Cardiac Causation in personal injury claims.

But-for test in myocardial infarction claims

• Clinical question Would the myocardial infarction have occurred but for the accident?
• Evidence reviewed Pre-accident GP records, troponin trends, angiogram findings, stress test results, cardiac risk factor profile.
• Expert duty The opinion states whether the accident was a necessary condition for the cardiac event, on the balance of probabilities.
• Worked example A claimant with stable angina suffers an STEMI shortly after a road traffic collision; the expert addresses whether plaque rupture was caused by the accident or would have occurred regardless.

Material contribution where pre-existing disease is present

• Legal principle Where multiple causes are present, the accident need only have made a material contribution to the injury for causation to be established.
• Clinical application The consultant identifies how the accident may have contributed to the cardiac event over and above the natural course of pre-existing disease.
• What the report says The report identifies the accident as a material contributor where the evidence supports it. Apportionment of damages between contributing causes is a question for the court.

Arrhythmias triggered by trauma or stress

• Common presentations Atrial fibrillation, ventricular tachycardia, bradyarrhythmia or supraventricular tachycardia after the accident.
• Causation question Distinguishing stress- or trauma-induced arrhythmia from coincidental onset in a claimant with structural heart disease.
• Key evidence Holter monitor reports, event recorder data, the temporal relationship between accident and arrhythmia onset.
• Test engaged Material contribution: did the accident precipitate an arrhythmia that would not otherwise have occurred at that point?

Myocardial infarction: plaque rupture versus natural progression

• Accident-induced MI Plaque rupture potentially secondary to physical exertion, blunt chest trauma or acute emotional stress.
• Pre-existing disease Claimants with known coronary artery disease may still succeed where the evidence shows the accident accelerated or triggered the event.
• Diagnostic anchor Angiogram findings (culprit lesion location, plaque morphology) and the troponin trend (timing and magnitude of rise).
• What the report addresses Whether the accident was a but-for cause of the MI or a material contributor where pre-existing coronary disease was present.

Procedural exclusion risk

Reports that fail to address the expert’s duty to the court, omit the declaration of truth, or lack independence may be excluded by the court under its case management powers. In cardiac causation claims this most often occurs where pre-existing disease has not been properly considered in the analysis.

Overstating or understating causation

Overstating causation — for example, ignoring pre-existing coronary artery disease that explains the cardiac event independently of the accident — and understating it — for example, failing to recognise that the accident materially contributed to an arrhythmia in a claimant with structural heart disease — both put the opinion at risk on cross-examination. The opinion is built on the evidence rather than the instructing party’s preferred conclusion.