What initial investigations are recommended for a patient with suspect

Guideline-aligned answer with reasoning, red flags and references. Clinically reviewed by Dr Kola Tytler MBBS CertHE MBA MRCGP.

In a primary care setting, for a patient with suspected non-ST elevation myocardial infarction (NSTEMI), the initial investigations recommended are:

Perform a resting 12-lead ECG as soon as possible to detect ischaemic changes or exclude ST elevation myocardial infarction (STEMI), which requires urgent hospital referral.
Monitor oxygen saturation using pulse oximetry to assess the need for supplemental oxygen, but do not routinely administer oxygen unless saturation is below 94% (or 88-92% in patients at risk of hypercapnic respiratory failure).
Assess vital signs and clinical status including pulse, blood pressure, heart rhythm, and symptom progression.
Offer a single loading dose of 300 mg aspirin unless contraindicated, and arrange urgent hospital transfer for further assessment and management including high-sensitivity troponin testing.
Consider a chest X-ray if there is suspicion of complications such as pulmonary oedema or alternative diagnoses like pneumothorax or pneumonia.

Blood tests for high-sensitivity troponin and further diagnostic workup should be performed in hospital rather than primary care.

Non-invasive imaging or exercise ECG are not routinely recommended in the initial assessment of acute cardiac chest pain in primary care.

Immediate specialist referral is essential for definitive diagnosis and management.

What initial investigations are recommended for a patient with suspected NSTEMI in a primary care setting?