Myocardial Infarction Nursing Guide

Myocardial Infarction Definition: 

Myocardial infarction, also referred to as acute coronary syndrome, happens when the blood flow to the heart muscle is interrupted (DynaMed, 2018). The decreased blood flow causes ischemia and necrosis of the myocardium. 

There are biomarkers released into the blood at the time of cardiac muscle necrosis. The level these biomarkers rise indicates the extent of the myocardial damage. The biomarkers that elevate during a myocardial infarction are: 

• Troponin I or Troponin T (proteins typically found in skeletal or heart muscle fibers) 
• Creatinine kinase or CK (enzyme secreted when muscle is damaged) 

There are two classifications of myocardial infarction: 

• ST-elevation myocardial infarction (STEMI): ST-segment elevation on electrocardiogram (ECG) with a release of biomarkers for myocardial necrosis. The cause of this type of myocardial infarction is a plaque rupture in the coronary arteries leading to total occlusion of the vessel by a thrombus. 
• Non-ST-elevation myocardial infarction (NSTEMI): Biomarkers will be elevated without elevation of the ST-segment. There may be ST-segment depression, inverted T-wave, or both revealed on the ECG. 

The most common cause of myocardial infarction is a rupture of atherosclerotic plaque in the coronary arteries (DynaMed, 2018). These arteries supply blood flow directly to the myocardium. Other causes of myocardial infarction include: 

• Coronary vasospasm 
• Atherosclerotic obstruction without clot or vasospasm 
• Inflammation or infections 
• Thrombus formation causing coronary artery occlusion 

Risk factors for myocardial infarction are: 

• Coronary artery disease (CAD) 
• Tobacco use 
• Dyslipidemia 
• Hypertension 
• Diabetes mellitus 
• Family history 

Men are affected by myocardial infarction more than women at a rate of 3:2 (DynaMed, 2018). Approximately 30% of myocardial infarctions are STEMI and 70% are NSTEMI. There are more than 780,000 Americans who have a myocardial infarction each year. Globally, cardiovascular disease is the number one cause of death (Sanam et al., 2019). 

Acute Myocardial Infarction ICD-10 Code (unspecified): I21.9

Myocardial Infarction Diagnosis 

The European Society of Cardiology released guidelines for managing acute coronary syndromes in individuals with NSTEMI (DynaMed, 2021). They recommend that diagnosis should be made considering a combination of: 

• Clinical history 
• Symptoms 
• Vital signs 
• ECG results 
• Laboratory test results for CK and troponin levels 

Individuals with symptoms such as chest pressure in the retrosternal area occurring at rest or with minimal exertion and dyspnea should be suspect for myocardial infarction (DynaMed, 2018). A myocardial infarction must be confirmed with an ECG and biomarker studies. There may be T-wave inversion, ST-segment depression, and elevated troponin levels if there is no ST-segment elevation. NSTEMI can appear clinically similar to a condition known as unstable angina, but the rise of cardiac biomarkers will make the distinction. 

Management & Treatment of Myocardial Infarction

Treatment for suspected myocardial infarction should start early with care in a hospital. Initial treatment begins with medications that reduce myocardial ischemia such as antiplatelet or anticoagulant therapy. Medical therapy should include (DynaMed, 2018): 

• Aspirin, non-enteric coated chewable (Bayer Chewable®), 162 mg to 325 mg as soon as possible. 
• Nitroglycerin (Nitrostat®), 0.3 to 4.0 mg sublingually every 5 minutes up to a maximum of three doses. 
• Morphine IV (Duramorph®), 4 to 8 mg as needed to relieve pain, anxiety, or pulmonary edema. 
• Maintain complete bed rest until the individual is stable. 
• Clear liquid diet if invasive treatment is ordered. 
• Administer low flow oxygen (1 to 3 liters per minute) via nasal cannula. The rate may be increased if oxygen levels drop below 90%. 
• Beta Blockers such as diltiazem (diltiazem (Cardizem®) or metoprolol (Toprol®, Lopressor®) should be started in the first 24 hours of suspected myocardial infarction. 
• For individuals with hypertension, low left ventricular function, or chronic kidney disease, an ACE-Inhibitor should be initiated such as enalapril (Vasotec®) or lisinopril (Zestril®). 
• IV nitroglycerin should be started if ischemia persists or if the individual is in heart failure. 
• Avoid the use of nonsteroidal anti-inflammatory drugs (NSAIDs) except for aspirin. NSAIDS can lead to increased ischemia. 

If an invasive procedure is ordered, such as percutaneous coronary intervention (PCI), it is recommended that PCI is performed for STEMI within 12 hours of symptom onset but preferably within 2 hours. If PCI cannot be completed within 2 hours, then fibrinolytic therapy should be initiated. 

Coronary artery bypass graft (CABG) is recommended for STEMI if the individual cannot have a PCI related to recurrent ischemia, cardiogenic shock, or severe heart failure. 

Nursing Considerations 

Use the nursing process to develop a plan of care for individuals. The nursing assessment (with common findings listed), diagnoses, interventions, expected outcomes, and education for myocardial infarction are listed below. 

