Reviewed and updated by Valerie Dziados, MSN, CRNP, ANP-C, AGACNP-C: May 15, 2024

Coronary heart disease (CHD) is the leading cause of death in adults in the United States, accounting for every 1 in 5 deaths (CDC, 2023). In 2018 the American Heart Association reported 28.1 million people in the United States have CHD, and it is estimated that approximately every 40 seconds an American will suffer a myocardial infarction (Benjamin et al., 2018). Acute coronary syndrome (ACS) refers to a spectrum of three critical diagnoses associated with CHD: unstable angina (UA), non-ST elevated myocardial infarction (NSTEMI), and ST elevated myocardial infarction (STEMI) (Amsterdam et al., 2014). ACS occurs when there is severe reduction of perfusion to the myocardium, resulting in ischemia and/or infarction. Given its high prevalence and strong association with morbidity and mortality, ACS is a diagnosis that must not be missed.

Symptoms of ACS (Amsterdam et al., 2014)

The most widely recognized symptom of ACS is chest pain.  Chest pain, however, is a common symptom that can be linked to a multitude of etiologies listed in the table below. 

Causes of Chest Pain
Aortic dissection	Pulmonary causes (pleuritic pain, pneumonia, pneumothorax)
Expanding aortic aneurysm	Musculoskeletal causes (costochondritis, cervical radiculopathy)
Pericarditis/myocarditis	Psychiatric disorders
Pulmonary embolism	Sickle cell crisis
Gastrointestinal (GI) causes (gastroesophageal reflux disease [GERD], esophageal spasm, peptic ulcer disease)	Herpes zoster

 
 
In the setting of ACS, chest pain is frequently described as a pressure type sensation and can occur with rest or minimal exertion. Ischemic chest pain can radiate down the arms, to the neck, or jaw, and is commonly associated with diaphoresis, dyspnea, nausea, abdominal pain, or syncope. Importantly, new onset or increased exertional dyspnea is the most common anginal equivalent and is sometimes the only symptom.

There are several key patient characteristics or morbidities that increase suspicion that chest pain is caused by ACS:

• Older age
• Male sex
• Positive family history of coronary artery disease
• Presence of peripheral vascular disease, diabetes mellitus, renal insufficiency, prior myocardial infarction, or prior coronary revascularization

While chest pain is the most common symptom reported with ACS, nurses must also recognize the atypical symptoms of chest pain, which include epigastric pain, indigestion, stabbing or pleuritic pain, and increasing dyspnea in the absence of chest pain. An atypical presentation is most likely to occur in female patients, older patients (>75 years), and patients with diabetes mellitus, renal insufficiency, and/or dementia.

There are several features of chest pain that are not characteristic of ischemia, including:

• Pleuritic pain (sharp or knifelike pain provoked by respiration or cough)
• Primary or sole location of discomfort in the middle or lower abdomen
• Pain reproduced with movement or palpation of the chest wall or arms
• Brief episodes of pain lasting a few seconds or less
• Pain that is of maximal intensity at onset
• Pain that radiates into the lower extremities

Physical Exam (Amsterdam et al., 2014)

Physical examination can provide many important clues to help differentiate ACS from other diagnoses and it is important to exam the patient quickly, yet accurately. Many patients with ACS can present with a normal exam. Patients may present with signs of heart failure, but it is important to remember that heart failure signs can exist without ACS, and thus heart failure symptoms are nonspecific. Additional signs of ACS can include the presence of an S4 heart sound, a paradoxical splitting of S2, or a new murmur of mitral regurgitation due to papillary muscle dysfunction. The following exam findings should raise concern for other diseases as mentioned below:

• Pain on palpation – think musculoskeletal disease or inflammation
• Pulsatile abdominal mass – think abdominal aortic aneurysm
• Back pain with unequal palpated pulse volume, a difference of greater than or equal to 15 mm Hg in systolic blood pressure between both arms, or a murmur of aortic regurgitation – think aortic dissection
• Pericardial friction rub – think acute pericarditis
• Pulsus paradoxus – think cardiac tamponade
• Pleural friction rub – think pneumonitis or pleuritis

