Acute coronary syndrome
ACS is most commonly due to coronary artery atherosclerosis, the long-term result of a cascade of chronic inflammatory processes that lead to the development of plaques. The fibrous cap over the plaques may be unstable and can rupture, leading to thrombosis, which can partially or completely obstruct blood flow. Risk factors for atherosclerotic disease include hypertension, hyperlipidemia, diabetes, smoking, increased weight, increased age, male sex, renal insufficiency, sedentary lifestyle, Western diet, and family history of atherosclerotic disease. In the United States, ACS is most common in the sixth decade of life and has a male to female ratio of 3:2.
Less common causes of arterial obstruction that can result in ACS include embolic events, vasospasm, and coronary artery dissection. ACS may also occur as a result of diffuse myocardial ischemia and infarction in the setting of noncardiac disease such as severe anemia, hypoxemia, or sepsis. Rarely, acute rupture of the ventricular wall can occur in late-presenting cases of myocardial infarction.
ACS is a major cause of morbidity and mortality throughout the world; however, while overall cases have declined, cases of non-ST-elevation myocardial infarction (NSTEMI) have risen due to increasingly sensitive troponin assays.
ACS includes the following 3 diagnoses, which represent a spectrum of disease severity and are differentiated by ECG findings and serum cardiac enzyme (troponin) levels:
- ST-elevation myocardial infarction (STEMI) – New ST segment elevations on ECG and elevated cardiac enzyme levels.
- Non-ST-elevation myocardial infarction (NSTEMI) – Elevated cardiac enzyme levels without ST elevations. ST depressions and/or T-wave inversions may or may not be present on ECG.
- Unstable angina (UA) – Chest pain and/or other symptoms of ischemia that are new, worsening, or occurring at rest in the absence of abnormal cardiac enzyme levels. ST segment depression and T-wave inversion may or may not be present on ECG. This is distinguished from stable angina, in which chronic coronary artery disease causes chest discomfort that is provoked by exertion and resolves with rest in a predictable manner.
I20.0 – Unstable angina
I21.9 – Acute myocardial infarction, unspecified
394659003 – Acute coronary syndrome
- Microvascular angina
- Pericarditis – sharp pain, positional (improved with leaning forward), recent illness or myocardial infarction (or other risk factors), pericardial friction rub, diffuse ST elevations on ECG
- Aortic dissection – tearing chest pain, hypotension, tachycardia, CT
- Coronary vasospasm
- Coronary artery dissection
- Stress-induced cardiomyopathy
- Heart failure
- Mitral valve disease (eg, prolapse, regurgitation, or stenosis)
- Substance related (eg, cocaine-related cardiomyopathy)
- Expanding aortic aneurysm – positive risk factors (many are the same), ultrasound, or CT
- Pulmonary embolism – pleuritic chest pain, tachycardia, shortness of breath, syncope, evidence of right heart strain on ECG, CT angiogram
- Pneumonia – pleuritic chest pain, cough, fever
- Malignancy (see, eg, lung cancer)
- Acute chest syndrome
- Pulmonary hypertension
- Gastroesophageal reflux disease – burning pain, pain after eating large or spicy meals, pain on abdominal examination
- Peptic ulcer disease – positive risk factors
- Esophageal spasm
- Eosinophilic esophagitis
- Hiatal hernia
- Esophageal rupture / perforation
- Referred pain from abdominal viscera (eg, acute cholecystitis, pancreatitis) – positive risk factors, liver function tests, pancreatic enzyme levels
- Sickle cell crisis
- Costochondritis – sharp, localized, reproducible, history of traumatic injury
- Rheumatic diseases (eg, rheumatoid arthritis, fibromyalgia)
- Herpes zoster (shingles) – look for rash