Hartford Hospital

Conditions In Full

Search for

Acute Coronary Syndrome

(ACS; Unstable Angina)

En Español (Spanish Version)

Definition | Causes | Risk Factors | Symptoms | Diagnosis | Treatment | Prevention


Acute coronary syndrome (ACS) is a term that describes symptoms related to poor blood flow to the heart muscle that lead to a heart attack. This results in chest pain or angina pectoris. ACS is a very serious, life-threatening condition. If you think you have ACS seek immediate medical treatment.


ACS is caused by a sudden blockage of the coronary arteries. These blood vessels carry blood to the heart muscle. The blood flow to the heart muscle is either greatly reduced or completely blocked. This leads to heart muscle damage or death from a heart attack.

The narrowing most often happens from years of plaque build-up in an artery. This is called atherosclerosis. Blood clots may often cause of the narrowing arteries.

Coronary Artery

Nuclus factsheet image
Copyright © Nucleus Medical Media, Inc.

Risk Factors

Risk factors that increase your chances of developing acute coronary syndrome include:

  • A family history of heart disease
  • You are a man over 45 years old or a woman over 55 years old
  • Being overweight or obese
  • Smoking
  • High cholesterol, especially high LDL ("bad") cholesterol, high triglycerides, and low HDL (“good”) cholesterol
  • High blood pressure
  • Diabetes
  • Being sedentary
  • Having angina, a previous heart attack, or other types of coronary artery disease


ACS is very serious. It requires immediate medical treatment. Contact your doctor if you experience any of these symptoms:

  • Angina
    • chest pain, pressure, tightness, burning, or other discomfort that may last a few minutes, go away, and then come back
    • often occurs after physical exertion, emotional stress, or eating a large meal
  • Unstable angina
    • often occurs at rest, while sleeping, or with very little exertion
    • can last 30 minutes or longer
  • Pain or discomfort in one or both arms, shoulders, the back, the neck, jaw, or stomach
  • Shortness of breath that accompanies chest pain can occurs before it starts
  • Feeling light-headed or dizzy
  • Nausea and vomiting
  • Sweating


Your doctor will ask about your symptoms and medical history. A physical exam will be done. If you suspect ACS, call an ambulance. At the hospital, tests may include the following:

  • Electrocardiogram (ECG or EKG)
  • Nuclear heart scan—radioactive tracers outline heart chambers and major blood vessels leading to and from the heart
  • Cardiac catheterization —can determine pressure and blood flow in the heart's chambers, collect blood samples from the heart, and examine the arteries of the heart by x-ray
  • Blood tests to measure different enzymes that are released when cells in the heart muscle die, including:
    • Troponin test
      • considered the most accurate test
      • can determine if a heart attack has occurred and how much new damage was done to the heart
    • CK or CK-MB test—measures creatine kinase (CK) in the blood
    • Myoglobin test—checks for the presence of myoglobin in the blood
  • Your doctor may need detailed pictures of your heart. These can be made with:
    • Coronary angiography —produces images of blood flow through the heart to will show where there are blockages are
    • Echocardiogram —to create a moving picture of your heart
    • Chest x-ray —images of the inside of the chest to assess heart size and show lung congestion and the presence of pneumonia


If you are having a heart attack, doctors will:

  • Work quickly to restore blood flow to the heart
  • Closely monitor vital signs to detect and treat complications
To restore blood flow, the main treatments are:

  • Aspirin are given to all patients suspected of having acute coronary syndrome.
  • Anti-ischemic drugs, such as nitroglycerin are used to help relieve chest pain.
  • Beta blockers are given to slow the heart rate so it does not use too much energy.
  • Thrombolytic drugs are used to dissolve blood clots. When given soon after a heart attack begins, these drugs can limit or prevent permanent damage to the heart. To be most effective, they need to be given within one hour after the start of heart attack symptoms. Some thrombolytic drugs are:
    • Streptomycin
    • TPA
  • Platelet inhibitors keep the blockage from getting worse:
    • Eptifibatide
    • Tirofiban
    • Glycoprotein IIb/IIIa receptor antagonist
  • Angioplasty —a catheter is inserted into a blocked artery. A balloon is inflated and deflated. This will allow blood to flow again. A stent may be placed.
  • Coronary artery bypass surgery —arteries or veins are taken from other areas in your body. They are used to bypass the blocked arteries in your heart.
  • Oxygen is given to all patients.

Treating ACS with angiography and revascularization (restoring blood flow to the heart) may reduce the rate of being hospitalized again. But, the surgery may not reduce the rate of death or heart attack.


To help reduce your chances of getting ACS, take the same heart-healthy lifestyle steps used to prevent other forms of coronary artery disease such as:

  • Eating a well-balanced diet that is low in saturated fats. The diet should also be rich in fruits, vegetables, and whole grains.
  • Exercising regularly.
  • If you smoke, quit.
  • Manage your diabetes, blood pressure, and cholesterol. This can include lifestyle changes and medication.


American College of Cardiology


American Heart Association



Canadian Cardiovascular Society


Heart and Stroke Foundation of Canada



Acute coronary syndrome. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed/what.php. Updated October 2, 2012. Accessed October 30, 2012.

Achar SA, Kundu S, Norcross WA. Diagnosis of acute coronary syndrome. Am Fam Physician. 2005; 72:119-26.

Alexander KP, Newby LK, Cannon CP et al: Acute Coronary Care in the Elderly, Part I. Circ. 2007;115:2549-69

Anderson JL, Adams CD, et. al. ACC/AHA 2007 Guidelines for the Management of Patients With Unstable Angina/Non-ST-Elevation Myocardial Infarction. J Am Coll Cardiol. 2007;50;e1-e157.

Cohen M, Diez JE< Levine GN et al: Pharmacoiinvasive management of acute coronary syndrome: incorporating the 2007 ACC/AHA guidelines: the cATH(cardiac catherization and antithrombotic therapy in the hospital) Clinical Consensus Panel Report-III. J Invasive Cardiol. 2007:18:525-40.

Heart attack: Tips for recovering and staying well. Familydoctor.org website. Available at: http://familydoctor.org/online/famdocen/home/common/heartdisease/recovery/002.html. Updated January 2011. Accessed October 30, 2012.

Large GA. Contemporary management of acute coronary syndrome. Postgrad Med J. 2005; 81:217-222.

Swap CJ, Nagurney JT. Value and limitations of chest pain history in the evaluation of patients with suspected acute coronary syndromes. JAMA. 2005;294:2623-9.

Walker CW, Dewley CA, Fletcher SF:Aspirin combined with clopidogrel (Plavix) decreases cardiovascular events in patients with acute coronary syndrome. Am Fam Physician. 2007;7:1643-5.

What is angina? National Heart, Lung, and Blood Institute website. Available at: http://www.nhlbi.nih.gov/health/dci/Diseases/Angina/Angina_Treatments.html. Updated July 1, 2011. Accessed October 30, 2012.

7/7/2007 DynaMed's Systematic Literature Surveillance http://www.ebscohost.com/dynamed/what.php: O'Donoghue M, Boden WE, Braunwald E, et al. Early invasive vs conservative treatment strategies in women and men with unstable angina and non-ST-segment elevation myocardial infarction: a meta-analysis. JAMA. 2008;300:71-80.

Last reviewed September 2013 by Michael J. Fucci, DO

Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.

CreativeChangePowered by: Creative Change, Inc.