Diagnosing Acute Coronary Syndrome
What is Acute Coronary Syndrome?
The term Acute Coronary Syndrome (ACS) refers to any group of clinical symptoms indicative of acute myocardial ischemia, and covers both acute myocardial infarction (heart attack) and unstable angina (Figure 1). The precipitating event is the rupture of an unstable atherosclerotic plaque with subsequent formation of a thrombus, leading to partial (unstable angina) or complete (myocardial infarction) occlusion of coronary arteries (Figure 2).
These life-threatening disorders are a major cause of emergency room attendance and hospitalization in industrialized countries. In the United States alone, approximately 0.9 million people are discharged from hospital with ACS every year.
[Thom T et al. Heart disease and stroke statistics - 2006 update: a report from the American Heart Association Statistics Committee and Stroke Statistics Committee. Circulation 2006; 113: e85-e151.]
Figure 1 ACS disease continuum: from low risk (stable angina) to moderate (unstable angina) and high risk (myocardial infarction)
The most common symptom of ACS is intense pain felt in the middle of the chest and which may spread to the arms and the jaw. Chest pain may be accompanied by a drop in blood pressure, sweating, nausea, shortness of breath, etc.
The major risk factors for ACS include diabetes, smoking, family history, obesity and high cholesterol. Among all patients younger than 70 years, the incidence of ACS is higher in males. The incidence of ACS rises progressively with increasing age.
Initial assessment includes case history, physical examination, an electrocardiogram (ECG), and frequently, serum cardiac marker determination.
If the ECG confirms changes suggestive of acute myocardial infarction, thrombolysis may be administered or primary coronary angioplasty may be performed. If the ECG does not show typical changes, the patient may have suffered unstable angina, which is empirically treated with anti-thrombotic therapy.
Figure 2 Cross-section of unstable plaque
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