The Basics - Heart failure

No one symptom or sign can be considered specific for a diagnosis of heart failure, says Dr Keith Barnard.

The overall prevalence of heart failure is between three and 20 per 1,000 population, but it is age related and rises to 100 per 1,000 in those aged 65 years or more.1

Prevalence is higher in men. As the population ages and treatment advances enable more people to survive acute MIs, cases of heart failure are likely to rise.

Enlargement of the left ventricle: cardiomyopathy is a cause of low output heart failure (Photograph:SIMON FRASER/SCIENCE PHOTO LIBRARY)

There is no one symptom or sign that can be considered specific for a diagnosis of heart failure. The main clinical pointers to the condition are breathlessness, intolerance of exertion and fluid retention.

Heart failure can be caused by systolic or diastolic dysfunction. Coronary artery disease is the underlying cause in most cases of heart failure, and other risk factors include diabetes mellitus, hyperlipidaemia and smoking.

Heart failure may be classified as low output or high output.

Low-output failure
Low-output failure is where output is unable to adequately perfuse body organs. This includes:

  • Pump failure. This may be due to infarction, cardiomyopathy, myocarditis or infiltrative diseases; aortic stenosis and hypertension; constrictive pericarditis; dysrhythmias, such as persistent tachycardia, AF, and heart block; and negatively inotropic drugs including alcohol and many antiarrhythmic agents;
  • Excessive preload, associated with aortic or mitral regurgitation; ventricular and atrial septal defects; pulmonary hypertension and pulmonary embolus;
  • Secondary to right heart failure as in pulmonary hypertension, pulmonary embolism or tricuspid valve incompetence;
  • Fluid overload. This may be associated with impaired renal excretion or excess IV infusion.

High-output failure
In high-output failure, cardiac output is normal or increased due to increased demand. This will occur even in the normal heart when it fails to meet the body's requirement. Causes include heart disease associated with pregnancy or severe anaemia, hyperthyroidism and arteriovenous malformations.

Investigation and diagnosis
Heart failure can be a difficult clinical diagnosis because many features are not organ specific and in the early stages there may be few clinical signs. All patients with suspected cardiac failure should have a range of basic tests, including an FBC, U+Es, fasting blood glucose, TFTs, urinalysis and a chest X-ray.

A 12-lead ECG should be performed, and in recent years diagnosis has been aided by the introduction of brain natriuretic peptide (BNP) testing.

Where this is available, it can be useful in excluding left ventricular failure (LVF) as a cause of breathlessness. If the BNP level is low, heart failure as a cause of dyspnoea is unlikely.

Echocardiography is an essential investigation and should be performed in any patient with suspected heart failure. It is increasingly available at open access clinics.

An assessment can be made of left ventricular function and ejection fraction, wall thickness and movement abnormalities, diastolic function and valve disease.

Heart failure is usually associated with a left ventricular ejection fraction below 0.4, but in a few cases it may occur with a normal ejection fraction, usually in cases of hypertensive left ventricular hypertrophy, AF and IHD.

The severity of heart failure is often assessed using the New York Heart Association's criteria (see box, above). The prognosis of heart failure, even with optimal treatment, has a five-year survival of 25 to 75 per cent, often because of sudden death following ventricular arrhythmia.

Management
A multidisciplinary team approach is essential, and patients need to be able to discuss the implications of the diagnosis for their future.

Patients diagnosed with heart failure need to modify their behaviour.

Measures include avoiding excess alcohol consumption, stopping smoking and, once stabilised, undertaking regular low-intensity physical activity.

Dietary changes should encourage the reduction of salt intake below 6g/day (but avoiding salt substitutes that have a high potassium content), a balanced fluid intake, and weight loss if they are obese.

Regular weighing at the same time each day can be useful in predicting destabilisation, and a sudden weight gain of 1.5kg or more over 48 hours should be reported immediately.

Established patients should be advised to avoid grapefruit juice if they are taking simvastatin and cranberry juice if they are on warfarin. St John's wort may interact with digoxin and warfarin.

Pharmacotherapy
ACE inhibitors should be considered in all cases of heart failure due to LVF. Beta-blockers should be used in all patients once they are stabilised, provided there are no contraindications.

Angiotensin receptor blockers (ARBs) should be considered in patients with left ventricular dysfunction, or heart failure after MI, who cannot tolerate ACE inhibitors.

An ARB may be added to patients who are symptomatic despite optimal use of ACE inhibitors and beta-blockers.

Patients with severe LVF may require an aldosterone antagonist. This is generally introduced with specialist advice in patients with adequate renal function and normal potassium levels.

Diuretics can help patients with persistent breathlessness or peripheral oedema.

Digoxin now has a limited role, and is only used in patients in sinus rhythm who are still symptomatic after optimum therapy.

  • Dr Barnard is a former GP in Hampshire and until recently editor of European Perspectives in Cardiology.

Classifying severity

New York Heart Association severity classification (abbreviated)

Class I: No symptoms on normal physical activity.

Class II: Slight limitation of physical activity by symptoms.

Class III: Even reduced activity causes symptoms.

Class IV: Unable to carry out any activity without symptoms.


References

1. Davis R C, Hobbs F D, Lip G Y. ABC of heart failure. History and epidemiology. BMJ 2000; 320: 39-42.

Learning Points

  • GPs should press for nationwide BNP testing availability and open access echocardiography.
  • Involve a multidisciplinary team to advise on diet, moderate exercise, and improve drug knowledge and compliance.
  • Palliative care, when required, should be aimed at symptom relief and stopping non-essential treatments.
  • The early recognition of heart failure is increasingly important to maximise recent advances in drug treatment and advanced surgical procedures.

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