What is a heart attack?
Cardiovascular disease (CVD) is one of the leading causes of death and disability globally, responsible for the death of approximately one-third of individuals in the world, predominantly coronary artery disease, heart attacks or stroke.13
A heart attack (also referred to as myocardial infarction or MI) is a potentially lethal emergency caused by restricted blood flow to the heart muscle and subsequent cell death due to deprivation of oxygen.10 Restricted blood flow and associated heart muscle damage are due to a disbalance between oxygen demands and supply.
This disbalance occurs due to restricted blood supply in associated blood vessels that supply the heart muscle, known as the myocardium. Blockage of the heart arteries with blood clots is the predominant cause of loss of appropriate blood circulation.
Approximately 95% of heart attacks occur secondary to coronary heart disease (CDH), the condition that obstructs heart (coronary) arteries, with cholesterol deposits, and plaques.6 The buildup of plaques inside heart arteries is called atherosclerosis. Rupture of the plaque deposits leads to the release of blood clots, these clots can potentially block the appropriate blood circulation to the heart muscle and initiate a heart attack.
In other, much less likely scenarios, myocardial infarction can occur without such blockage due to rare diseases (such as Kawasaki disease), physical trauma, spasm of the artery and prolonged deficiency in key nutrients and electrolytes.
Causes and risk factors of heart attack
The likelihood of developing heart disease is significantly increased in certain people.7
Common risk factors include:
- Increased age
- Family history
- Male sex
- High blood pressure
- High blood cholesterol
- High emotional stress
- Abdominal obesity
- Lack of physical activity
- An unbalanced diet, high in saturated fats
Signs and symptoms
Symptoms of a heart attack are versatile and vary slightly in women and men. Some of the core shared symptoms include chest pain, also called angina. Painful sensation usually lasts around 15 minutes and is due to the inability of the heart to maintain its workload because of insufficient oxygen supply. It starts in the chest and gradually spreads to other parts of the upper body, often to the arms, neck, shoulder, waist and back.7 Pain levels vary majorly, while some experience only mild discomfort and heaviness, others experience intolerable pain.
Other common symptoms include sweating, heart palpitations, shortness of breath, nausea, dizziness, coughing and stomach discomfort.4
A combination of these symptoms must immediately raise concern, if a heart attack is suspected appropriate actions must be taken immediately (such as calling 999).
Occasionally, heart attack incidence can be mistaken for indigestion or Takotsubo cardiomyopathy (broken heart syndrome). The latter is a condition caused by a surge of stress hormones, which occurs due to high emotional or physical stress.
How long can a heart attack last?
The timing of myocardial infarction varies significantly. Some episodes last a few minutes after which blood flow is promptly restored, causing only mild to no symptoms, and therefore can even be silent.2
While usually symptoms of myocardial infarction are short-lived, in some they tend to persist for multiple hours. These symptoms can occur periodically over the span of multiple hours, becoming milder over time and then coming back again. Animal studies show that cell death of heart muscle is not immediate, it takes at least 20 minutes from the onset of myocardial infarction for cells to start degenerating, while complete death of all myocardial cells occurs roughly after 5-6 hours, resulting in cardiac death.2
Society for Cardiovascular Angiography and Interventions reports the window of approximately 90 minutes starting from the first onset of heart attack, in which the appropriate medical help and restoration of blood flow can prevent critical damage to the heart muscle.14
The World Health Organization (WHO) uses consensus ECG markers and other biological blood findings to define myocardial infarction from other coronary heart conditions.4
- Assessment of electrocardiographic (ECG) Q waves: clinical test which allows detection of structural abnormalities of the tissue, inadequate heart blood pumping capacity, irregularity of heart rhythm.
- Imaging and Blood tests to look for structural and biochemical clues that will help them establish the nature and cause of the disease, respectively.
Scientists are constantly looking for even more sensitive and precise blood tests and imaging techniques to allow identification of the smallest levels of tissue abnormalities (indicative of very low-scale clots blockages occurring) to prevent the onset of a full-scale heart attack.1 Additionally, it is well established that the incidence of heart disease is particularly affected by the genetic predisposition of the individual and family history, thus geneticists are in the process of identifying genes responsible for CHD, making it possible to run genetic screening tests in the future to allow prophylaxis of the serious cardiovascular disease.
