Heart Failure: Symptoms, Causes, Diagnosis & NHS Treatment

Heart failure is a serious chronic condition in which the heart is unable to pump blood effectively enough to meet the body’s needs. It affects around 900,000 people in the UK and accounts for over 1 million hospital bed days per year. Despite its name, heart failure does not mean the heart has stopped — it means the heart is working less efficiently. With appropriate treatment and self-management, many people live well with heart failure for years.

What Is Heart Failure?

Heart failure occurs when the heart cannot maintain adequate cardiac output to meet the body’s metabolic demands. It is a clinical syndrome defined by symptoms (breathlessness, ankle swelling, fatigue) and signs (elevated jugular venous pressure, bilateral leg oedema, pulmonary crackles) caused by a structural or functional abnormality of the heart. Heart failure is not a single diagnosis but a final common pathway for many cardiac conditions.

Heart failure is classified by the left ventricular ejection fraction (LVEF) — the percentage of blood pumped out of the left ventricle with each beat. Heart failure with reduced ejection fraction (HFrEF) is defined as LVEF below 40%; heart failure with mildly reduced ejection fraction (HFmrEF) as LVEF 40–49%; and heart failure with preserved ejection fraction (HFpEF) as LVEF 50% or above with evidence of cardiac structural or functional abnormality. This classification is clinically important as drug treatments differ significantly between these groups.

Causes of Heart Failure

The most common cause of heart failure in the UK is coronary artery disease — particularly previous myocardial infarction (heart attack), which can damage and weaken the heart muscle. Other important causes include: hypertension (long-standing high blood pressure causing left ventricular hypertrophy and diastolic dysfunction); cardiomyopathy (dilated, hypertrophic, or restrictive cardiomyopathy — the latter includes conditions such as cardiac amyloidosis, which is increasingly recognised as an underdiagnosed cause of HFpEF in older adults); valve disease (mitral regurgitation, aortic stenosis); arrhythmias (particularly atrial fibrillation, which both causes and is exacerbated by heart failure); alcohol (alcoholic cardiomyopathy); chemotherapy-related cardiotoxicity (particularly anthracyclines and trastuzumab); viral myocarditis; and congenital heart disease.

Symptoms of Heart Failure

The cardinal symptoms of heart failure are breathlessness (dyspnoea) — initially on exertion but later at rest; orthopnoea (breathlessness lying flat, requiring multiple pillows); paroxysmal nocturnal dyspnoea (sudden breathlessness waking from sleep); ankle and leg swelling (peripheral oedema); fatigue and exercise intolerance; and in severe cases, abdominal distension (ascites) and rapid unintentional weight gain from fluid retention.

Symptoms of low cardiac output include fatigue, reduced exercise tolerance, poor concentration, and in advanced heart failure, cardiac cachexia (severe unintentional weight loss from reduced appetite and increased catabolism). The New York Heart Association (NYHA) classification grades functional limitation from Class I (no symptoms with ordinary activity) through to Class IV (symptoms at rest).

Diagnosing Heart Failure

NICE guideline NG106 recommends a structured diagnostic pathway. The first step is measurement of serum N-terminal pro-B-type natriuretic peptide (NT-proBNP) or BNP. These natriuretic peptides are released by the heart when under stress and are powerful diagnostic biomarkers. A raised NT-proBNP (above 400 pg/mL for suspected new heart failure) triggers urgent referral for specialist assessment and echocardiography within 2 weeks. A very high NT-proBNP (above 2000 pg/mL) requires even more urgent assessment within 2 weeks regardless of other findings.

Echocardiography (echo) is the key diagnostic investigation — it determines the LVEF, assesses chamber size and wall motion, evaluates valve function, and estimates filling pressures. It is essential to classify heart failure (HFrEF vs HFpEF) and guide treatment. Additional investigations include: 12-lead ECG (may show previous MI, left bundle branch block, atrial fibrillation, or left ventricular hypertrophy); chest X-ray (cardiomegaly, pulmonary oedema, pleural effusions); full blood count and renal function (anaemia and renal impairment are common comorbidities); thyroid function (hyperthyroidism can precipitate heart failure); and iron studies (iron deficiency is very common in heart failure and is an independent predictor of poor outcomes).

