Identification of the condition responsible for the cardiac structural and/or functional abnormalities may be important, because some conditions that lead to left ventricular dysfunction are potentially treatable and/or reversible. Efforts to identify a cause frequently allow the detection of co-existent conditions that may contribute to or exacerbate the severity of symptoms. However, it may not be possible to discern the cause of heart failure in many patients presenting with this syndrome, and in others, the underlying condition may not be amenable to treatment.
Heart failure is primarily a condition of older people. The incidence and prevalence of heart failure increases with increasing age. In 2014 there were 1 million new cases in patients aged >55 years. Among patients aged >80 years, the prevalence of heart failure is 14.1% in males and 13.4% in females. Increasing age has been consistently linked to a higher risk. Male sex has also been linked to a higher risk of developing heart failure. Excess body weight is an established risk factor.
A number of precipitating factors may lead to impaired cardiac function, potentially leading to an episode of acute heart failure. Detection and treatment of precipitating factors plays an important role in patient management. Precipitating factors include excessive salt intake, lack of adherence (with respect to medication and diet), myocardial infarction, pulmonary embolism, uncontrolled hypertension, cardiac arrhythmias, infection, hypothyroidism, hyperthyroidism, renal dysfunction, and alcohol and drug abuse.
The complexity and variety of potential causative factors means that a multitude of patient historical factors may be relevant. A history of hypertension; diabetes mellitus; dyslipidaemia; tobacco use; coronary, valvular, or peripheral vascular disease; rheumatic fever; heart murmur or congenital heart disease; personal or family history of myopathy; mediastinal irradiation; and sleep-disturbed breathing should be enquired about. The drug history should record the past or current use of illicit drugs; alcohol; ephedra; or antineoplastic agents such as anthracyclines, trastuzumab, or high-dose cyclophosphamide, because heart failure may occur years after exposure to doxorubicin or cyclophosphamide. The history and physical evaluation should include specific consideration of non-cardiac diseases such as collagen vascular disease, bacterial or parasitic infection, obesity, thyroid excess or deficiency, amyloidosis, and phaeochromocytoma.
A detailed family history should be obtained, not only to determine whether there is a familial pre-disposition to atherosclerotic disease but also to identify relatives with cardiomyopathy, sudden unexplained death, conduction system disease, and skeletal myopathies.
Dyspnoea on exertion or at rest is the most common symptom of left-sided heart failure. With increasing failure patient may develop leg oedema and abdominal distension due to ascites.
Particular attention should be paid to the cardinal signs and symptoms of heart failure. Their presence (and degree) may depend on severity of heart failure and associated comorbid disease.
General examination may reveal tachycardia and cyanosis. A focused cardiovascular examination may reveal elevated jugular venous pressure, ankle oedema, and a displaced apex beat, which suggests cardiomegaly. On auscultation, besides presence of pulmonary rales or crepitation, an S3 gallop may be present, which has prognostic significance.
Particular attention should be paid to factors like pallor (which may reflect anaemia), irregularly irregular pulse (reflecting atrial fibrillation), systolic murmur of aortic stenosis and mid diastolic murmur of mitral stenosis, or overt signs of thyrotoxicosis. In dialysis patients, a large arteriovenous fistula may occasionally be the precipitating factor.
For all patients, initial investigations should include ECG, chest x-ray, transthoracic echocardiogram, and baseline haematology and blood chemistry, including full blood count, serum electrolytes (including calcium and magnesium), serum urea and creatinine, liver function tests, and B-type natriuretic peptide/N-terminal pro-brain natriuretic peptide levels. Anaemia and high lymphocyte percentage are strong risk factors and prognostic markers of poor survival. In patients presenting with dyspnoea, measurement of natriuretic peptide biomarkers is useful to support a diagnosis or exclude heart failure. However, elevated plasma levels of natriuretic peptides can occur with a wide variety of cardiac and non-cardiac causes; therefore, clinical judgement is necessary.
Blood glucose, thyroid function tests and blood lipids are useful to assess for commonly associated comorbid disease.
Subsequent investigations that help in assessing severity of heart failure and functional status include standard exercise stress testing (bicycle or treadmill), cardiopulmonary exercise testing with VO₂ max, 6-minute walking test exercise, right heart catheterisation, and endomyocardial biopsy. Based on clinical history, HIV screening and measurement of iron levels and fasting transferrin saturation to screen for haemochromatosis may also be performed. A cardiac magnetic resonance imaging scan is particularly useful in the investigation of myocarditis and infiltrative cardiomyopathy.
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