Risks of not treating a heart attack
Prolonged oxygen deprivation to the cells of the myocardium significantly disrupts the blood pumping sequence of the heart and affects blood flow to the rest of the body.
For instance, the inability to pump blood effectively can cause abnormal heartbeats, a condition is known as arrhythmia, which in turn are the primary cause of sudden cardiac arrest (sudden stoppage of the heart).1 Myocardial cell death of various areas can cause all sorts of heart valve problems, depending on which part of the heart muscle is affected, while severe overall damage to the tissue can cause cardiogenic shock. Complete cardiac death leads to loss of blood pumping ability around the body, known as heart failure.
Complications of an untreated heart attack
According to the National Health Service (NHS), deaths linked to heart attacks are often due to MI complications, either immediately or shortly after having a heart attack. Interestingly, there is a strong correlation between the duration of an untreated heart attack and its severity.
Treatment for a heart attack
Management of this condition is mainly centred around restoration of the blood flow to the heart muscle as soon as possible. This can be achieved by a variety of medical treatment options varying from the introduction of appropriate medication to surgical intervention.12
Drugs are administered both to mitigate the occurrence of heart attacks in highly predisposed people (for example those struggling with poorly managed diabetes) and treat its consequences.13
- Antihypertensives: drugs that treat high blood pressure by various means
- Statins: drugs targeted at reducing high cholesterol levels by preventing its production from the liver
- Anticoagulants: drugs that prevent blood clots formation, thin the blood and allow its easier flow through the vessels
- Platelet inhibitors: drugs such as Aspirin, which are used to stop the clumping of platelets
- Thrombolytic intravenous (IV) drip: drugs introduced directly into the circulation to dissolve blood clots present within blood vessels. This type of medication is used within the first 12-hours of the heart attack
- Beta-blockers: drugs that slow down the heart rate and cardiac output, thus decreasing heart muscle output
Additionally, other drugs are targeted to ease and reverse symptoms associated with MI.
- Supplementary oxygen is used to re-establish normal breathing and increase oxygen supply to deprived tissues.
- Antiarrhythmic medications reverse any disruption to normal heart rhythms.
- Painkillers are used to soothe unbearable chest pain.
Surgical treatments on the other hand include the following:
- Coronary angioplasty and stents: surgeons introduce synthetic balloon-like structures inside the coronary artery to improve blood bypass and supply to the heart. A stent is a stainless steel mesh positioned within the artery to support normal blood flow.
There are numerous other surgical options, including the most recent implantable medical tools that are targeted treatment of certain kinds of heart attacks.
Rehabilitation from a heart attack will vary naturally in each individual, it can last from a couple of weeks to considerably longer periods. It is important to avoid rushing this process.11
The aim of rehabilitation from coronary disease is to ensure that a person can go back to living their normal life as soon as possible.
Hospital staff will provide patients with physical and mental support to ensure that the rehabilitation process is safe and effective. Shortly after leaving the hospital patients will be expected to continue their recovery at home, which involves following professional health advice. It is important that during this time an individual takes appropriate medicines and has regular check-ups with their doctor. It is common for patients to experience anxiety and low mood, in this case, GP must be notified to provide additional mental health support, such as counselling.3
Preventing heart problems
Although we have little control over certain risk factors, such as ageing, male gender assigned at birth, or genetic predisposition. Many scientists believe that the incidence of heart attack can be prevented by introducing certain lifestyle changes.
It is essential to keep track of your health and wellness, both physically and mentally.
Scheduling regular check-ups can help you control and manage current health conditions as well as catch very early silent signs of cardiovascular abnormalities.5
Taking regular moderate exercise and sticking to a balanced diet rich in fibre and essential vitamins, but low in saturated fat - is key to mitigating risk and establishing control over CHD.
It is very important to completely give up tobacco smoking, since it significantly increases the blood pressure and heart rate, leading to an increased risk of CVD among other pathologies.5
Appropriate and regular use of medication is essential to prevent and treat heart attacks.
