Which investigations should be prioritized in a patient suspected of having restrictive cardiomyopathy?

Prioritized investigations for suspected restrictive cardiomyopathy include:

• Transthoracic echocardiography to assess cardiac structure and function, particularly diastolic function and ventricular wall thickness, which are key in restrictive cardiomyopathy diagnosis.
• Measurement of N-terminal pro-B-type natriuretic peptide (NT-proBNP) to support the diagnosis of heart failure and assess severity, as elevated levels are common in restrictive cardiomyopathy.
• Cardiac magnetic resonance imaging (MRI) if echocardiography is inconclusive, to provide detailed myocardial tissue characterization and detect fibrosis or infiltration.
• Electrocardiogram (ECG) to identify conduction abnormalities or arrhythmias that may accompany restrictive cardiomyopathy.
• Blood tests including full blood count, renal and liver function, and specific tests to exclude infiltrative causes such as amyloidosis (e.g., serum free light chains).
• Endomyocardial biopsy may be considered in selected cases to confirm diagnosis and identify specific aetiologies.

These investigations align with the approach to diagnosing heart failure and cardiomyopathies, emphasizing echocardiography and natriuretic peptide measurement as initial steps, followed by advanced imaging and tissue diagnosis as needed NICE NG106.