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Acute coronary syndrome is a group of symptoms that together are characteristic of the heart not receiving enough blood.
Acute coronary syndrome (ACS) is a group of symptoms that together are characteristic of the heart not receiving enough blood. If the arteries to the heart become narrowed or blocked, the heart receives insuffi- cient oxygen, thereby causing angina and/or myocardial infarction (MI), the 2 conditions that fall under the heading of ACS. MI means that the artery or arteries have become blocked and the heart has been damaged. Without oxygen, part of the heart will die. ACS is an absolute medical emergency.
Unstable angina occurs when blood flow to the heart slows suddenly. This can be due to small blood clots forming in the arteries, plaque buildup, or hardening of the arteries. Unstable angina typically does not damage the heart and occurs at rest. Symptoms may not improve with rest or medication. Unstable angina is a strong warning that an MI can occur soon.
PREVALENCE
Heart disease is the leading cause of death in the United States, and the number of affected individuals continues to increase.1 According to the CDC, 27.6 million American adults have been given a diagnosis of heart disease.2 Men are more likely than women to have it. The incidence of heart disease increases with age, and certain ethnic groups are at high risk, including native Hawaiian or other Pacific Islanders, American Indian/white, Alaskan native/white, and black or African American/white. Additionally, the rate of heart disease varies greatly across the United States, with Mississippi having the highest rate and Colorado having the lowest rate.2
RISK FACTORS
Nonmodifiable risks include age, gender, genetics, race, and ethnicity. Modifiable risk factors include lifestyle factors and medical conditions. Lifestyle factors, such as diet, tobacco use, sedentary lifestyle, and poor oral hygiene, can increase the risk of ACS. Medical conditions can, as well, including hypercholesterolemia, hypertriglyceridemia, a low high-density lipoprotein level, abdominal obesity, diabetes with or without insulin resistance, testosterone deficiency, and hypertension.3 Finally, nonsteroidal anti-inflammatory drugs (NSAIDs), excluding aspirin, carry heart risks. Patients who have had an MI should not take NSAIDs unless approved by their doctor.4
PROGNOSIS
Patients can recover fully from an MI, it may devolve into a chronic debilitating condition, or it may be rapidly fatal. It all depends on the severity of the MI, the amount of damage to the heart muscle, and preventive measures taken after the MI. Patients with a previous MI are at higher risk for another MI, heart failure, arrhythmias, heart valve damage, and stroke.4 Women are more likely than men to die of an MI, and this gender difference is higher in younger patients. An MI is more serious in the elderly and in patients with diabetes, on long-term dialysis, and with heart disease.4 The severity of the MI increases when the patient experiences other conditions during the MI. Arrhythmias, cardiogenic shock, atrioventric- ular block (also known as heart block), and heart failure can all occur in conjunction with an MI, and all negatively affect the prognosis.
SYMPTOMS
Signs and symptoms of ACS include angina. Anyone experiencing angina should seek immediate medical attention and should never drive themselves to the hospital. Angina feels like pressure, squeezing, fullness, or pain in the center of the chest. For patients with stable angina, the discomfort will last for a few minutes, and then diminish. With unstable angina or MI, the discomfort usually lasts for more than a few minutes and will come back.4 Patients having a heart attack may also feel discomfort in the arms, neck, back, jaw, or stomach. Shortness of breath may take place with or without angina. Symptoms of an MI also include nausea, vomiting, breaking out in a cold sweat, and lightheadedness or fainting.4
DIAGNOSIS
Diagnosis includes patient or caregiver reporting of symptoms, duration, and medical history, as well as a detailed physical exam and an electrocardiogram (ECG) reading. An ECG can determine if heart problems are causing chest pain and, if so, the severity.5,6 Blood will be tested for certain biologic markers indicative of an MI, including troponins and creatine kinase myocardial bands. The primary care provider may also order an echocardiogram and perfusion scintigraphy to help rule out an MI.5,6 Radionuclide imaging, also called a thallium stress test, is noninvasive and can determine if an MI has occurred, as well as the location and extent of cardiac muscle damage.4 Angiography is an invasive test for patients showing strong evidence of severe obstruction.4
TREATMENT
Immediate treatment of ACS includes the use of oxygen, aspirin, and pain relievers. If the oxygen saturation rate is below 94% or the patient seems short of breath, oxygen should be administered.7 Adult-strength aspirin should be administered. Medications for relieving symptoms include nitroglycerin and morphine. Nitroglycerin increases blood flow to the heart by decreasing blood pressure and opening the blood vessels around the heart.4,5,7 Morphine will reduce anxiety, relieve pain, and open blood vessels and is the drug of choice for an MI. Caution should be used when administering morphine to patients with unstable angina.4,5,7 After symptoms have been relieved, the arteries must be opened to decrease permanent damage to the heart muscles. Typical medical and surgical solutions include angioplasty, thrombolytics, and coronary artery bypass graft (CABG). Throughout the ACS process, several drug classes can be used to decrease ischemia and improve the prognosis. Online Table 14,5 shows drug classes, actions, and results.
Table 1. Medications Used in Acute Coronary Syndrome
Drug Class
Action
Result
Antiplatelet drugs
Inhibit blood platelets from sticking together and forming clots
Fewer clots to block arteries
Anticoagulant drugs
Thin the blood to help keep clots from forming
Fewer clots to block arteries
Βeta-blockers
Slow heart rate and lower pressure in the arteries
Reduce oxygen demand by the heart and may help prevent arrhythmias
Calcium channel blockers
Inhibit contraction of myocardium and vascular smooth muscle
Reduce myocardial oxygen demand, cause coronary vasodilation, and improve myocardial blood flow
Angiotensin-converting enzyme inhibitors
May provide benefit for patients with unstable angina not responsive to nitrates and beta-blockers or who are unable to take beta-blockers
Improve mortality
Statins
Lower low-density lipoprotein levels in blood
Improve prognosis and mortality
Furosemide
For patients in heart failure
Improve prognosis and mortality
Antiarrhythmic drugs
Prevent arrhythmias
Maintain the heart’s pumping action necessary to keep up circulation
PREVENTION
The risk of a second MI can be reduced by following secondary preventive measures. In addition to the measures listed in Online Table 2, lifestyle choices such as not smoking and improving dietary factors are equally important.
Table 2. Preventive Measures for Acute Coronary Syndrome
Action
Measure to Aim For
Blood pressure
<130/80 mm Hg
Cholesterol
Low-density lipoprotein l <100 mg/dL
Triglycerides <200 mg/dL
Non—high-density lipoprotein <130 mg/dL
Exercise
30-60 minutes 5-7 days per week
Body mass index
18.5-24.8
Waist circumference
Men: <40 inches
Women: <35 inches
Medications
Follow primary care provider’s instructions
Adapted from reference 4.
REHABILITATION
Physical rehabilitation is imperative after an MI. Leg exercises may start by sitting up the first day and by walking as early as the second or third day. After 8 to 12 weeks, patients often benefit from supervised exercise programs. Emotional rehabilitation includes regular screening for depression in all patients who have had an MI, as study results suggest that depression is a major risk factor for increased mortality. One reason for this is that depressed patients are less likely to comply with their medication regimen.
Dr. Kenny earned her doctoral degree from the University of Colorado Health Sciences Center. She has 20+ years’ experience as a community pharmacist and works as a clinical medical writer based out of Colorado Springs, Colorado. Dr. Kenny is also the Colorado Education Director for the Rocky Mountain Chapter of the American Medical Writer’s Association and a regular contributor to Pharmacy Times®.
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