6th May 2025

Investigations

Bedside investigations

• ECG: This may reveal left ventricular hypertrophy, old ischemic changes or arrhythmias
• Urinalysis: May reveal a proteinuria in cardiorenal syndrome

Blood tests

• NT-pro BNP (brain natriuretic peptide): This is a crucial blood test to order as this will determine the urgency of specialist assessment. NT pro-BNP has a sensitivity of 99% and a specificity of 83%, and is an important initial investigation. NT pro-BNP is a metabolite of BNP, which has a sensitivity of 70% and specificity of 99% for heart failure. BNP is secreted from the left ventricular myocardium in response to myocyte stretching, which can occur in volume expansion and increased pressure. This is then cleaved into the bioactive C-terminal of BNP and biologically inactive NT-proBNP, the latter providing a highly sensitive indicator of ventricular dysfunction. 
  • NT pro-BNP >2000: refer the patient for an urgent specialist clinical examination and transthoracic echocardiogram (TTE) within 2 weeks to confirm heart failure 
  • NT pro-BNP 400-2000: refer the patient for a specialist clinical examination and TTE within 6 weeks. 
  • NT pro-BNP <400: consider other causes for the patient’s symptoms
  • NT pro-BNP may be elevated in patients above 70 years old, left ventricular hypertrophy, tachycardia, hypoxia, pulmonary embolism, chronic kidney disease, sepsis, COPD, diabetes mellitus, liver cirrhosis.
  • NT pro-BNP may be reduced in patients with a body mass index (BMI) >35 kg/m2, medications such as diuretics, ACE-inhibitors, ARBs, beta blockers, MRA, African-Caribbean family origin. 
• Full blood count: May reveal anaemia which can worsen heart failure
• Urea and electrolyte: To monitor for renal impairment and crucial in monitoring drug treatment of heart failure such as ACE-inhibitors and diuretics
• Liver function tests: May be raised in hepatic congestion secondary to heart failure 
• Thyroid function test: Thyroid dysfunction may be the cause of a high output heart failure
• Lipids: to monitor risk factors for heart failure

Imaging

• Chest X-ray: in acute decompensated heart failure, a chest x-ray may reveal signs of pulmonary congestion (ABCDE: Alveolar shadowing, kerley B lines, Cardiomegaly, Dilated upper lobe vasculature, Effusion) 
• Transthoracic echocardiogram (TTE): Ultrasound based imaging to assess the left ventricular ejection fraction, cardiac wall thickness, wall motion, valve functions and ventricular cavity size. 
• Cardiac magnetic resonance imaging (CMR): This specialist imaging provides further detail on viability of the myocardium and extent of fibrosis. This can also assess the level of myocardial perfusion. 
• Cardiac CT: To assess coronary vasculature for obstruction