Emergency surgery (decision to operate taken on the day of surgery)

Previous sternotomy

Preoperative renal failure (eGFR \<60 ml/min)

History of chronic non-anginal pain

Chronic pain medication other than paracetamol and non-steroidal anti-inflammatory drugs

Concurrent use of oxycodone, lorazepam, or ethanol.

Concurrent use of any drugs for neuropathic pain e.g. antiepileptics, antidepressants

Allergy to pregabalin, gabapentin or ketamine

Pregnancy

Limited understanding of numerical scoring scales

Previous participation in other trials investigating analgesic agents or any IMP in previous three months

Preventing Pain After Heart Surgery