Heart failure

Contrubuted by Dr Theresa McDonagh, consultant cardiologist, Royal Brompton, London

Section 1: Definition and epidemiology

Chronic heart failure is a clinical syndrome that causes breathlessness, fatigue and ankle swelling. These symptoms are a result of persistent cardiac dysfunction. 

Most commonly, heart failure is due to ventricular dysfunction, in particular left ventricular systolic dysfunction.

Chronic heart failure is a common condition that affects up to 2 per cent of the population; it becomes increasingly common with age.

Greater survival rates post-MI and an ageing population both contribute to the higher prevalence of heart failure.

Even this figure only represents the tip of an iceberg. The same numbers of patients again have significant left ventricular systolic dysfunction, but no symptoms of heart failure.

Causes and classification
In the UK, the most common underlying cause of heart failure is IHD. Other important contributors to the condition are hypertension, valvular disease of the heart and alcohol abuse.

Less common are high-output states such as anaemia, dilated cardiomyopathies and arrhythmias.

The New York Heart Association classification is widely used. In class one, the patient is asymptomatic with no limitation of activity. Class two is mild, class three, moderate and class four, severe. Class four patients are significantly disabled, breathless at rest and likely to be housebound.

Mortality and morbidity
There is no doubt that chronic heart failure is a major public health problem. Despite all the advances that have revolutionised modern management, the disease still has a substantial mortality.

In its more severe manifestations, up to 50 per cent of patients die within a year of onset.

This is a mortality rate greater than many common cancers, a fact that is easily forgotten. Chronic heart failure is not only lethal, but it is also extremely disabling.

Heart failure patients experience frequent and recurrent episodes of hospitalisation. This use of secondary care facilities means heart failure is an expensive condition that consumes between 1 and 2 per cent of total NHS expenditure.

Long-term cardiac failure reduces quality of life to a much greater extent than other chronic disorders, such as osteoarthritis and rheumatoid arthritis.

Despite this rather gloomy scenario, there is some good news. Over the last 15 years, many new drug treatments and device therapies have made substantial inroads into reducing both the morbidity and mortality associated with the condition.

However, before the maximum use can be made of these latest pharmaceutical advances and treatment technologies, it is essential to establish the underlying condition leading to heart failure.

Section 2: Making a diagnosis

It is crucial not to rely on clinical acumen alone when diagnosing heart failure. A clinical diagnosis of the condition is notoriously inaccurate, whether by a GP or by a specialist.

Only about a quarter of patients presenting with shortness of breath have heart failure.

Patients with an elevated jugular venous pressure or a third heart sound are likely to have heart failure, but these are late signs so the majority of patients will not have them.

The European Society of Cardiology guidelines for diagnosing heart failure state three criteria: symptoms of heart failure at rest or during exercise; objective evidence of cardiac dysfunction at rest; and a response to treatment when the diagnosis is in doubt.

Further investigations are required to establish the diagnosis.

Echocardiography
Cardiac imaging, usually by echocardiography, is necessary to confirm the presence of cardiac dysfunction.

This investigation will also help to ascertain the nature of the disease, by indicating whether it is ventricular, valvular or neither. Unfortunately, rapid access to echocardiography across the UK can be variable.

Because of this, some degree of pre-selection of suspected cases is often required to reduce referrals for echocardiography, and to limit referrals to secondary or tertiary care.

Screening for echocardiography can be done with the aid of three criteria: a previous MI (either on history or an ECG); an abnormal ECG (a completely normal ECG makes heart failure unlikely); and a positive b-type natriuretic peptide (BNP) or N-terminal BNP (N-BNP).

These tests cost about £15 each and are becoming increasingly easily available. The combination of an abnormal ECG and a raised BNP or N-BNP level requires investigation by echocardiography.

BNP testing also provides reassurance for GPs, because if the value is normal in someone they suspect of having heart failure, the diagnosis is highly unlikely and some other cause for the symptoms should be sought.

Referral
Patients with a confirmed diagnosis of heart failure require specialist referral, ideally to a designated heart failure service or to a cardiology clinic.

This will show the underlying aetiology, such as IHD, hypertension or valve disease. Reversible causes and associated factors can then be identified and treated.

Some simple tests including FBC and TFTs are advisable before referral, because anaemia and thyroid dysfunction can both either cause or exacerbate heart failure.

Baseline renal function is also worth testing, as many therapies will affect creatinine concentrations.

Section 3: Treatment of chronic heart failure

Many advances in the treatment of heart failure due to systolic dysfunction have been made over the past two decades.

The cornerstone disease-modifying therapies, that is those shown to reduce both mortality and morbidity, are ACE inhibitors, aldosterone antagonists, beta-blockers and angiotensin receptor antagonists (ARBs).

