How to Instruct a Single Joint Expert (SJE) in Delayed Myocardial Infarction Claims Under CPR Part 35

Delayed diagnosis of myocardial infarction (MI) remains a recurrent theme in coronary clinical negligence claims. The complexities of high-sensitivity troponin pathways, subtle ECG presentations, and the interplay between pre-existing cardiac disease and acute ischaemic events frequently necessitate specialist cardiology input. Instructing a Single Joint Expert (SJE) under CPR Part 35 can streamline proceedings, but the process demands precision—particularly in cases where causation, apportionment, or life expectancy are contested. This guide addresses the key considerations for solicitors handling such claims.

1. Clinical Context: Delayed Myocardial Infarction and the Medico-Legal Framework

1.1 The Fourth Universal Definition of MI and Diagnostic Pathways

In cardiology medico-legal practice, the Fourth Universal Definition of Myocardial Infarction (2018) provides the cornerstone for classifying acute coronary events. Delayed MI claims typically centre on Type 1 MI (spontaneous plaque rupture) or, less commonly, Type 2 MI (ischaemia due to supply-demand mismatch). The distinction is critical: Type 1 MI carries a higher risk of recurrent events and mortality, while Type 2 MI may reflect underlying comorbidities rather than acute coronary occlusion.

Diagnostic pathways in the UK follow NICE guidance (NG185, 2020) and ESC frameworks, which mandate:

• High-sensitivity troponin (hs-cTn) testing at 0 and 1 hour (or 0 and 3 hours in some centres), with delta changes interpreted against rule-out/rule-in thresholds.
• ECG interpretation for subtle STEMI equivalents (e.g., de Winter T-waves, Wellens syndrome, posterior MI) or non-diagnostic changes (e.g., T-wave inversion without ST elevation).
• Risk stratification using tools such as HEART, GRACE, or TIMI scores to guide triage and management.

In delayed MI claims, expert opinion may address whether the alleged index events fell below the standard of care expected of a reasonably competent clinician, applying the Bolam/Bolitho test. For example, failure to recognise a dynamic troponin rise or misinterpreting an ECG with subtle ischaemic changes could constitute a breach of duty if no responsible body of clinicians would have acted similarly.

1.2 Common Pitfalls in Delayed MI Diagnosis

Several recurring issues arise in medico-legal assessments of delayed MI:

• Troponin misinterpretation: A single elevated hs-cTn result may reflect chronic kidney disease, heart failure, or demand ischaemia rather than acute MI. Serial testing and delta analysis are essential.
• ECG pitfalls: Posterior MI (V7–V9 leads), left bundle branch block, or paced rhythms can obscure ischaemic changes. Expert review of serial ECGs is often required.
• Risk stratification errors: Low-risk patients (e.g., HEART score <3) may be inappropriately discharged without further investigation, while high-risk patients (e.g., GRACE score >140) may not receive timely angiography.
• Apportionment against pre-existing disease: Where the claimant had prior coronary artery disease, experts must assess whether the alleged delay materially contributed to the outcome (applying Bailey v MoD or Williams v Bermuda Hospitals Board).

2. Legal Relevance: CPR Part 35 and the Role of the SJE

2.1 When to Consider an SJE in Delayed MI Claims

CPR Part 35 governs the instruction of experts in civil proceedings, including clinical negligence claims. An SJE may be appropriate where:

• The parties agree that a single expert can provide an impartial opinion on breach, causation, or condition/prognosis.
• The issues are sufficiently narrow (e.g., interpretation of troponin trends or ECG changes) to avoid conflicts of interest.
• The court directs an SJE under CPR 35.7, particularly in cases where proportionality or cost management is a concern.

In delayed MI claims, an SJE is often instructed for:

• Breach of duty reports: Assessing whether the alleged index events fell below the standard of care (Bolam/Bolitho).
• Causation reports: Determining whether the delay materially contributed to the claimant’s outcome (applying material contribution principles).
• Condition & prognosis reports: Evaluating the claimant’s current cardiac status, future risk of events, and life expectancy (using heart failure survival models or ESC risk calculators).
• Joint statements: Clarifying areas of agreement/disagreement with opposing experts following a Part 35 experts’ meeting.

2.2 Key Authorities and Legal Tests

Several legal principles are particularly relevant to delayed MI claims:

• Bolam v Friern Hospital Management Committee [1957] 1 WLR 582: The standard of care is that of a reasonably competent clinician in the relevant field.
• Bolitho v City and Hackney Health Authority [1998] AC 232: The court may reject a body of expert opinion if it is not logically defensible.
• Montgomery v Lanarkshire Health Board [2015] UKSC 11: Clinicians must disclose material risks to patients; failure to do so may constitute negligence.
• Gregg v Scott [2005] UKHL 2: Loss of chance arguments in delayed diagnosis claims are challenging but not impossible to establish.
• Khan v Meadows [2021] UKSC 21: The scope of duty must be carefully defined, particularly where pre-existing conditions are present.

