The findings were presented at the British Cardiovascular Society (BCS) conference in Manchester.
The data shows that the risk of an STEMI-type heart attack were 13 per cent greater on a Monday compared to the average of other days.
Cardiologist Jack Laffan from the Belfast Health and Social Care Trust said at the conference: "We've found a strong statistical correlation between the start of the working week and the incidence of STEMI. This has been described before but remains a curiosity."
Laffan also considers it likely that the natural cycle of weeks, months and seasons has on our health.
He said: "Based on what we know from previous studies, it is reasonable to presume a circadian element".
Nilesh Samani, medical director at the British Heart Foundation, added: "This study adds to evidence around the timing of particularly serious heart attacks, but we now need to unpick what it is about certain days of the week that makes them more likely.
"Doing so could help doctors better understand this deadly condition so we can save more lives in future."