The Health Products Regulatory Authority (HPRA) says an estimated 583 automated external defibrillators need urgent safety updates.
It says without these updates, the devices across five affected models may not work as intended in an emergency situation.
It adds that they may require a software upgrade, or the replacement of a component part within the defibrillator device.
"The number of devices which require updates has dropped by 22% compared to the same period in 2016", the HPRA says.
It is calling on all organisations and individuals in possession of an automated external defibrillators (AED) to check that their device is not one of the models affected.
This information may be found by looking at the dedicated AED webpage on the HPRA’s website, which includes essential information on safety notices published by the manufacturers of affected devices.
Anne Tobin, the HPRA’s medical devices vigilance manager, said: "This year, over 583 automated external defibrillators in Ireland require an urgent update, without which the devices may not perform in a life threatening emergency.
"We know that the majority of cardiac arrests occur outside of the healthcare environment, where these devices offer an important first response intervention.
"We would urge those in possession of a device which needs to be upgraded to contact the manufacturer and to organise the necessary updates as soon as possible; this action could be the difference between life and death for whomever next requires treatment with the AED."
Many Irish sporting venues, schools, hotels, restaurants, businesses and shopping centres now have the cardiac devices on their premises in case of emergencies.
The HPRA says all organisations with an AED on their premises should provide the manufacturer of their device with their correct contact details to ensure that the manufacturer can inform them of the need for safety upgrades if required.