Acute Coronary Syndromes

hypertension, as well as a positive family history of MI. Drug use, particularly cocaine use, can contribute to vasospastic heart disease.

In your examination, look for vital signs, body mass index, cyanosis, diaphoresis, neck vein distention, adenopathy, lung sounds, heart sounds, carotid bruits, herpes zoster lesions, abdominal and chest tenderness, leg swelling and edema. You should be concerned if you see abnormalities of the vital signs, hypoperfusion, dyspnea, hypoxemia, new heart murmurs, pulsus paradoxus, or asymmetry of the lung sounds or pulse.

The exacerbation and relief of the pain can help with the diagnosis. Pain with exercise that relieves itself with rest can be anginal pain. Nocturnal pain can be vasospasm, acute coronary syndrome, or heart failure. Pain when lying down can be GERD-related pain. Tenderness by itself does not rule out coronary causes because up to 15 percent of cardiac patients have chest wall tenderness. Nitroglycerin can relieve MI pain, biliary pain, and esophageal pain.

All patients should have pulse oximetry, chest x-ray, and ECG testing. With possible coronary pain, serial ECGs are necessary. Troponin levels that are low rule out cardiac causes in most cases, although the level will not rise immediately after an occlusion. A normal pulse oximetry does not rule out a pulmonary embolism, if it is small. D-dimer testing, if normal, rules out a pulmonary embolism but, if high, does not prove one.

ACUTE CORONARY SYNDROMES

All acute coronary syndromes come from a sudden obstructive event of a coronary artery. Depending on the degree of obstruction and its location, the diagnosis can be unstable angina, non-ST-segment elevation MI or NSTEMI, or ST-segment elevation MI or STEMI. Sudden cardiac death is another acute coronary syndrome. All patients, except in sudden death, will describe chest discomfort plus the possibility of nausea, vomiting, dyspnea, and diaphoresis.

Unstable angina involves prolonged coronary pain at rest or increasing severity of previously stable angina. The patient may have transient ECG changes of any type but

will not have an elevation of the troponin or CK-MB level. Because this can easily lead to an MI, it should be considered serious.

NSTEMI is a subendocardial myocardial infarction with positive enzymes but ECG changes revealing ST-segment depression and/or T wave inversion. STEMI will have a transmural MI with ST-segment elevation, new left bundle branch block and elevation of troponin and CK-MB elevation. Figure 1 shows the ECG changes in a STEMI:

Figure 1.

The majority of cases of acute coronary syndrome is an acute thrombus in a coronary artery that had prior atherosclerosis. Atheromas come from instability or inflammation of a stable plaque that activates platelets, leading to a blood clot in the vessel. Less common causes include embolism to a coronary artery, arterial vasospasm, and coronary artery dissection. Cocaine is the most common cause of vasospasm to the