Electrocardiogram (Amsterdam et al., 2014; Reeder, Awtry, & Mahler, 2018)

ACC/AHA guidelines suggest the 12-lead ECG (electrocardiogram) is pivotal in the decision pathway for the evaluation and management of patients presenting with symptoms suggestive of ACS and recommend an ECG should be performed and interpreted within 10 minutes of arrival to the emergency department/office. The initial ECG is often NOT diagnostic in patients with ACS, thus a normal ECG does not exclude ACS. The ECG should be repeated at 15 to 30-minute intervals if the initial study is not diagnostic, especially if  the patient remains symptomatic and/or there is a high clinical suspicion for ACS persists. Keep in mind that left ventricular hypertrophy, bundle-branch blocks with repolarization abnormalities, and ventricular pacing may mask signs of ischemia/injury. ECG changes consistent with ischemia or injury with ACS may include ST depression (especially horizontal or down-sloping), transient ST-elevation, or new T-wave inversion. In the setting of a STEMI, nurses can expect to see new ST elevation at the J point in two anatomically contiguous leads; however, in the early hours of infarction, peaked, hyperacute T waves may be the only abnormality. In the setting of UA/NSTEMI, new horizontal or down-sloping ST depression in two anatomically contiguous leads and/or T wave inversion in two anatomically contiguous leads may be observed.

Cardiac Biomarkers (Amsterdam et al, 2014; Reeder, Awtry, & Mahler, 2024)

Serial serum biomarkers, namely troponin T and I are sensitive and specific to acute myocardial damage and are essential for confirming the diagnosis of infarction. High sensitivity troponin is the preferred test. They should be obtained as soon as possible in any patient at significant risk of ACS at presentation and repeated in three to six hours. Additional troponin levels beyond six hours may be considered when there is an intermediate to high suspicion of ACS or when dynamic EGC changes are noted. By definition, patients with UA will have normal troponin levels and patients with STEMI or NSTEMI will have elevated troponin levels.  Troponins may be normal at the onset of an acute cardiac event and may not be elevated until 2 to 4 hours after symptom onset in STEMI/NSTEM. Elevated troponin can be used to evaluate infarct size, to diagnose reinfarction, and for prognosis. 

ACS is a common, life threatening condition that nurses frequently encounter. Timely recognition of ACS is necessary for immediate management, which is crucial to reduce the risk of mortality and further cardiac events. Nurses have a crucial role in early recognition of ACS, as well as administering treatment, and helping patients to understand their condition and care.

 

References: 
Amsterdam, E.A., Wenger, N.K., Brindis, R. G., Casey, D.E., Ganatis, T. G., & Holmes, D.R. (2014). 2014 AHA/ACC Guideline for the Management of Patients with Non–ST-Elevation Acute Coronary Syndromes A Report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines. Circulation 130, e344-e426. doi: 10.1161/CIR.0000000000000134

Benjamin, E.J., Virani, S.S., Callaway, C.W., Chamberlain, A.M., Chang, A.R., Cheng, S.,...Munter, P. (2018). Heart Disease and Stroke Statistics—2018 Update: A Report From the American Heart Association. Circulation, 137, e67-e492. doi: 10.1161/CIR.0000000000000558

Centers for Disease Control and Prevention. (2023). Heart Disease Fact Sheet. Retrieved from https://www.cdc.gov/dhdsp/data_statistics/fact_sheets/fs_heart_disease.htm

Reeder, G. S., Awtry, E., & Mahler, S. A. (2024). Initial evaluation and management of suspected acute coronary syndrome (myocardial infarction, unstable angina) in the emergency department, UpToDate. Retrieved May 15, 2024, from https://www.uptodate.com/contents/initial-evaluation-and-management-of-suspected-acute-coronary-syndrome-myocardial-infarction-unstable-angina-in-the-emergency-department