Acute Coronary Syndrome

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What Is Acute Coronary Syndrome?

Acute Coronary Syndrome is a set of symptoms and signs associated with an abrupt reduction of blood flow to the heart, causing damage to the heart muscle and improper functioning.

Alternate name

  • ACS

Is this a medical emergency?

ACS is a medical emergency and requires immediate investigation, and management to restore the blood flow to the heart, and prevent further complications and damage to the heart tissues.

Types of this condition

The acute coronary syndrome includes three major kinds of coronary artery disease which are:

  • Unstable Angina: Which is angina that is occurring for the first time, or if there is a change from a previously diagnosed stable angina with the symptoms coming on at rest or minimal exertion, are more frequent and severe, and last longer.
  • Non-ST segment Elevation Myocardial Infarction (NSTEMI): Which is a heart attack that does not show major changes in the ECG, as the blockage of the blood supply may be minimal or momentary.
  • ST-Segment Elevation Myocardial Infarction (STEMI): This is a heart attack that shows marked changes in the ECG, as the blockage of blood flow is significant, longer-lasting, and affects a large area of the heart muscle.


The most significant cause of acute coronary syndrome is the formation of a clot after atheromatous plaques or fatty deposits break or rupture inside the coronary arteries, the blood vessels that supply oxygen and nutrient-rich blood to the heart muscle. The blockage or reduction of blood supply due to the presence of the clot causes damage and death of the cells of the heart muscle leading to a heart attack, or improper functioning of the heart muscle leading to unstable angina.

Risk factors

Some of the major risk factors for acute coronary syndrome include:

  • Family history of heart disease
  • Aging
  • Lack of exercise
  • Smoking
  • Unhealthy eating habits
  • Being overweight or obese
  • High blood cholesterol levels
  • High blood pressure, or a history of high blood pressure
  • Diabetes or high sugar levels during pregnancy

Triggering factors

Although the acute coronary syndrome can occur abruptly, at rest, and at any time, research has shown that it is more common during morning hours, and it may be triggered by:

  • Vigorous activity
  • Anger
  • Emotional stress
  • Sexual activity
  • Cocaine
  • Air pollutants

Symptoms & signs

An acute coronary syndrome is sudden in onset and the primary symptom is chest pain. The pain is usually described as a tightness or pressure over the chest that may or may not radiate to the left arm and/or the angle of the jaw on the left side. It is also important to note that pain may be absent in some cases especially in women or in diabetics. In addition to pain, there is a general feeling of being unwell and may be accompanied by:

  • Sweating
  • Indigestion, a feeling of fullness
  • Nausea and vomiting
  • Shortness of breath
  • Cough
  • Wheezing
  • Fainting or light-headedness
  • Generalized weakness
  • Anxiety


Preliminary investigations for acute coronary syndrome include:

  • ECG: It is the primary investigation that is done to establish a preliminary differentiation between a heart attack and unstable angina.
  • Blood tests: Are done to measure the levels of cardiac markers such as Troponin I or T, and the presence of these markers helps to differentiate between a heart attack and unstable angina.

Based on the results of the ECG and the cardiac markers, further tests may also be done and these include:

  • Coronary Angiogram: A minimally invasive diagnostic imaging procedure that is used to visualize the coronary arteries and locate the site and size of the blockage.
  • Echocardiogram: An imaging test that utilizes ultrasound waves to assess the functioning of the heart.
  • Myocardial Perfusion Imaging: A procedure is done using radioactive isotopes on a PET scan or SPECT scan to study the blood flow to the heart muscle during stress or increased activity.
  • CT Angiogram: A CT scan study of the coronary arteries done after injecting a high contrast dye containing iodine.


Diagnosis of the acute coronary syndrome and its cause is based on the interpretation of the results of the investigations.

  • STEMI: Changes in the ECG that show an elevation of the ST segment along with the presence of cardiac markers.
  • NSTEMI: The presence of cardiac markers and the absence of ST-segment elevation in the ECG.
  • Unstable angina: The absence of cardiac markers and any significant changes in the ECG.

Treatment options

Treatment for the acute coronary syndrome is based on whether it is a:

  • STEMI: This indicates there are significant blockage and heart tissue damage.
  • NSTEMI: This indicates there is a partial or a temporary blockage with heart tissue damage.
  • Unstable angina- Where there are no ECG changes or tissue damage.

