1.    Joint Commission Core Measures for Acute Myocardial Infarction

• PTCA (percutaneous transluminal coronary angioplasty) with 90 minutes.
• Fibrinolytic Therapy Received within 30 Minutes of Hospital Arrival.
• Aspirin given on arrival to facility and prescribed at discharge.
• ACE inhibitor (Lisinopril, Vasotec, and Captopril are examples) prescribed if EF (ejection fraction) <40%.
• Beta blocker (Metoprolol and Coreg are examples) prescribed at discharge.
• Statin (Zocor, Lipitor, and Crestor are examples) prescribed at discharge.
• Documentation of smoking cessation.

2.    When a patient presents with Chest Pain a complete history that includes risk factors for heart disease should be documented and taken into consideration when making a diagnosis

• Patient over the age of 45 have an eight times greater risk of Acute Myocardial Infarction.
• Cigarette smoking and secondhand exposure to smoke.
• Elevated cholesterol levels significantly increase the risk of Acute Myocardial Infarction.
• Diabetes Mellitus.
• Family history of ischemic heart disease in a fist-degree relative.
• Male gender

3.    Treatment and Diagnostic Testing Performed on Arrival to Facility

• A patient presenting with chest pain should have an ECG performed within 10 minutes of arrival to the facility.
• ECG is the main diagnostic tool for verifying the presence of Acute Myocardial Infarction.
• STEMI (ST elevation myocardial infarction) shows ST elevation of > 1 mm in two contiguous leads, >/= to 2 mm in men or >/= 1.5 mm in women in leads V2-V3, and >/= to 1 mm in other leads.
• NSTEMI (non-St elevated myocardial infarction) or Unstable Angina has the ECG showing new horizontal or down-sloping ST-segment depression >/= 5 mm in two contiguous leads and/or T wave inversion >/= 1 mm in two contiguous leads with prominent R wave or R/S (referring to r and s waves in the ECG) ratio.
• ECG assists in determining the coronary artery and part of the heart affected by the ischemia.
• The degree of deviation of the ST segment from baseline is proportional to the amount of injured heart muscle.
• All patient with diagnosed Acute Myocardial Infarction should have repeat ECG’s done 24 hours after the initial tracing and then again before discharge to monitor the progress of the infarction or success of reperfusion.[1]
• Cardiac biomarkers should be obtained. In the absence of ST-elevation on the EKG cardiac biomarkers help make the diagnosis of NSTEMI (non-ST elevation myocardial infarction).
• It should also be noted that Cardiac Troponin T levels increase rapidly from an abnormal baseline in patients with reinfarction.
• Measurements of Troponin levels should be done at time of presentation, and then every 3-6 hours up to the window of 24 hours.
• Troponin measurement at 72 hours can be used to estimate the size of the infarct, even if reperfusion was performed.
• It should be noted that Troponin levels can be elevated in patient with renal disease. Cardiac Troponin T levels appear to be elevated more often than Cardiac Troponin I levels in patient with renal insufficiency.[2]
• Aspirin should be given on arrival to the facility.
• Nitrates (nitroglycerin) is used for vasodilation thus increasing blood flow to the area and decreasing pain (should not be used in patients diagnosed with inferior wall acute myocardial infarctions due to possibility of right ventricular infarct which increases the patients preload/fluid needs).
• Morphine is used for treatment of pain in patients with STEMI.
• Beta-blockers are given to decrease the heart rate and increase the force of myocardial contraction thus decreasing the work load and oxygen demands of the heart.

4.    Reperfusion Therapy for STEMI (ST-elevated Myocardial Infarction)

• Reperfusion Therapy is the most important step in the management of patients with STEMI.
• Every 30 minute delay to treatment with Reperfusion Therapy increases the risk of mortality.
• Time to definitive treatment is within 30 minutes for fibrinolytic therapy and within 90 minutes for PCI (percutaneous coronary intervention). This time frame is very rigid in PCI – capable centers.  In patients that require transportation to a PCI – capable center PCI is the first option provided the time to treatment does not exceed 2 hours.
• Choice of Reperfusion Therapy relies on 3 factors:

1. Time from onset of symptoms as initiation of fibrinolytic therapy within 2 hours from the start of symptoms could terminate the STEMI thus decreasing the risk of death.
2. Percutaneous coronary intervention is the preferred technique in patients with a bleeding risk.
3. Availability of Percutaneous coronary intervention, including time needed for transfer, distance from the place of diagnosis to a percutaneous coronary intervention center, and availability of transportation.

