Strictly Clinical

Strategies for preventing another MI

myocardial infarction

According to the American Heart Association, each year an estimated 635,000 Americans have a new myocardial infarction (MI) and an estimated 300,000 of them have a recurrent attack. Secondary prevention is essential for reducing this number; recurrent MI puts patients at risk for reduced quality of life, heart failure, and death.

As a nurse working on a cardiac progressive care unit, I’m a member of the team that teaches the patients about what they can do to reduce their risk of having a future MI. Our team typically consists of the physician, nurse, and a member of the cardiac rehabilitation team. After talking with the physician, I am usually the first person who speaks with the patient and his or her family about secondary prevention. I am also the person who answers the questions they did not initially think to ask the physician.

In this article, I share key points to include as part of secondary prevention of MI.

Getting off to a good start

Secondary prevention should begin when the patient is diagnosed with an MI. Both verbal and written instructions are needed since at this point both patient and family will probably be unable to adequately understand and learn new material. They are simply overwhelmed with the new information they are receiving, all that they have experienced, and the inevitable lack of sleep. Be sure to document in the health record that patients have received both verbal and written educational materials.

Secondary prevention consists of two components: lifestyle modifications and medication therapy.

Lifestyle modifications

Lifestyle modification is the first-line treatment for preventing recurrent MIs. It includes smoking cessation, physical activity, diet, weight management, and management of diabetes, lipids, and blood pressure.


Smoking cessation

For those patients who smoke, quitting is a top priority. Some patients who smoke may be reluctant to make this change or refuse to quit, but others may be eager to do whatever is needed to reduce their risk of another MI.

Explain to patients that smoking reduces the amount of oxygen delivered to the heart, increases blood pressure and heart rate, and damages blood vessels. Patients should also know that second-hand smoke increases their risk for another MI by as much as 25% to 30%. In the United States alone, one in five deaths from heart disease is directly associated with smoking.

Physical activity

Physical inactivity is a major risk factor for recurrent MI. Aerobic and muscle strengthening activities has been reported to lower the all-cause mortality among adults who have had an MI or angina by up to 46%. Physical activity also promotes appropriate levels of high-density lipoprotein (HDL), Vitamin D, apolipoprotein B, and HbA1c, which helps reduce mortality.

The American Heart Association and American College of Cardiology Foundation (AHA/ACCF) guidelines recommend 30 minutes of moderate-intensity aerobic activity for at least five days a week and for the patient to increase their daily lifestyle activities such as gardening or household work. Patients should discuss activity plans with their primary care provider before starting.

Diet

Research indicates that a diet low in fat, salt, and red meat but high in fruit, vegetables, and fiber can decrease the buildup of atherosclerosis and help prevent future MIs. The Dietary Approaches to Stop Hypertension (DASH) diet and Mediterranean diet are examples of heart healthy diets that can reduce blood pressure and improve glucose-insulin homeostasis. The Mediterranean diet also helps reduce inflammatory markers such as c-reaction protein (CRP), which are elevated in patients with heart disease.

Weight management

Obesity and being overweight put people at risk for heart disease and comorbidities such as diabetes. In association with diet modification, maintaining or achieving a beneficial weight is a key element in secondary prevention. The AHA/ACCF guidelines recommend that patients should maintain or achieve a body mass index between 18.5 and 24.9. In addition, waist circumference should be less than 35 inches for women and less than 40 inches for men.

Diabetes

Diabetes, a risk factor for coronary heart disease, affects 1 in 10 US adults with most of these cases being type 2 diabetes mellitus. Diabetes combined with smoking, high cholesterol levels, and obesity places patients at an even higher risk of having another MI,

Patients with diabetes need to be monitored regularly. The AHA/ACCF guidelines suggest an HbA1c of ≤ 7% as a target goal.

Lipid management

The AHA/ACCF guidelines recommend an untreated total cholesterol level of < 170 mg/dL for children and < 200 mg/dL for adults. Unfortunately, more than 100 million US adults 20 years or older had total cholesterol levels ≥ 200 mg/dL, according to data gathered from 2009 to 2012. ACC/AHA recommends a baseline lipid measurement, a recheck in one to three months after statin therapy has been initiated, and then annually.

Diet and exercise is always the first line of treatment for an abnormal cholesterol profile. If, however, satisfactory change can’t be achieved by lifestyle changes in diet and activity, the AHA/ACCF guidelines recommend the use of statin therapy to achieve an LDL level of less than 100 mg/dL, and an LDL less than 70 mg/dL.

Blood pressure

Hypertension constricts arteries and blood vessels, which elevates a patient’s risk for another MI. A good way to describe this to a patient is to use the analogy of placing a thumb at the end of a water hose to increase water pressure.

Blood pressure screening is important because patients may not be aware that they have a problem. The 2014 Eighth Joint National Committee (JNC 8) guidelines recommend that patients who are 60 years or older should have a goal systolic blood pressure of < 150 mm Hg and diastolic blood pressure < 90 mm Hg. Patients who are younger than 60, those who are l8 or older and have chronic kidney disease, and those who are 18 or older and have diabetes are recommended to have a goal systolic blood pressure < 140 mm Hg and diastolic blood pressure < 90 mm Hg.

