A man who died in prison of cardiac failure was taking five prescribed torsadogenic medicines at the time.

A NSW coroner found it was likely that morbid obesity and cardiomegaly, along with the concurrent use of these medicines, caused the cardiac arrythmia that killed 37-year old Edward Haenga at a Sydney prison just months before his release date.

But his medical regime inside NSW’s corrections system was “not clinically optimal”, the coroner said.

The father-of-three had been in prison for almost 16 years and was due for release in December 2013.

He was a complex patient with pain disorder, hepatitis C, osteoarthritis, bipolar disorder and PTSD, and a history of illicit drug abuse.

Many of these health problems were the result of suffering third degree burns to 70% of his body in a house fire in 1993, the court heard.

Weighing 199kg, Mr Haenga was at risk of metabolic syndrome and was meant to attend monitoring but rarely did.

The concurrent prescribing of five drugs that can cause QT interval prolongation – amisulpride, escitalopram, methadone, quetiapine and pericyazine – put him at risk of fatal cardiac arrhythmia, the court heard.

One of these medications, quetiapine, was de-prescribed but recharted through a medical error.

The coroner said this could have been picked up in multidisciplinary meetings, or at clinical handover to Long Bay, however neither practice was in use in the corrections system at the time.

Three medical experts told the court that torsadogenic drugs are not recommended to be prescribed together.

The coroner also noted regular ECG tests would have been beneficial, but this was not addressed in medical guidelines on metabolic syndrome at the time.

The coroner made several recommendations to Justice Health and the private prison where Mr Haenga lived between 2010-13, including that Justice Health add information on the benefits of including ECGs in metabolic monitoring.

Read the report here.