Symptoms

Myocardial infarction (MI) is not always accompanied by the onset of sudden, intense symptoms. In contrast, most often it starts slowly, with mild pain or discomfort.

The most important signs that can indicate an acute MI are:^1,2,3

• Chest discomfort (uncomfortable pressure, squeezing, constriction or pain) usually in the centre of the chest, but also radiating to neck, jaw, stomach, shoulder, back and arms (typically left arm).
• Dizziness
• Syncope due to an arrhythmia or severe hypotension
• Tachycardia due to sympathetic nerve activation
• Bradycardia in patients with inferior STEMI due to vagus nerve inactivation
• Cardiogenic shock due to impaired myocardial function
• Shortness of breath or fatigue
• Breaking out in a cold sweat, nausea/vomiting or light-headedness

Each MI can have different signs but the severity of symptoms and the final outcome in patients are not directly related. If the patient has no symptoms or atypical symptoms, the MI may be categorised as ‘silent’.³ In some (but not all) cases, silent MI may be later identified and referred to as ‘unrecognised MI’. Unrecognised MI is a common and clinically significant event.