PHOEBE CHARMAINE PICKERING v CAMBRIDGE UNIVERSITY HOSPITALS NHS FOUNDATION TRUST

Where a patient with atrial fibrillation presents with an acute systemic embolic event, an unstable atrial clot and a substantial risk of further embolisation, immediate anticoagulation may be required to prevent further clot propagation and embolic stroke. The absence of direct randomised trials in an acute, high-risk setting does not prevent causation being established on the balance of probabilities. Evidence from related clinical contexts may be used where the factual and physiological similarities are properly assessed. Heparin can act rapidly by preventing new clot formation, limiting propagation and allowing natural thrombolytic processes to reduce and stabilise an existing clot. On the evidence, treatment over 67 hours would probably have prevented the subsequent stroke.

The claimant, who had longstanding atrial fibrillation, attended hospital after suffering intermittent right-leg ischaemia caused by an embolus from a clot in the left atrium or left atrial appendage. She had not been taking therapeutic anticoagulation. The defendant admitted that it should have administered low molecular weight Heparin before her discharge but failed to do so. The claimant suffered a major left-sided stroke approximately 67 hours later.

The trial therefore concerned causation: whether, had Heparin been administered and followed by therapeutic anticoagulation, the claimant would probably have avoided the embolus and stroke.

1. Judgment for the claimant. The defendant admitted breach of duty in failing to administer immediate Heparin and admitted that the claimant would have accepted the advice to commence treatment.
2. The relevant duty concerned protection against the foreseeable risk that a further embolus would leave the unstable clot in the left atrial appendage and cause a stroke or other serious ischaemic event. The claimant was at high risk of further embolisation after the earlier limb embolus.
3. On the balance of probabilities, Heparin would have begun acting within approximately one to three hours. It would have prevented new clot formation, limited propagation of the existing clot, and assisted the body’s natural processes in dissolving, stabilising, organising and adhering the clot to the atrial wall.
4. The court preferred Professor Mehta’s evidence to that of Dr Patel. The peri-operative bridging studies relied on by Dr Patel involved materially different patients, who had generally received anticoagulation for several weeks before surgery and were unlikely to have had a fresh, friable atrial clot. Those studies did not establish that Heparin was ineffective in the claimant’s acute circumstances.
5. The evidence from the Collins et al and Konstantinides et al studies, together with the experts’ agreed evidence and clinical reasoning, supported the conclusion that the clot would have reduced substantially during the relevant period and become less friable and less likely to embolise. The lack of ethically feasible randomised trials in such an emergency did not prevent a finding on the balance of probabilities.
6. Had Heparin been given for the first three to seven days, followed by Warfarin or a modern oral anticoagulant, the claimant would probably have avoided the embolus on 27 September 2015 and consequently the stroke. Judgment was entered for the claimant.

First-instance clinical negligence claim issued in January 2020. No appeal or earlier judgment is stated.