• Coronary artery bypass surgery (CABG) is indicated in patient with STEMI and ongoing ischemia who are not candidates for either thrombolytic therapy or percutaneous coronary intervention. CABG is also considered a reasonable treatment in patients with left main stenosis of 50% or more and/or three-vessel disease.
• Patients that develop complications during percutaneous coronary intervention, the procedure was not successful, or are have ongoing ischemia should undergo emergency coronary artery bypass surgery.

 

5.    NSTEMI (Non-ST Elevations Myocardial Infarction)

• Fibrinolytic therapy is not beneficial for these patient, and may actually be harmful.
• Prompt antiplatelet and antithrombotic therapy should be promptly initiated with medications such as heparin, fondaparinux, and in patient that will be undergoing PCI (percutaneous coronary intervention) Angiomax.[3]
• Treatment for these patients may either be conservative using medical management therapies, or initiating early invasive therapy with angiography and revascularization with PCI or CABG (coronary artery bypass surgery).

6.    Unstable Angina

• Unstable Angina and non-ST elevation myocardial infarction differ primarily in whether the ischemia is severe enough to cause sufficient myocardial damage to have cardiac biomarkers become positive, thus indicating myocardial injury. Because elevation in cardiac biomarkers are often not detectable for up to 12 hours from onset of symptoms Unstable Angina and non-ST elevation myocardial infarction are frequently indistinguishable at the time of initial evaluation.
• The course of unstable angina can be highly variable and potentially life-threatening.
• Conservative management:
• Initiation of anticoagulant therapy
• Enoxaparin or unfractionated heparin
• Angiomax or fondaparinux
• Initiation of therapy with Clopidogrel.
• Consider the addition of Integrilin or tirofiban.
• Invasive Treatment
• Diagnostic Angiography.[4]

 

7.    Inferior Wall Acute Myocardial Infarction

• Suspect right ventricular wall infarct until ruled-out.
• Obtain right-sided EKG to assess for right ventricular wall infarct. ***
• Do not use nitrates for chest pain if a right ventricular wall infarct has not been ruled out.
• Patients with right ventricular wall infarcts have higher IV fluid needs to support their blood pressure.

 

8.    Monitoring for Reperfusion Complications

• Patients are not “cured” once they have undergone reperfusion therapy and the affected coronary arteries have been reopened.
• Return of blood flow can cause additional cardiac damage and complications referred to as reperfusion injury. This is more likely to occur when reperfusion therapy has been delayed.
• There are presently no effective therapies for reperfusion complications therefore post-reperfusion monitoring is essential.
• Monitoring should include monitoring of heart rate and rhythm, signs and symptoms of hemodynamic complications, systolic heart failure (low output failure), cardiogenic shock, right ventricular infarction, and pulmonary edema. An important part of the post reperfusion monitoring should be Continuous ST-segment Monitoring per ECG.

9.    ST-Segment Monitoring

• It is generally not practical or possible to perform continuous 12-Lead ECG St-segment monitoring. Therefore the area of the patient’s infarct should be taken into account when determining which leads are appropriate to monitor the patient in on the bedside monitor.
• Is the patient being monitored in Lead II (many nurses automatically monitor all of their patients in lead II)?
• Lead II does not assess adequately for ischemia.
• Leads to monitor for the different areas of infarct:
• Inferior Infarct (right coronary artery): Leads II, III, AVF.
• Lateral Wall Infarct (circumflex artery): Leads I, AVL, V, V6.
• Anterior Wall Infarct (left anterior descending branch of the left coronary artery): Leads V3, V4.
• Septal Infarct (intraventricular septum): Leads V1, V2.
• ST-Segment monitoring detects silent ischemia; the ECG will report the ischemia before the patient actually has symptoms clinically.
• The AACN (American Association of Critical-Care Nurses) published a Practice Alert regarding the need for ST-Segment Monitoring in post AMI patients in 2008.

10.   Checklist for Reviewing a Chest Pain Case

Check for adherence to Joint Commission Core Measures	Yes/No
Time of admission/Time of ECG	/
Complete history with risk factors documented	Yes/No
Aspirin given on arrival	Yes/No
STEMI, NSTEMI, or Unstable Angina documented
Time to initiation of Fibrinolytic Therapy when STEMI is present
Inferior Wall Infarct documented – was right sided ECG performed?	Yes/No
Close monitoring of heart rate and rhythm and hemodynamics done post reperfusion?	Yes/No
ST-Segment Monitoring done post reperfusion in appropriate lead?	Yes/No

 

[1] (Elsevier’s First Consult – Acute Myocardial Infarction)

[2] (Elsevier’s First Consult – Acute Myocardial Infarction)

[3] (Elsevier’s First Consult – Acute Myocardial Infarction)

[4] (Elsevier’s First Consult – Acute Myocardial Infarction)