What do these subtle early warning signs look like?

Dr Xu says the majority of patients experience somewhat typical symptoms, such as radiating chest pain, heaviness or discomfort, heart palpitations, cold sweats, and shortness of breath.

Others — women more so than men — will experience some atypical symptoms as well, which may include fatigue, a general sense of unease, vague discomfort, back or abdominal pain and declining stamina, he says.

“Both types of symptoms can be experienced months before an actual heart attack occurs,” he warned.

Research suggests one particular symptom is more common than others.

A study published in Cureus found chest pain to be the most common sign of a heart attack, with 68 percent of people experiencing it prior to the event itself.

Almost half (32 percent) experienced the symptom more than one month before the potentially deadly event.

This was followed by chest heaviness at 44 percent, palpitations at 42 percent, shortness of breath at 34 percent, and chest burning at 27 percent. Unusual fatigue in 23 percent and sleep disturbance in 22 percent of the patients were also reported.

How to respond

The NHS says to call 999 immediately if you think you might be having a heart attack.

The faster you act, the better your chances.

“If aspirin is available and you are not allergic to it, slowly chew and then swallow an adult-size tablet (300mg) while you wait for the ambulance,” advises the health body.

Aspirin helps to thin your blood and improve blood flow to your heart.