NHS Treatment: HFrEF (NICE NG106)

Heart failure with reduced ejection fraction (HFrEF, LVEF below 40%) has a well-established evidence-based treatment framework. The goal of treatment is to improve symptoms, reduce hospitalisations, and reduce mortality.

Four pillars of HFrEF pharmacotherapy:

1. ACE inhibitor or ARB or ARNI: ACE inhibitors (e.g., ramipril, lisinopril) are first-line agents, reducing afterload and neurohormonal activation. If ACE inhibitors are not tolerated due to cough, an angiotensin receptor blocker (ARB) such as candesartan is used. In patients already established on ACE inhibitor or ARB who remain symptomatic, the ARNI sacubitril/valsartan (Entresto) should replace the ACE inhibitor or ARB — it has been shown to reduce mortality more effectively than enalapril in the PARADIGM-HF trial and is recommended by NICE.

2. Beta-blocker: Carvedilol, bisoprolol, or nebivolol are the only beta-blockers licensed and proven to reduce mortality in HFrEF. They should be started at low doses and titrated up gradually. Beta-blockers reduce heart rate, oxygen demand, and the risk of sudden cardiac death from ventricular arrhythmia.

3. Mineralocorticoid receptor antagonist (MRA): Spironolactone or eplerenone are recommended for patients with persistent symptoms (NYHA Class II–IV) on ACE inhibitor and beta-blocker. They reduce fluid retention and have been shown to reduce mortality in HFrEF. Potassium levels and renal function must be monitored carefully due to the risk of hyperkalaemia.

4. SGLT2 inhibitor: Dapagliflozin and empagliflozin are now recommended by NICE for HFrEF. These drugs, originally developed for type 2 diabetes, have been shown in landmark trials (DAPA-HF, EMPEROR-Reduced) to reduce hospitalisation for heart failure and cardiovascular death, and this benefit is seen regardless of diabetes status. They are now considered a cornerstone of heart failure treatment.

Additional treatments include diuretics (loop diuretics such as furosemide) for symptomatic relief of fluid overload — they do not improve survival but are essential for symptom control. Ivabradine (reduces heart rate in patients in sinus rhythm with heart rate above 75 bpm) and hydralazine plus nitrate (for patients unable to tolerate ACE inhibitors/ARBs/ARNIs — particularly relevant in patients of African or Caribbean descent) are options in selected patients.

Device Therapy

Implantable cardioverter-defibrillator (ICD) therapy is recommended for patients with HFrEF (LVEF below 35%) who remain at risk of sudden cardiac death despite optimal medical therapy. Cardiac resynchronisation therapy (CRT) — a pacemaker with leads to both ventricles — is recommended for patients with HFrEF and left bundle branch block (QRS duration ≥150 ms), improving cardiac synchrony, symptoms, and prognosis. Combined CRT-defibrillator (CRT-D) devices are used when both are indicated. Implantable haemodynamic monitors may be considered in selected patients to guide outpatient management.

Advanced Heart Failure

In advanced heart failure (NYHA Class IV, refractory to optimal medical and device therapy), specialist options include inotropic support (dobutamine, milrinone — typically for hospitalised patients), left ventricular assist devices (LVADs) as destination therapy or bridge to transplantation, and heart transplantation for carefully selected patients. Palliative care integration is essential in advanced heart failure to manage symptoms, quality of life, and end-of-life planning.

Monitoring and Self-Management

Patients with heart failure should weigh themselves daily. A weight gain of more than 2 kg over 2 days indicates fluid retention and should prompt contact with their heart failure team or use of a flexible diuretic plan if agreed. Fluid restriction (typically 1.5–2 litres daily) is recommended in patients with severe or recurrent fluid overload. Salt restriction (below 6 g daily) and alcohol moderation are important lifestyle measures. Regular moderate aerobic exercise is beneficial — cardiac rehabilitation programmes specifically designed for heart failure are available. Annual flu and pneumococcal vaccinations are recommended.

Heart failure specialist nurses are central to NHS heart failure care — they provide patient education, monitor symptoms, optimise medications, and reduce hospitalisation rates. All patients should have a personalised heart failure care plan and regular structured review.