The treatment is also based on the level of risk for immediate future complications in the case of NSTEMI and Unstable Angina. In all of these cases, the treatment is aimed at relieving pain, restoring the blood flow to the heart at the earliest, and preventing further tissue damage.

A. Medical treatment

Medications for acute coronary syndrome for immediate relief as well as extended use include one or a combination of the following:

  • Thrombolytics: To help dissolve the clot and restore the blood flow. It is advisable to administer via injection within 30 minutes of the onset of symptoms.
  • Nitroglycerin: To improve the blood flow through the arteries.
  • Antiplatelet drugs: To prevent the formation of clots within the arteries.
  • Angiotensin-Converting Enzyme (ACE) Inhibitors: To increase the blood flow and decrease the blood pressure, thereby decreasing the workload of the heart.
  • Angiotensin Receptor Blockers: To reduce the blood pressure and the workload of the heart.
  • Beta-Blockers: To reduce the blood pressure and the workload of the heart.
  • Statins: To reduce the amount of cholesterol in the blood and to stabilize existing plaques and preventing them from rupturing.

B. Surgical treatment

Surgical intervention may be required in some cases of ACS, especially when the diagnosis of STEMI has been established. The surgical treatment may include:

  • Angioplasty and stenting: Which is a minimally invasive interventional cardiology procedure such as percutaneous coronary interventions are done in which a balloon is guided through a catheter to unblock or widen the arteries and besides, a tiny tubular metal mesh called a stent is placed inside the artery to act as a support and keep the artery open. It is advisable to perform this procedure within 90 minutes from the onset of symptoms.
  • Coronary Bypass Surgery or Coronary Artery Bypass Grafting (CABG): Is a procedure where the blockage is significant and an arterial graft is used to bypass the blocked artery and restore the blood supply to the heart.

Preventive measures

Maintaining a healthy lifestyle and habits is essential in the prevention of acute coronary syndrome specifically and heart disease in general. Some of the measures that need to be taken include:

  • Quitting smoking
  • Eating a healthy diet that includes fruits, vegetable, lean meats, and low-fat dairy
  • Getting regular exercise and staying physically fit
  • Maintaining proper body weight
  • Monitoring and keeping blood cholesterol levels under control
  • Monitoring and controlling blood pressure levels
  • Reducing mental and emotional stress
  • Keeping a check on alcohol consumption


The acute coronary syndrome may lead to:

  • Hypotension, heart failure, and shock
  • Pericarditis
  • Post-myocardial infarction syndrome (Dressler's syndrome)
  • Myocardial rupture
  • Ventricular aneurysms
  • Abnormal heart rhythms such as atrial fibrillation, ventricular tachycardia, ventricular fibrillation leading to cardiac arrest


The prognosis of Acute Coronary Syndrome depends on several factors, based on which the mortality and other complications can be predicted in patients with NSTEMI and Unstable Angina, in whom the risk of complications is significantly more than in STEMI cases. The TIMI score which takes into account various factors predicts a mortality risk of 40% or more in patients with a score equal to 6 and above. The factors that are taken into consideration include:

  • Age>65 years
  • Usage of aspirin
  • Number of episodes of angina
  • ST-segment changes on ECG
  • Family history of heart disease
  • Elevated serum cardiac markers
  • Hypertension
  • Smoking history
  • Diabetes
  • Cholesterol levels

Similarly, the GRACE and Killip Classification is used to predict mortality and risk of complications in ACS. Cardiac biomarkers such as natriuretic peptide and MCP-1 also are indicators of risk of death and adverse outcomes after ACS.

When to contact the doctor/How to identify complications?

ACS is a medical emergency, and it is advisable to get immediate medical attention by contacting a doctor in the event of chest pain with or without the other accompanying symptoms. Early investigations and intervention will reduce the likelihood of further complications and death.

Indications for hospitalization if required

In the event of an ACS, most people would require hospitalization until all the investigations are completed and the individual is stabilized. Only in cases where the cardiac biomarkers are significantly low with no adverse ECG changes, and a low TIMI score the person may be discharged as the risk of myocardial infarction or heart attack is considered low.

Screening methods

In symptomatic high-risk individuals, a regular cardiovascular risk assessment needs to be done.

Suggested clinical specialists/Departments to consult for this condition

The Emergency Department will be the first medical department to attend to this condition and will be followed up and treated by the Cardiology Department.  

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