It is reported the death rates from heart attacks are almost double the national average in six small hospitals.
According to the Sunday Business Post, the combined death rate at Roscommon County Hospital, Bantry General and South Infirmary Victoria in Cork, Ennis Hospital, St John's in Limerick and St Michael's in Dublin was 12.2%.
That compared with a national average of just over 6.6%.
The Department of Health has said it does not use small numbers as an indicator, as they may be unreliable.
Independent TD for Roscommon/South Leitrim Denis Naughten said the HSE should release the figures for every hospital.
"What we need is a full breakdown of the figures for each hospital, because it could be the case that you have one or two outliers, and every small hospital is being tarnished with the same brush," he said.
"There are examples of good practice and they need to be replicated right across the system."