Heart Attack Misdiagnosis Claims: When a Missed MI Is Negligence

Why heart attacks are misdiagnosed

Myocardial infarction does not always present with crushing central chest pain radiating to the left arm. Atypical presentations — particularly in women, younger patients, and people with diabetes — are a significant source of missed diagnoses. Common atypical presentations include:

• Jaw or back pain without chest pain
• Breathlessness as the primary symptom
• Nausea and abdominal pain mistaken for gastrointestinal illness
• Fatigue without chest pain in women
• Heartburn-type symptoms

Clinicians assessing chest pain are expected to consider and exclude cardiac causes before attributing symptoms to non-cardiac causes. Cardiac risk factors (hypertension, diabetes, hypercholesterolaemia, smoking, family history) must be taken into account.

The clinical standards for chest pain assessment

NICE guidance (NG185) and cardiology standards require:

• A 12-lead ECG performed within 10 minutes of first clinical assessment for patients with chest pain
• Troponin levels measured at presentation and again at 3 hours (high-sensitivity troponin assays) to rule in or rule out acute MI
• STEMI patients sent immediately to a cardiac catheterisation laboratory for PPCI
• NSTEMI patients risk-stratified and treated with anticoagulation and early intervention

Failure to perform an ECG, to measure troponin, to correctly interpret ECG findings, or to refer a STEMI patient urgently for PPCI are all potential bases for a claim where they cause harm.

Common scenarios in heart attack misdiagnosis claims

Atypical MI sent home from A&E

A patient (often a woman or a patient with diabetes) presents with breathlessness, nausea, or jaw pain. A chest infection or gastrointestinal cause is assumed. An ECG is not performed or is misread. Troponin is not checked. The patient is sent home and suffers a major MI or cardiac arrest.

ECG misreported by GP or A&E clinician

An ECG showing ST-elevation or new left bundle branch block — both indicating STEMI — is not recognised by the reading clinician. The patient is not transferred urgently to a cardiac centre.

NSTEMI discharged without treatment

A patient with an NSTEMI — shown by elevated troponin — is discharged without anticoagulation or early angiography referral. They suffer further myocardial damage or a subsequent MI that appropriate treatment would have prevented.

Out-of-hours telephone triage failure

A patient calls 111 or an out-of-hours service with chest pain. The triage system does not identify the call as a potential cardiac emergency. The patient is advised to see a GP the next day and deteriorates overnight.

What do you need to prove?

1. Duty of care — the clinician owed a duty to assess and treat you competently.
2. Breach of duty — the failure to diagnose or treat the MI fell below the standard of a reasonably competent clinician. An independent cardiology expert will assess this.
3. Causation — the delay caused additional myocardial damage or death beyond what timely treatment would have caused.
4. Damage — reduced cardiac function, heart failure, permanent disability, or death.

Compensation

Compensation depends on the degree of additional cardiac damage caused by the missed diagnosis. A delay causing a modest reduction in left ventricular function may result in a moderate award. Where the missed MI causes severe heart failure, inability to work, or death, compensation including future care and dependency can be substantial.

Frequently asked questions

Related guides

• Medical negligence claims — complete guide
• A&E negligence claims
• Misdiagnosis claims
• Compensation after a death from medical negligence