Assessment 

Assess signs and symptoms, such as: 

• Medical history, including previous or family history of coronary artery disease or a recent illness 
• Chest pain, location, radiation, strength, onset, duration, and precipitation factors 
• Complaints of indigestion or heartburn 
• Vital signs, including pulse oximetry 
• Shortness of breath dyspnea, tachypnea 
• Crackles upon lung auscultation 
• Mental status, confusion, or restlessness 
• Nausea, vomiting, or hiccups 
• Pain in abdomen, back, or shoulders 
• Numbness or tingling, especially in the arms 
• Pain radiating to the neck or jaw 
• Cardiac arrhythmias during the acute phase 
• Contraindications to anticoagulant therapy such as: 
  • Bleeding abnormalities 
  • Surgery 
  • Stroke 
  • Trauma 
  • Recent biopsy 
  • Malignant hypertension 
  • Advanced retinopathy 
• Support system and those who can act as a caregiver if needed during recovery 
• Communication level and coping mechanisms. 
• Signs of heart failure such as crackles in the lungs, jugular vein distension, hepatojugular reflux, abnormal heart sounds or murmurs, and edema 

Nursing Diagnosis/Risk For 

• Anxiety related to change in health status as evidenced by (Phelps, 2021a): 
  • Diagnosis of myocardial infarction 
  • Fear of dying 
• Risk for decreased cardiac output related to myocardial infarction as evidence by (Phelps, 2021b): 
  • Potential for altered afterload 
  • Potential for altered myocardial contractility 
  • Potential for altered preload 
  • Potential for altered stroke volume 
• Risk for decreased cardiac tissue perfusion as evidenced by (Phelps, 2021c): 
  • Acute myocardial infarction 
  • Potential for cardiac arrhythmias 
  • Coronary artery spasm 
  • Coronary artery blockage 

Interventions 

• Administer IV and PO medications as ordered. 
• Provide emotional support for the individual and the family by allowing them to express their concerns. 
• Teach the individual relaxation techniques such as box breathing, music therapy, and aromatherapy. 
• Insert and maintain a patent IV site. 
• Monitor for hemodynamic changes. These changes may indicate decreased altered cardiac perfusion, such as blood pressure, heart rate and rhythm, respiratory rate, and oxygen saturation. 
• Monitor vital signs, including orthostatic vital signs, at routine intervals. 
• Provide continuous cardiac monitoring. 
• Monitor intake and output. 
• Administer oxygen therapy as ordered. 
• Provide the individual with education regarding modifiable risk factors for myocardial infarction. 
• Encourage individuals and their families to ask questions to help reduce anxiety. 
• Assist with preparation and recovery of diagnostic testing and invasive procedures. 
• Provide the individual with education regarding testing and invasive procedures, including a recovery plan. 

Expected Outcomes 

• Remains hemodynamically stable 
• Remains free from symptoms of decreased cardiac tissue perfusion such as chest pain, shortness of breath, tachycardia, or hypotension 
• Identifies reportable symptoms of possible decreased cardiac perfusion 
• Verbalizes modifiable risk factors for myocardial infarction 
• Demonstrates effective coping with the current medical situation 
• Verbalizes fears and anxieties 

Patient/Caregiver Education 

• Condition, treatment, and expected outcomes 
• Modifiable risk factors for myocardial infarction 
• Techniques to reduce stress and anxiety 
• Prescribed medication and diet 
• Procedures to be performed and aftercare 
• Recommended follow-up with cardiologist/healthcare provider 
• Notify healthcare providers or seek immediate medical care for: 
  • Chest pain or tightness 
  • Shortness of breath 
  • Cold sweat 
  • Pain in arms, back, neck, jaw 
  • Sudden nausea or vomiting 
  • Sudden unexplained fatigue 
  • Light-headedness or dizziness

Content Release Date 

4/1/2022

Content Expiration

12/31/2026

Course Contributor 

The content for this course was revised by Kathleen Koopmann, RN, BSN, PCCN. Kathleen earned her Associate Degree in nursing in 1987 at Mid-Michigan Community College and her Bachelor of Science in nursing in 2018 from Western Governor’s University. She has training from the North Carolina Statewide Program for Infection Control and Epidemiology through NCDHHS and the University of North Carolina. Kathleen has worked in long-term care, outpatient care, acute care, and nursing education. She has hospital experience in Med-Surg, OR/PACU, Critical Care, Telemetry, and outpatient experience in Occupational Health. Kathleen has experience as a clinical instructor for the LPN program at Susquehanna County Career and Technical Center in Pennsylvania. Most recently, she worked in long-term care as a Staff Development Coordinator and Infection Control Practitioner. 

Resources 

• American Heart Association https://www.heart.org 

References 

• DynaMed. (2018). Acute coronary syndromes. https://www.dynamed.com/condition/acute- coronary-syndromes 
• Phelps, L. L., (2021a) Sparks and Taylor’s nursing diagnosis pocket guide (4th ed., pp. 605- 606). Wolters Kluwer. 
• Phelps, L. L., (2021b) Sparks and Taylor’s nursing diagnosis pocket guide (4th ed., pp. 74-76). Wolters Kluwer. 
• Phelps, L. L., (2021c) Sparks and Taylor’s nursing diagnosis pocket guide (4th ed., pp. 23-25). Wolters Kluwer. 
• Safi, S., Sethi, N. J., Nielsen, E. E., Feinberg, J., Jakobsen, J. C., & Gluud, C. (2019). Beta- blockers for suspected or diagnosed acute myocardial infarction. The Cochrane database of systematic reviews, 12(12), CD012484. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6915833/