Acute Coronary Syndrome: Not 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 1^4,5 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®.

References:

• Kochanek KD, Murphy SL, Xu J, Tejada-Vera B. National vital statistics reports: deaths: final data for 2014. CDC website. cdc.gov/nchs/data/nvsr/nvsr65/nvsr65_04.pdf. Accessed August 5, 2016.
• Summary health statistics: national health interview survey, 2014. CDC website. ftp.cdc.gov/pub/Health_Statistics/NCHS/NHIS/SHS/2014_SHS_Table_A-1.pdf. Accessed August 5, 2016,
• Huma S, Tariq R, Amin F, et al. Modifiable and non-modifiable predisposing risk factors of myocardial infarction: a review. J Pharm Sci & Res. 2012;4(1):1649-1653.
• Heart attack and acute coronary syndrome. University of Maryland Medical Center website. umm.edu/health/medical/reports/articles/heart-attack-and-acute-coronary-syndrome. Accessed August 5, 2016.
• Kumar A, Cannon CP. Acute coronary syndromes: diagnosis and management, part 1. Mayo Clin Proc. 2009;84(10):917-938. doi: 10.1016/S0025-6196(11)60509-0.
• Achar SA, Kundu S, Norcross WA. Diagnosis of acute coronary syndrome. Am Fam Physician. 2005;72(1):119-126.
• Acute coronary syndromes algorithm. Advanced Cardiovascular Life Support Training Center website. acls.net/acute-coronary-syndromes-algorithm.htm. Accessed October 9, 2016.