ICD-10 Diagnosis Code I21.21

STEMI involving left circumflex coronary artery

Diagnosis Code I21.21

ICD-10: I21.21
Short Description: STEMI involving left circumflex coronary artery
Long Description: ST elevation (STEMI) myocardial infarction involving left circumflex coronary artery
This is the 2017 version of the ICD-10-CM diagnosis code I21.21


Code Classification
  • Diseases of the circulatory system (I00–I99)
    • Ischemic heart diseases (I20-I25)
      • STEMI & NSTEMI mocard infrc (I21)

Information for Medical Professionals

Diagnostic Related Groups
The diagnosis code I21.21 is grouped in the following Diagnostic Related Group(s) (MS-DRG v33.0)

  • CARDIAC DEFIBRILLATOR IMPLANT WITH CARDIAC CATHETERIZATION WITH AMI/HF/SHOCK WITH MCC 222
  • CARDIAC DEFIBRILLATOR IMPLANT WITH CARDIAC CATHETERIZATION WITH AMI/HF/SHOCK WITHOUT MCC 223
  • CARDIAC DEFIBRILLATOR IMPLANT WITH CARDIAC CATHETERIZATION WITHOUT AMI/HF/SHOCK WITH MCC 224
  • CARDIAC DEFIBRILLATOR IMPLANT WITH CARDIAC CATHETERIZATION WITHOUT AMI/HF/SHOCK WITHOUT MCC 225
  • CARDIAC DEFIBRILLATOR IMPLANT WITHOUT CARDIAC CATHETERATION WITH MCC 226
  • CARDIAC DEFIBRILLATOR IMPLANT WITHOUT CARDIAC CATHETERIZATION WITHOUT MCC 227

Convert to ICD-9 Additional informationCallout TooltipGeneral Equivalence Map
The ICD-10 and ICD-9 GEMs are used to facilitate linking between the diagnosis codes in ICD-9-CM and the new ICD-10-CM code set. The GEMs are the raw material from which providers, health information vendors and payers can derive specific applied mappings to meet their needs.

Index of Diseases and Injuries
References found for the code I21.21 in the Index of Diseases and Injuries:


Information for Patients


Heart Attack

Also called: MI, Myocardial infarction

Each year over a million people in the U.S. have a heart attack. About half of them die. Many people have permanent heart damage or die because they don't get help immediately. It's important to know the symptoms of a heart attack and call 9-1-1 if someone is having them. Those symptoms include

  • Chest discomfort - pressure, squeezing, or pain
  • Shortness of breath
  • Discomfort in the upper body - arms, shoulder, neck, back
  • Nausea, vomiting, dizziness, lightheadedness, sweating

These symptoms can sometimes be different in women.

What exactly is a heart attack? Most heart attacks happen when a clot in the coronary artery blocks the supply of blood and oxygen to the heart. Often this leads to an irregular heartbeat - called an arrhythmia - that causes a severe decrease in the pumping function of the heart. A blockage that is not treated within a few hours causes the affected heart muscle to die.

NIH: National Heart, Lung, and Blood Institute

  • Being active after your heart attack
  • Cardiac catheterization
  • Cardiac catheterization - discharge
  • Heart attack
  • Heart attack - discharge
  • Learn What a Heart Attack Feels Like--It Could Save Your Life - NIH - Easy-to-Read (National Heart, Lung, and Blood Institute)
  • Talk With Your Health Care Provider About Taking Aspirin to Prevent Heart Attack (Agency for Healthcare Research and Quality)
  • Troponin test


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