3. Practical Guidance: Instructing a Cardiology SJE

3.1 Selecting the Right Expert

Not all cardiologists are equally equipped to serve as medico-legal experts. When instructing an SJE in delayed MI claims, consider:

• Subspecialty expertise: An interventional cardiologist may be better placed to opine on PCI-related delays, while a heart failure specialist may be more suited to prognosis assessments.
• Medico-legal experience: The expert should be familiar with CPR Part 35, joint statements, and the legal tests for breach and causation.
• Impartiality: The SJE must be able to provide an independent opinion, free from bias toward either party.

3.2 Drafting Instructions: What to Include

Clear, focused instructions are essential to obtaining a useful SJE report. Key elements to address include:

• Background: A concise summary of the alleged index events, including dates, presenting symptoms, and initial management.
• Clinical records: Specify which records and imaging should be reviewed (e.g., ambulance records, ED notes, troponin results, ECGs, angiogram reports, discharge summaries).
• Questions for the expert:
  • Did the alleged index events fall below the standard of care expected of a reasonably competent clinician?
  • If so, did the breach materially contribute to the claimant’s outcome (applying material contribution principles)?
  • What is the claimant’s current cardiac status, and what is their prognosis (e.g., risk of future MI, heart failure, or sudden cardiac death)?
  • If the claimant had pre-existing coronary disease, what proportion of their outcome is attributable to the alleged delay?
• Guidelines and frameworks: Direct the expert to relevant NICE, ESC, or ACC/AHA guidance (e.g., NICE NG185 for chest pain, ESC 2020 guidelines for non-ST-elevation ACS).
• Assumptions: Clarify any factual assumptions (e.g., “Assume the claimant presented with central chest pain radiating to the left arm and diaphoresis”).

3.3 Managing the SJE Process

Once the SJE is instructed, solicitors should:

• Provide all relevant records promptly: Delays in disclosure can hinder the expert’s ability to form a timely opinion. Ensure ECGs are provided in full (including posterior leads if available) and that troponin results are clearly tabulated.
• Facilitate access to imaging: If angiography, echocardiography, or cardiac MRI is relevant, ensure the expert can review the original images (not just reports).
• Clarify any ambiguities: If the expert raises questions about the clinical timeline or missing records, address these promptly to avoid delays.
• Prepare for the joint statement: If the SJE is to meet with other experts, ensure they are briefed on the key areas of dispute (e.g., troponin interpretation, ECG changes, or apportionment).

4. Common Disputes and How to Address Them

4.1 Troponin Interpretation

Disputes often arise over whether a single elevated troponin result indicates acute MI. The SJE should be asked to review serial troponin results, assess whether the pattern is consistent with acute MI, and opine on whether the alleged delay in testing fell below the standard of care.

4.2 ECG Changes and Subtle STEMI

Subtle ECG changes (e.g., de Winter T-waves, Wellens syndrome, or posterior MI) are frequently missed in clinical practice. The SJE should:

• Review all available ECGs, including posterior leads (V7–V9) if performed.
• Assess whether the changes were diagnostic of acute ischaemia at the time of presentation.
• Opine on whether a reasonably competent clinician would have recognised the changes and acted accordingly.

4.3 Apportionment Against Pre-Existing Disease

Where the claimant had prior coronary artery disease, the SJE must address whether the alleged delay materially contributed to the outcome. This requires:

• Review of the claimant’s pre-existing cardiac history (e.g., prior MI, PCI, or CABG).
• Assessment of whether the alleged delay altered the natural history of the disease.
• Application of material contribution principles, as established in Bailey v MoD and Williams v Bermuda Hospitals Board.

4.4 Life Expectancy and Prognosis

In fatal delayed MI claims, the SJE may be asked to opine on the claimant’s life expectancy had the alleged delay not occurred. This requires:

• Review of the claimant’s cardiac function (e.g., ejection fraction, NYHA class, or CCS angina grading).
• Assessment of their risk of future events (e.g., using ESC risk calculators or heart failure survival models).
• Consideration of whether the alleged delay shortened their life expectancy (applying Gregg v Scott principles).

5. Practical Takeaways for Legal Practitioners

Instructing a cardiology SJE in delayed MI claims requires careful planning and specialist input. Key considerations include:

• Early instruction: Engage a cardiology expert early to assess breach and causation, particularly where troponin trends or ECG changes are disputed.
• Subspecialty expertise: Ensure the expert’s subspecialty aligns with the issues in dispute (e.g., interventional cardiology for PCI-related delays, heart failure for prognosis).
• Clear instructions: Provide focused questions, relevant records, and assumptions to avoid ambiguity in the expert’s opinion.
• Proactive management: Facilitate the expert’s review of records and imaging, and address any queries promptly to avoid delays.
• Joint statement preparation: Brief the expert on key areas of dispute before their meeting with opposing experts to ensure productive discussions.

Specialist cardiology medico-legal assessment from an experienced consultant cardiologist expert witness can be pivotal in cases of this nature—particularly where causation, life expectancy, or subspecialty questions are in play. Early engagement with a suitably qualified expert ensures that the legal team is well-equipped to navigate the complexities of delayed MI claims under CPR Part 35.