When to seek emergency medical help
Think quick…act immediately.
Red flags are:
- Persistent chest pain or discomfort
- Pain spreading to the left or right arm
- Pain spreading up to the neck and jaw
- Shortness of breath
- Call 999 for an ambulance
- Get the person in a sitting position, stay with them and keep them calm
- While waiting for the ambulance, give the person an aspirin tablet (300mg) to chew. (IMPORTANT NOTE: unless the person is allergic to aspirin if you do not know if person might be allergic skip this step)
Heart attacks are major killers, however according to the statistics, the deaths from myocardial infarctions in the UK fell by about 50% between 2002 and 2010, due to improved prevention and treatment options.8,9 Therefore it is important to be aware of the risks, maintain a healthy lifestyle and seek help immediately if heart attack is suspected.
- Lüscher T. Myocardial infarction: mechanisms, diagnosis, and complications. European Heart Journal. 2015;36(16):947-949.
- Cunha J. How Long Do Heart Attacks Last? Symptoms & Recovery Time [Internet]. eMedicineHealth. 2022 [cited 24 July 2022]. Available from: https://www.emedicinehealth.com/how_long_do_heart_attacks_last/article_em.htm
- Elks C. Cardiac rehabilitation [Internet]. Bhf.org.uk. 2022 [cited 23 July 2022]. Available from: https://www.bhf.org.uk/-/media/files/publications/heart-conditions/his23_1117_cardiac-rehab_a6.pdf?rev=b9712d52271e452b9f9160d537143823
- Bruyninckx R, Aertgeerts B, Bruyninckx P, Buntinx F. Signs and symptoms in diagnosing acute myocardial infarction and acute coronary syndrome: a diagnostic meta-analysis. British Journal of General Practice. 2008;58(547):e1-e8.
- Zafari A. Myocardial Infarction: Practice Essentials, Background, Anatomy [Internet]. Emedicine.medscape.com. 2022 [cited 23 July 2022]. Available from: https://emedicine.medscape.com/article/155919-overview
- Heart Attack: What Is It, Causes, Symptoms & Treatment [Internet]. Cleveland Clinic. 2022 [cited 23 July 2022]. Available from: https://my.clevelandclinic.org/health/diseases/16818-heart-attack-myocardial-infarction#management-and-treatment
- Ornato J, Hand M. Warning Signs of a Heart Attack. Circulation. 2014;129(11).
- World Health Organisation (WHO). Cardiovascular diseases (CVDs) [Internet]. Who.int. 2022 [cited 23 July 2022]. Available from: https://www.who.int/en/news-room/fact-sheets/detail/cardiovascular-diseases-(cvds)
- How heart attacks became less deadly - Harvard Health [Internet]. Harvard Health. 2022 [cited 23 July 2022]. Available from: https://www.health.harvard.edu/healthbeat/how-heart-attacks-became-less-deadly
- Heart Attack - What Is a Heart Attack? | NHLBI, NIH [Internet]. Nhlbi.nih.gov. 2022 [cited 23 July 2022]. Available from: https://www.nhlbi.nih.gov/health/heart-attack
- Recovering from a heart attack [Internet]. nhs.uk. 2022 [cited 23 July 2022]. Available from: https://www.nhs.uk/conditions/heart-attack/recovery/
- Treatment of a Heart Attack [Internet]. www.heart.org. 2022 [cited 23 July 2022]. Available from: https://www.heart.org/en/health-topics/heart-attack/treatment-of-a-heart-attack
- Thygesen K, Alpert J, White H. Universal Definition of Myocardial Infarction. Journal of the American College of Cardiology. 2007;50(22):2173-2195.
- SOCIETY FOR CARDIOVASCULAR ANGIOGRAPHY AND INTERVENTIONS. Nationwide Study Finds Significant Decline in Treatment for Heart Attacks During Pandemic | SCAI [Internet]. Scai.org. 2022 [cited 24 July 2022]. Available from: https://scai.org/nationwide-study-finds-significant-decline-treatment-heart-attacks-during-pandemic