ACE inhibitors and ARBs
Unless there are specific contraindications, ACE inhibitors should be prescribed to all patients with chronic heart failure due to left ventricular systolic dysfunction.

The dosages aspired to should be those used in the clinical trials of these drugs, namely, enalapril 10-20mg twice daily, captopril 25-50mg three times daily, or ramipril 10mg daily. In general, the highest tolerated dosage should be used.

Angiotensin receptor blockers (ARBs) should be used in patients intolerant of ACE inhibitors due to troublesome cough, for example. The drugs available include candesartan (target dose 32mg daily), losartan 50-100mg daily or valsartan 160mg twice daily. Renal function should be checked a week after starting treatment, as they may cause renal impairment.

Aldosterone antagonists
The aldosterone antagonist spironolactone (25mg daily) has also been shown to reduce mortality in patients with left ventricular dysfunction who remain symptomatic despite ACE inhibitors and a diuretic.

Careful monitoring of electrolytes is required when spironolactone is used, because of the risk of hyperkalaemia.

Another aldosterone antagonist, eplerenone, has been shown to reduce mortality in post-MI heart failure due to left ventricular dysfunction.

Eplerenone does not have the oestrogenic side-effects of spironolactone, but it does require the same careful monitoring of electrolytes.

Beta-blockers
Cardioselective beta-blockers have now been shown to reduce both morbidity and mortality in patients with heart failure across the entire spectrum of severity, and they should be tried in all patients with left ventricular dysfunction. They have to be started at low doses, such as carvedilol 3.125mg twice daily or bisoprolol 1.25mg daily. They are then titrated up over a period of weeks or months to a dose of 25-50mg twice daily for carvedilol, and 10mg daily for bisoprolol.

Section 4: Other treatment strategies

If patients remain symptomatic despite ACE inhibitors and beta-blockers, with or without aldosterone antagonists, it is possible to safely add an ARB such as candesartan to their treatment. This can reduce hospitalisation rates for heart failure. Careful monitoring of the patient's BP and electrolytes is required.

Diuretics and digoxin
Symptomatic treatment for heart failure should include loop diuretics such as furosemide and bumetanide. The minimum dosage required to alleviate symptoms and signs of fluid retention should be used.

Rather than using excessively high dosages of a loop diuretic, thiazide diuretics such as bendroflumethiazide, or the thiazide-like diuretic metolazone can be added for patients with resistant fluid retention.

These days, digoxin is reserved for patients who have heart failure and AF, where it is useful for controlling ventricular rate.

It does not reduce mortality in heart failure, but is helpful in patients who have heart failure and remain symptomatic, are in sinus rhythm, have large hearts and poor ejection fractions.

Dealing with polypharmacy
The complex polypharmacy that is so often needed to treat heart failure is best delivered by a multidisciplinary team working across primary, secondary and tertiary care. It should involve cardiologists with an interest in heart failure, primary care physicians and specialist heart failure nurses. These integrated heart failure networks are gradually being rolled out across the UK.

Devices in heart failure
Heart failure therapy is now moving into the 'device era'. Such technological advances serve to underscore the need for specialist advice in patients needing treatment.

Pacing therapy has been shown to be useful in patients with heart failure due to left ventricular dysfunction.

Automated implantable cardiac defibrillators have been shown to reduce mortality in heart failure patients who have a low ejection fraction after MI, as well as in patients with failure from all causes. Those with milder symptoms tend to benefit more than those with more severe symptoms.

Other devices
Cardiac resynchronisation therapy or biventricular pacing (where the right atrium and the right and left ventricles are paced), either alone or in combination with an implanted defibrillator, can also benefit heart failure patients.

Cardiac resynchronisation therapy in particular seems to confer an improvement in both symptoms and effort capacity, and to reduce the number of episodes of hospitalisation in selected patients with severe failure. This therapy has been recently demonstrated to reduce mortality.

Difficult areas
A substantial proportion of patients with heart failure have preserved systolic function (diastolic dysfunction). Careful investigation of this group of patients is required in order to exclude other causes of their symptoms. These might include obesity, ischaemia and valve disease.

For patients who remain with heart failure and normal left ventricular function, diuretics can help to improve symptoms and signs of fluid retention.

There is evidence that candesartan may reduce hospitalisations in this group of patients.

Progress has been made but there is still much to do. The expansion of multi-professional heart failure programmes in the UK to ensure equity of access to optimum care is essential.

This article was originally published in MIMS Cardiovascular. To register to receive copies go to www.hayreg.co.uk/specials

Resources

Websites for patients

NHS Direct www.nhsdirect.nhs.uk

Netdoctor www.netdoctor.co.uk

Websites for healthcare professionals

British Society for Heart Failure http://www.bsh.org.uk/

NICE www.nice.org.uk

Further reading

NICE. Management of chronic heart failure in adults in primary and secondary care. Clinical Guideline 5. NICE, London, 2003.

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