Cardiac Misdiagnosis: A Medico-Legal Guide to Heart Attack and Aortic Dissection Claims

In clinical negligence and personal injury litigation involving cardiac events, the distinction between a tragic outcome and a legally actionable breach often hinges on specialist cardiology expertise. Claims arising from misdiagnosed myocardial infarction or aortic dissection present particular challenges due to the time-critical nature of these conditions, the subtlety of their presentations, and evolving standards of care in acute cardiology. This guide examines the medico-legal landscape from the perspective of a consultant cardiologist expert witness, offering solicitors a framework for instructing specialists in such cases.

Clinical Context: Recognising the Red Flags

In cardiology medico-legal practice, two conditions frequently feature in misdiagnosis claims: acute coronary syndromes (ACS) and acute aortic dissection. Each presents distinct diagnostic challenges, yet both share a common characteristic: the window for effective intervention is narrow, and delays can prove catastrophic.

Acute Coronary Syndromes

ACS encompasses presentations from unstable angina to ST-elevation myocardial infarction (STEMI). The Fourth Universal Definition of Myocardial Infarction classifies ACS into subtypes based on electrocardiographic findings, troponin elevation, and coronary thrombosis presence. In medico-legal assessments, expert opinion addresses whether clinical presentation, ECG findings, and biomarker profile aligned with contemporary diagnostic pathways.

Key considerations include:

• High-sensitivity troponin assays in early rule-out protocols (e.g., 0/1-hour or 0/3-hour pathways)
• ECG interpretation pitfalls (subtle STEMI patterns, posterior MI, de Winter T-waves, Wellens syndrome)
• Risk stratification tools (HEART score, GRACE score, TIMI risk index) guiding chest pain triage
• NICE guidance on assessment and initial management of recent-onset chest pain

Where claimants allege missed diagnosis, expert witnesses evaluate whether clinical assessment, investigations, and referrals adhered to these frameworks. NICE guidance recommends immediate referral for patients with suspected ACS and abnormal ECG to hospitals with percutaneous coronary intervention (PCI) facilities. Failure to do so may constitute breach of duty if causation is established.

Aortic Dissection

Acute aortic dissection is a surgical emergency with mortality increasing approximately 1% per hour in the first 48 hours. The condition is frequently misdiagnosed as ACS due to symptom overlap, including chest pain, syncope, and elevated troponin. However, red flags should prompt consideration of dissection:

• Sudden-onset tearing chest pain radiating to the back
• Pulse or blood pressure asymmetry between limbs
• Neurological deficits (stroke or paraplegia)
• Widened mediastinum on chest X-ray

CT aortogram is the gold standard for diagnosis. Failure to arrange timely imaging may form the basis of negligence claims. Expert witnesses evaluate whether clinical presentation warranted urgent imaging and whether delays fell below standard of care.

Legal Framework: Breach, Causation, and Expert Evidence

In cardiac misdiagnosis claims, legal tests for breach of duty and causation apply within Bolam and Bolitho principles. Expert witnesses assist courts in determining whether care met responsible medical opinion standards and whether breaches caused or contributed to harm.

Breach of Duty

Under Bolam, refined by Bolitho, clinicians are not negligent if actions would be endorsed by responsible medical opinion, provided it withstands logical analysis. In cardiac claims, this involves assessing whether alleged diagnostic or management failures aligned with contemporary guidelines from NICE or the European Society of Cardiology (ESC).

For example, in missed STEMI claims, expert witnesses may opine on whether ECG interpretation met reasonably competent clinician standards. Clear ST-elevation in contiguous leads may be difficult to defend under Bolam, whereas subtle or atypical findings may fall within acceptable practice range.

Causation

Establishing causation in cardiac misdiagnosis claims can be complex, particularly with pre-existing cardiovascular disease or rapidly evolving conditions. Legal principles include:

• Barnett v Chelsea and Kensington HMC (1969): “but for” test requiring proof that harm would not have occurred but for the breach
• Bailey v Ministry of Defence (2008) and Williams v Bermuda Hospitals Board (2016): material contribution test where multiple factors contributed to harm
• Gregg v Scott (2005): requirement to prove breach caused loss of chance of better outcome where harm is probabilistic

In myocardial infarction cases, experts address whether earlier intervention would have preserved myocardial function, reduced complications, or improved survival. For aortic dissection, questions may focus on whether earlier diagnosis and repair would have prevented rupture or malperfusion syndromes.

Common Pitfalls in Cardiac Misdiagnosis Claims

Cardiac misdiagnosis claims frequently involve disputes in these areas:

ECG Interpretation

Subtle findings like ST-depression in leads V1-V3 (posterior MI) or biphasic T-waves (Wellens syndrome) may be overlooked. Experts evaluate whether findings warranted immediate intervention or fell within acceptable variation. Retrospective review may reveal abnormalities not apparent at the time, but this does not necessarily imply negligence if interpretation was reasonable.

Troponin Pathways

High-sensitivity troponin assays enable earlier rule-out of myocardial infarction, but interpretation can be challenging. Mildly elevated troponin in renal impairment or sepsis may not indicate ACS, while normal troponin at presentation does not exclude subsequent infarction. Experts assess whether troponin pathways used were appropriate and whether results were acted upon correctly.

Aortic Dissection Mimics

Aortic dissection is frequently misdiagnosed as ACS, pulmonary embolism, or musculoskeletal pain. Experts consider whether clinical presentation included features raising suspicion of dissection, such as pulse deficits or neurological symptoms. Where dissection was not considered, experts may opine on whether earlier imaging would have altered outcomes.

The Role of the Expert Witness

Expert witnesses in cardiac misdiagnosis claims must possess clinical expertise and thorough understanding of medico-legal processes. Their role extends beyond providing opinions on breach and causation to assisting courts in navigating complexities of cardiac care and expected standards.

CPR Part 35 Compliance

Under CPR Part 35, expert witnesses have an overriding duty to the court. Reports must be independent, unbiased, and based on thorough evidence review. Key requirements include:

• Setting out facts and assumptions underpinning opinions
• Providing reasons for opinions
• Acknowledging evidence limitations or uncertainties
• Addressing alternative explanations for alleged breaches or harm

Experts must ensure reports are accessible to non-specialists, avoiding unnecessary jargon and explaining clinical concepts clearly. Terms like “STEMI” should be defined or contextualised for legal audiences.