High-sensitivity troponin and the breach of duty in chest pain claims

The Clinical Framework of High-Sensitivity Troponin Pathways

In clinical negligence litigation, the interpretation of cardiac biomarkers and adherence to diagnostic pathways frequently form the basis of allegations concerning a breach of duty. The adoption of high-sensitivity troponin (hs-troponin) assays has refined the diagnosis of myocardial infarction, but it introduces complexities regarding sampling intervals, delta-change calculations, and the interpretation of results in the context of the Fourth Universal Definition of MI. In the acute assessment of chest pain, clinicians often utilize structured pathways, such as those discussed in NICE guidance NG185, which support risk stratification via serial troponin sampling.

For legal practitioners, the central medico-legal issue is whether the clinician followed a defensible protocol and whether the decision-making process satisfies the Bolam and Bolitho tests. An expert must consider whether the clinician interpreted hs-troponin results in accordance with local policy and established cardiovascular standards. Disputes often arise regarding ‘borderline’ elevations—which may indicate non-ischemic myocardial injury rather than acute infarction. Where a clinical diagnosis of NSTEMI or unstable angina is challenged, the cardiologists providing expert evidence must scrutinise the totality of the clinical evidence, including serial ECG changes and the application of validated risk-stratification tools.

Legal Relevance: Breach, Causation, and the Bolam/Bolitho Test

Under CPR Part 35, the expert witness provides an independent opinion to the court on whether the standard of care fell below that of a responsible body of medical opinion. In cardiac claims, the expert addresses the ‘but-for’ test: if the patient had been admitted for further investigation or serial monitoring, would the infarction have been diagnosed in a timeframe that would have altered the clinical outcome? It is vital to distinguish between a failure to diagnose, which may constitute a breach, and an adverse cardiac outcome that occurred despite reasonable care. The court evaluates whether the clinician acted in a way that was logically defensible, considering the patient’s symptoms, risk factors, and available diagnostic data.

Common Pitfalls in Medico-Legal Cardiac Claims

Disputes in chest pain claims often centre on the following areas:

• ECG Interpretation: Allegations that subtle signs of myocardial ischaemia—such as Wellens’ syndrome or de Winter patterns—were overlooked despite the presence of non-diagnostic or borderline hs-troponin levels.
• Sampling Discontinuity: Instances where the protocol for repeat testing was interrupted or delayed, potentially missing the diagnostic ‘delta’ in troponin levels.
• Risk Stratification Bias: Over-reliance on a single troponin level at presentation in patients with atypical symptoms or high-risk demographics, potentially disregarding the need for formal risk scoring.
• Documentation Deficits: A lack of clear rationale for discharging a patient with persistent chest pain, including the adequacy of safety-netting and advice to return if symptoms recur.

The Role of the Expert Witness and Procedural Compliance

The expert’s role is governed by the duty to the court under CPR 35.3. Where proceedings are ongoing, the court may direct experts to participate in discussions under CPR 35.12 to narrow issues. This process of producing a joint statement is distinct from the appointment of a single joint expert (SJE) under CPR 35.7. If an SJE is appointed, the experts receive their instructions under CPR 35.8. An SJE does not undertake a joint statement process with a second expert, as they are the sole source of expert evidence on that issue.

When instructing a cardiologist, solicitors should ensure the expert has access to the full clinical record, including raw troponin data and contemporaneous ECGs. A robust, CPR Part 35 compliant report should clearly distinguish between clinical facts, the expert’s clinical judgement, and the reasoning behind the opinion on breach of duty and causation. In complex claims, seeking subspecialty input—such as an interventional cardiologist for matters relating to PCI or an electrophysiologist for arrhythmia-related mortality—can be essential to ensuring the evidence presented is authoritative and precise.