Queensland Premier Annastacia Palaszczuk has confirmed the probe amid reports the young women with RHD unsuccessfully tried to seek treatment at Doomadgee Hospital in the state's northwest.
The women - aged 17, 18 and 37 - died after being turned away by the emergency department, ABC's Four Corners says.
One of the women was supposed to receive weekly check-ups and urgent surgery but instead was forced to visit the hospital's emergency department 12 times in less than two months seeking pain relief, the ABC program says.
"The Health Minister has raised this with me. We know there has been some tragic cases and our thoughts are with the families of those loved ones," the premier said of the fatal RHD cases on Tuesday.
"My advice from the Health Minister is that these cases are currently under investigation by the North West Hospital and Health Service and the coroner."
The Queensland Health Ombudsman is also reportedly investigating whistleblower complaints about the hospital's management practices and standards amid claims it is cutting costs at the expense of patient care.
Health Minister Yvette D'Ath said she expected any allegations raised about the Doomadgee Hospital to be probed.
"These are tragic cases and clearly the patients have been badly let down," D'Ath said in a statement to Four Corners.
"All cases are under investigation by North West Hospital and Health Service and I expect to be informed of the findings.
"I would also expect any allegations about the standard of care delivered at Doomadgee Hospital to be investigated."
Liberal National Party leader David Crisafulli said the hospital's treatment of the Doomadgee women was a "national disgrace".
The Premier said moves were already in place to address RHD in remote communities following the release of a $7.3 million state government plan last week.
She said the "Australian first" strategy would improve early prevention and care for First Nations people living with the disease.
"The Rheumatic Heart Disease Strategy...includes $2.8 million in specific actions in 10 communities including Doomadgee," she said.
The plan also aims to reduce the impact of acute rheumatic fever (ARF).
In Queensland, Aboriginal and Torres Strait Islander people make up 73 per cent of the 3,089 patients on the RHD register.
Another 10,212 ATSI people are expected to have ARF or RHD by 2031, the state government says.
RHDAustralia has urged the Commonwealth to follow the Queensland government's lead.
The federal government funded RHD Endgame Strategy - a blueprint to eliminate the disease in Australia - was released in 2020.
RHDAustralia director Vicki Wade says the Commonwealth must start implementing the strategy now, urging the federal government to inject $40 million over the next three years.
"The nation needs to stand up and do something about this tragic and totally preventable cause of death before more of our young people are killed," she said.
