especially as three ACEIs are licensed for this purpose. Fears about hypotension and renal failure (which meant more people starting treatment in hospital) have been overstated, especially when first doses are low and sensible guidelines followed to detect patients at risk .
Problems with ACEIsThese medicines are generally well tolerated and some of the early problems were because of the high doses used. Cough is a well known problem, but is also common with people with CHF who aren't treated (31% of controls and 37% of enalapril treated patients in trials) and is less of a problem than in patients given ACEIs for hypertension. However, only 1% of people stopped treatment because of their cough. Other adverse effects include rash, taste disturbance and impaired renal function.
Current areas of uncertainty for ACEIsThere are two areas of uncertainty, firstly whether asymptomatic people with left ventricular dysfunction should be treated, and secondly, what is the optimal therapeutic dose.
Studies are in progress to answer these questions.
Direct costs of introducing ACEIsThe impact of introducing ACEIs to patients with CHF in a health authority of 250,000 people over 1 year have been calculated based on published economic analyses [6,12]. The analysis suggests that a net saving could be made by introducing an ACEI to patients if the 98% in whom it was appropriate had treatment started in general practice. The balance between overall savings and costs depends on the proportion of patients whose treatment is initiated by the GP:
Note: SOLVD results  for reduced admission rates, improved survival and usual enalapril dose (20 mg od). Includes capital and revenue costs of an extra echocardiogram machine plus costs of echoes for every patient with CHF. These will be less in subsequent years. Two extra visits to GP per patient per year for monitoring therapy (Fourth National GP Morbidity Survey), extra biochemical tests (to exclude renal impairment) are included. Costs are direct NHS costs for 1990/1 [6,12].
ConclusionLarge improvements in the quality and quantity of life for people with CHF could be achieved by using ACEIs appropriately. Treatment could be introduced at minimal cost to the NHS and might achieve savings. However, costs and savings would be unevenly distributed: primary care would pick up most of the prescribing costs and no apparent savings; the acute sector would pick up capital and revenue costs of echocardiography and any potential savings from reduced hospital admissions. If we are to encourage evidence-based prescribing in this area, these issues need addressing soon.
Questions to be answered
Advice to health authorities and GP fundholders
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