If diet and exercise don’t resolve high blood pressure, an antihypertensive medication will need to be added. Thiazide-type diuretics, ace inhibitors, angiotensin receptor blocker, and calcium channel blockers are examples of the different classes of drugs that are recommended to treat hypertension. Various factors influence the choice, including the presence of kidney dysfunction.

Metabolic syndrome

Patients are diagnosed with metabolic syndrome if they have three out of five of these risk factors: diabetes, low HDL, high triglycerides, increased waist circumference, and high blood pressure. Managing these conditions reduces risk for another MI.

Medications

If lifestyle modifications fail, medications are the next line of treatment for certain conditions. In addition, other medications may be added for specific reasons, such as an antiplatelet after stent placement. Possible medications include antiplatelets, P2Y12 receptor inhibitors, statins, beta-blockers, angiotensin-converting-enzyme (ACE) inhibitors, or angiotensin II receptor blockers (ARBs).

Antiplatelets/P2Y12 receptor inhibitors

Patients who have had an MI are typically placed on a daily dose of 75 to 325 mg aspirin unless contraindicated. Those who have had stent placement or have an acute coronary syndrome are also placed on a P2Y12 receptor antagonist such as clopidogrel (Plavix), prasugrel (Effient), or ticagrelor (Brilinta).

These medications prevent platelet adhesion, which can lead to clot formation and another MI. In patients with a stent, they prevent platelet adhesion around the stent, which can reclose the artery and cause an MI.

Because these medications are a type of anticoagulant, tell patients they may bruise and bleed a little easier than they did before taking the medication. Advise them to contact their primary care provider if they notice signs of bleeding, such as blood in the stool.

Statins

As mentioned, statins are used to manage lipids when lifestyle modification is not enough. An adverse effect of statin drugs is muscle pain or soreness.

Beta blockers

Beta blockers are part of the secondary prevention guidelines for patients who have had an MI or have left ventricular systolic dysfunction with an ejection fraction of ≤ 40%.

Beta-blockers are considered cardioprotective because they reduce the risk for ventricular fibrillation, which in turn can cause ischemia or infarction. The names of beta blockers end in the letters “lol,” such as carvedilol.

Beta-blockers also lower blood pressure and heart rate, so patients should be monitored for their response.

ACE inhibitors and ARBs

ACE inhibitors are used in combination with beta blockers for MI patients who have a left ventricular ejection fraction of ≤  40%.

The names of ACE inhibitors end in “pril,” such as captopril. They relax blood vessels and decrease oxygen demand for the heart. ACE inhibitors can cause a dry, persistent cough. If this occurs, or the patient has a contraindication to an ACE inhibitor, a secondary option is an ARB.

Cardiac rehabilitation

Cardiac rehabilitation is a key part of the AHA/ACCF guidelines. It promotes lifestyle modifications and provides education. Exercise-based cardiac rehabilitation after an MI reduces the risk of reinfarction and cardiac mortality, according to a meta-analysis of 34 randomized controlled trials.

A member of the cardiac rehabilitation team should visit patients who have experienced an MI or have had a coronary intervention before discharge. In our hospital, the team member teaches the patient about heart disease and lifestyle modifications and gives the patient information on the closest locations for cardiac rehabilitation programs.

Reducing risk

The goals of prevention efforts after an MI are to control the progression of disease, reduce the risk of a reoccurrence, and increase quality of life. This is achieved by managing cardiovascular risk factors with lifestyle modifications, medications, or both. Nurses are ideally positioned to take the lead in providing education that can help patients avoid another cardiac-related hospital stay.

Selected references

Centers for Disease Control and Prevention. Heart Disease Fact Sheet 2015.

Doyle B, Fitzsimmons D, McKeown P, et al. Understanding dietary decision-making in patients attending a secondary prevention clinic following myocardial infarction. J Clin Nurs. 2012;21(1-2):32-41.

Garg M, Khanna D. Exploration of pharmacological interventions to prevent isoproterenol-induced myocardial infarction in experimental models. Ther Adv Cardiovasc Dis. 2014;8(4):155-69.

James PA, Oparil S, Carter BL, et al. 2014 evidence-based guideline for the management of high blood pressure in adults. Report from the panel members appointed to the Eighth Joint National Committee (JNC8). JAMA. 2014;311(5):507-20.

Mozaffarian D, Benjamin EJ, Go AS, et al. Heart disease and stroke statistics—2015 update: a report from the American Heart Association. Circulation. 2015;131(24):e29 –e322.

Smith SC, Benjamin J, Bonow RO, et al. AHA/ACCF secondary prevention and risk reduction therapy for patients with coronary and other atherosclerotic vascular disease: 2011 update. A guideline from the American Heart Association and American College of Cardiology Foundation endorsed by the World Heart Federation and the Preventive Cardiovascular Nurses Association. J Am Coll Cardiol. 2011;58(23):2432-46.

Tonya M. Smith is a staff nurse in the progressive care unit at Huntsville Hospital in Huntsville, Alabama.

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