LISA HAUK, AFP Senior Associate Editor
Am Fam Physician. 2015;92(2):151-153
• Cardiac troponin levels should be measured on arrival and again three to six hours after the patient's symptoms began.
• ECG should be performed every 15 to 30 minutes within the first hour in patients with ACS if the original ECG did not confirm the diagnosis.
• Oral beta blockers should be started within 24 hours of presentation, if there are no contraindications.
• Treatment with ACE inhibitors is recommended in persons with a left ventricular ejection fraction less than 0.40, hypertension, diabetes mellitus, or stable chronic kidney disease.
• Chewable aspirin without an enteric coating, at a dose of 162 to 325 mg, should be administered as soon as possible.
• Dual antiplatelet therapy with ticagrelor or clopidogrel in combination with aspirin should be given for up to one year in the invasive and ischemia-guided treatment approaches.
From the AFP Editors
Acute coronary syndrome (ACS), a term that encompasses a range of conditions, is caused when blood flow to the heart is suddenly reduced. The American College of Cardiology (ACC), with the American Heart Association (AHA), has provided recommendations for managing non–ST elevation ACS.
To determine whether or not a patient should be admitted to the hospital, and to guide treatment decisions, persons with symptoms of ACS should be evaluated based on their probability of having ACS and adverse outcomes. Those with high-risk symptoms (e.g., persistent chest pain, severe dyspnea, syncope) should be transferred to the emergency department right away, and those with less severe symptoms at presentation can be referred to the emergency department, a chest pain unit, or another office that can appropriately assess the patient's symptoms.
On presentation to the emergency department, persons with symptoms consistent with ACS should be evaluated with 12-lead electrocardiography (ECG) within 10 minutes to determine if there are any ischemic changes. Additionally, cardiac troponin levels (I or T) should be measured on arrival, after which they should be measured again three to six hours after the patient's symptoms began. If it is not known when symptoms started, time of patient presentation can be used. In patients whose initial troponin levels, as well as levels obtained three to six hours after symptom onset, are normal, but who have ECG results that indicate immediate or high risk, additional measurements should be obtained. When confirming a diagnosis of ACS, creatine kinase-myocardial isoenzyme and myoglobin measurements are not useful.
If the original ECG did not confirm a diagnosis, but ACS is still suspected, ECG should be performed every 15 to 30 minutes within the first hour. Additionally, in those at intermediate or high risk whose original ECG does not confirm ACS, additional readings can be obtained in leads V7 to V9; constant monitoring with 12-lead ECG may also be an option.
B-type natriuretic peptide or N-terminal pro-B-type natriuretic peptide testing can help determine a patient's risk of ACS, and may be useful for determining prognosis. Prognosis in persons with non–ST elevation ACS should be determined using risk scores, and treatment may be helped with the use of risk-stratification models. Troponin levels, depending on the elevation, can help with determining prognosis. In persons with myocardial infarction, obtaining troponin levels again three or four days after presentation may be beneficial for estimating size of the infarct and dynamics of necrosis.
Monitoring in a chest pain or telemetry unit is an option for persons with symptoms suggestive of ACS, but who do not appear to have myocardial ischemia; this should be done with serial ECG and measurement of troponin levels every three to six hours. Before patients with normal findings on serial ECG and normal troponin levels are discharged from the emergency department, or in the 72 hours following, treadmill ECG, stress myocardial perfusion imaging, and stress echocardiography are options. For those with no history of coronary artery disease, coronary computed tomography angiography or resting myocardial perfusion imaging performed with a technetium-99m radiopharmaceutical are reasonable initial options to evaluate coronary artery anatomy and exclude myocardial ischemia, respectively. When these tests are performed as an initial evaluation, serial ECG and troponin measurements are not necessary. Persons at low risk of ACS who are referred for testing in an outpatient setting can receive aspirin daily, and short-acting nitroglycerin and other medication as needed; however, physicians should educate them about activity levels and schedule a follow-up appointment.