The two can feel similar because the heart and oesophagus sit close together. Heartburn is more likely if symptoms come after meals, worsen lying down, ease when you sit up or take an antacid, and bring an acid taste in the mouth.
Warning signs pointing to the heart include chest pressure or squeezing rather than burning, pain radiating to the left arm, neck, jaw or back, cold sweat, nausea, shortness of breath, light-headedness, or symptoms triggered by exertion.
Because a heart attack can be fatal and is not always obvious, never try to diagnose yourself when symptoms are new, severe, or different from your usual heartburn. Call your local emergency number immediately if you have any of the heart warning signs. It is always safer to be checked and told it was only reflux than to miss a cardiac event.