HBDHB recorded a total of 18 adverse events over that period.
They included a failure to communicate the deterioration of a septic patient and escalate level of care. Delay in the flight transfer of the patient resulted in their death.
The third patient death involved a skin assessment not undertaken in timely manner, and the patient has since died.
Chief Medical and Dental Officer Robin Whyman said although there were fewer events reported this year, compared with 24 the previous year, a number of priority areas had been identified for ongoing training and educating of staff to better manage deteriorating and bedridden patients.
He said an early warning score system to identify patients quickly if they began to deteriorate, while in hospital, had been put in place.
"The work is being led by senior clinical staff and we are pleased with the progress."
An investigation into the cardiology patient's death is still in progress and is scheduled to go before a Clinical Risk Event Advisory Group in December.
In the past few years the district health board had invested in more staff dedicated to reporting, investigating and responding to patient events, Whyman said.
"We are always mindful, as we report these events each year, that there is a person and their family/whānau behind each of the numbers.
"The clinicians involved in these cases have a strong clinical interest to ensure each case is a learning and that there is transparency with the patient and their family during the process."
Whyman said although there were 18 adverse events reported for Hawke's Bay they should also be placed in context against the 33,256 people who were admitted to hospital, 51,129 who attended the emergency department and the 135,758 people who attended outpatient clinics in the 2018-19 year.
Across New Zealand a total of 312 deaths were reported to the Health Quality & Safety Commission in 2018/19.
Of these deaths, 209 were suspected suicides reported from the Mental Health and Addictions sector, and 103 were from across the rest of the health sector.
However, these deaths were not necessarily directly related to the adverse event.
International studies show 10–15 per cent of hospital admissions can be associated with an adverse event, although about half of the events occurred before admission to hospital, in other health settings.
Some adverse events are known complications of treatment and are not preventable.