Dr Chan said the gunshot wounds to his inner thigh and scrotum - inflicted when the gun carried by an emotionally disturbed constable went off during a scuffle in an underpass in Aberdeen on September 6 last year - had caused him no 'irreversible damage'.

The expert witness was giving evidence after Wong's family suggested that mental stress suffered after the shooting had contributed to his collapse. They said his health had deteriorated and he was always tired.

After studying the sergeant's medical history, Dr Chan rejected their suggestion, saying the hour-long workout on the track had caused blood to surge to the clogged coronary arteries, leading to an acute cardiac attack.

A postmortem examination, which found the cause of death to be a heart attack resulting from coronary atherosclerosis, revealed that one of Wong's prime coronary arteries and two smaller ones had been blocked by 50 to 95 per cent.

After collapsing he was taken to Queen Mary Hospital, where his heart failed five times.

Dr Chan said: 'The gunshot didn't leave him with any irreversible damage.

'After the gunshot, his blood pressure and heart rate remained stable, he recovered well and quickly from a small operation, and it was almost four weeks before the collapse.'

He said chronic hypertension, which had not been carefully managed, had signalled hidden risks and his workout at the sports ground was the trigger. Even if he had worried about his career, the 'worries did not constitute any direct or indirect relation [to his death]'.

Pathologist Ying Ho-wan said the gunshot wound might have affected the sergeant's health, but this was unrelated to his later collapse.

'If stress [from the gunshots] did play an important role, it would have shown at the moment he was shot. His heart would have been affected in September.'

The inquest continues today before Coroner Michael Chan Pik-kiu.