Heart attack or myocardial infarction (MI) is a life-threatening medical emergency due to a sudden obstruction of the blood supply to the heart muscle. Heart attack is usually caused by a blockage of coronary artery by a blood clot on background of coronary artery disease.
- Chest pain radiating to neck, jaw, shoulder and back; the pain has heavy, constricting an pressure-like character
- Strong anxiety and fear
- Dizziness and lightheadedness
The intensity of chest pain may vary and in some people, especially in the elderly and in diabetic patients the pain may not be present at all. Sometimes, the discomfort may resemble indigestion.
Heart attack is an emergency requiring a prompt treatment. If there is any suspicion on heart attack, call immediately ambulance. If available and the affected person is not allergic, it is advisable to chew a tablet of Aspirin, ideally in the strength of 300 mg.
The definitive treatment aims to remove the blockage in coronary arteries, restore the blood supply to the heart muscle and minimize the risk of recurrence. Patients with heart attack need a combination of medicines to achieve this, usually involving of aspirin, clopidogrel or ticagrelor, blood-thinning injection, beta-blocker and statin.
According to ECG (electrocardiogram), heart attacks are classified as STEMI or NSTEMI. Patients with ST elevation myocardial infarction, STEMI are normally treated by immediate coronary angioplasty (primary PCI, PPCI) which is a catheter procedure in which the blocked coronary artery is opened and usually secured with a stent, small metallic mesh. Patients with NSTEMI, non-ST elevation myocardial infarction are usually first stabilized with medication and coronary angiogram with subsequent angioplasty or less often bypass surgery follow after several days.
Causes of heart attack
Coronary artery disease (CAD) is the main cause of acute coronary syndrome, an umbrella term including heart attacks of STEMI and NSTEMI type and unstable angina. In CAD, coronary arteries that supply blood to heart become narrow due to atherosclerotic plaques. The plaques may rupture and become focus of sudden blood clot formation. The blood clot triggered by plaque rupture can complete block artery and cut off blood supply to a part of heart muscle which leads to myocardial necrosis (irreversible damage to the heart muscle tissue) and scar.
Heart attack may have life-threatening complications such as:
- Arrhythmias (ventricular fibrillation) - heart rhythm disorder when the heart is just fluttering without effective pumping; this leads to cardiac arrest, ie loss of consciousness and quick death if not promptly treated with defibrillation (electric shock to ‘jump start’ the heart)
- Cardiogenic shock - severe form of acute heart failure when damage to heart muscle is so extensive that heart is not able to pump enough blood into circulation
- Mechanical complications – rupture of the heart walls or muscles related to heart valves leading to acute regurgitation (dysfunction of the valves which can cause heart failure)
These complications are the leading cause of death and appear usually in the first hours and days after heart attack. Monitoring, prevention and prompt treatment of heart attack complications is one of the main tasks of coronary care unit (CCU). In some cases, sudden death may occur before patient reaches the hospital.
The duration and degree of recovery from heart attack is directly proportional to the amount of damage occurred to the heart muscle. Some people may recover within two weeks to join routine activities while others may need several months to fully recover. The aim of recovery is to:
- Implement lifestyle changes and healthy habits, learn to control risk factors
- Adjust and optimize medication to reduce risk of further heart attack
- Restore physical fitness with cardiac rehabilitation and exercise
The prognosis of heart attack depends on several factors:
- Type and severity of heart attack – amount of damage to the heart muscle
- Age – as you would expect, advanced age carries less favourable prognosis
- Time to the start of treatment – the shorter the better
- Presence of comorbidities (previous damage to the heart, diabetes, kidney disease, lung disease and other medical problems
Most people not only survive heart attack but quickly return to normal life and if their risk factors are under control, the prognosis is excellent.