Myocardial Infarction

Myocardial infarction (MI) is caused by the complete or partial cessation of blood flow to the myocardium (Bharadwaj et al., 2020). The condition may go undetected or could lead to a medical emergency, leading to loss of life. In the U.S., the prevalence of MI is 3% among adults. The American Heart Association indicates that MI caused about 875,000 deaths in the U.S. in 2019 (Xing et al., 2020). MI has significant economic impacts on the U.S. healthcare system. In 2018, the U.S. spent $203.3 billion covering MI costs (Ojha and Dhamoon, 2022).  More indirect costs are incurred due to the loss of productivity after a patient recovers.

Etiology

MI has a complex etiology, including genetics, environment, and lifestyle. Most heart attacks are caused by coronary artery disease. In this condition, a coronary artery is blocked due to plaque, restricting blood flow in the heart. A blood clot may be formed in the heart when a plaque bursts open. Heart attacks may also be caused by Spontaneous coronary artery dissection (SCAD), certain infections, and coronary artery spasms. Unhealthy eating and lack of physical activity are important risk factors for MI (Xing et al., 2020). Additionally, a family history of heart attack has been linked with an increased risk for MI.

Epidemiology

In the United States, one person experiences MI every 40 seconds. Moreover, about 805,000 people have MI each year. One in five M.I.s is silent (Ojha and Dhamoon, 2022). Individuals are not aware of it, but the damage is done. “MI is the leading cause of death for people of most racial and ethnic groups in the U.S., including Alaska natives, African Americans, and American Indians” (Bharadwaj et al., 2020). The black community accounts for 22.6% of all deaths from heart attacks. Individuals who have high blood pressure, hypertension, and obesity are at the highest risk of developing MI.

Pathophysiology

MI is caused by the occlusion of an artery leading to the myocardium for about 20 and 40 minutes. This blockage occurs due to the buildup of materials in the blood vessel, called plaque. The plague can rupture and cause blood clots in the heart, preventing blood from flowing. The lack of adequate blood in the myocardium results in the death of tissues. Cardiac function may be greatly affected by the area affected (Xing et al., 2020). The affected tissues heal by scar formation. The imbalance between demand and oxygen supply leads to myocardial ischemia, presenting as mandibular discomfort or upper extremity pain.

Diagnosis

Healthcare providers screen patients during clinic visits to identify those at risk of MI. Diagnosis involves carrying out different tests to show how the heart is functioning. The primary test for MI diagnosis is an electrocardiogram (ECG) to show the heart’s electrical signals. This step must be done about ten minutes after the patient has arrived in the emergency department. Dynamic changes occur in the ECG waveform when an individual is experiencing acute MI. “Serial ECG monitoring can provide important clues to the diagnosis if the initial EKG is non-diagnostic at initial presentation.  Serial or continuous ECG recordings may help determine reperfusion or re-occlusion status” (Ojha and Dhamoon, 2022).  

Blood tests are conducted to detect cardiac troponins in the patient’s blood. The damage to the heart muscle cells during MI causes biomarkers to appear in the patient’s blood. “The rising and/or falling pattern of cardiac troponins (cTn) values with at least one value above the 99 percentile of upper reference limit (URL) associated with symptoms of myocardial ischemia would indicate an acute MI” (Ojha and Dhamoon, 2022). The continuous monitoring of these values at intervals of 3 hours for six straight hours can give an accurate value for MI. The rising/falling pattern is determined based on the baseline cTn value. A change of 20% in follow-up testing if the base value is elevated suggests an individual has MI (Ojha and Dhamoon, 2022).

Various imaging studies are also used to diagnose heart attacks. Magnetic resonance imaging (MRI) uses radio waves and magnetic fields to create an accurate heart image. The patient lies on a table and slides into a long, tube-like machine for a scan. MRI can show the magnitude of MI. An echocardiogram may also be used to diagnose the condition. The test helps physicians see how blood circulates in the heart. This test is accurate as it shows the specific area of the heart that has been damaged.

Treatment/Management

Acute Management

Reperfusion therapy is the primary line of treatment for all patients experiencing ischemia symptoms. If the treatment is done more than 120 minutes after ECG, “Primary percutaneous coronary intervention (PCI)” is considered over other approaches, such as fibrinolysis. MI patients experience chest pain. “The chest pain due to myocardial infarction is associated with sympathetic arousal, which causes vasoconstriction and increased workload for the ischemic heart” (Ojha and Dhamoon, 2022). Opioids are prescribed to relieve this pain. Among anxious patients, a mild anxiolytic such as benzodiazepine is administered. Patients with hypoxemia need supplemental oxygen.

Nitrates are used to relieve depressive symptoms associated with MI diagnosis. The dose is administered until side effects disappear and blood pressure is normalized. Beta-blockers are also used to reduce blood pressure and slow the heartbeat. It limits the damage to heart muscles and prevents MI in the future. Aspirin is also indicated for MI patients. It allows the blood to flow through narrowed arteries and reduces clotting. The oral loading dose for aspirin should be about 150mg and 300mg, with a maintenance dose between 75mg and 100mg daily (Ojha and Dhamoon, 2022). Other platelet inhibition medications that can be used for MI include ticagrelor, clopidogrel, and prasugrel.

Long-Term Management

Lipid-lowering treatment involves using high-intensity statins to stabilize atherosclerotic plaques and reduce low-density lipoproteins (LDLs). Aspirin is indicated for the long-term treatment of MI. The medication can help address most of the symptoms faced by MI patients. Patients with hypertension, diabetes, and systolic left ventricular dysfunction may need to use angiotensin-converting enzyme (ACE) inhibitors (Bharadwaj et al., 2020). These medications may be combined with glucose-lowering therapy for patients with diabetes to help them manage their blood sugar effectively. Beta-blockers are also used in the long term to manage blood pressure and slow heartbeat.

Lifestyle Modifications

Regular physical activity can help improve heart function. Patients should focus on vigorous physical activity for about 30 minutes at least five days a week (Bharadwaj et al., 2020). However, patients who have undergone surgery or a heart attack have activity restrictions. A healthy diet can help improve heart health. Foods with salt, sugar, and saturated fats must be avoided. Patients can consider foods such as fruits, vegetables, and lean proteins. Smoking and alcohol consumption affect heart health. As a result, patients who use cigarettes must quit smoking and avoid secondhand smoke. They should also limit alcohol intake.

Prognosis and Complications

While significant achievements have been made in developing effective treatments, MI remains a considerable public health concern, with a mortality rate of between 5% and 30% (Li et al., 2022). Most deaths occur before MI patients arrive at the healthcare facility. MI prognosis depends on the degree of fractional ejection and its effects on the heart muscle. Factors worsening MI prognosis include delayed reperfusion, advanced age, and diabetes. Depression, congestive heart failure, and low ejection fraction also worsen MI prognosis. Individuals with preserved left ventricular function are less likely to experience these complications.

Interdisciplinary Teams

MI is a complex health condition that requires collaboration among healthcare professionals to promote positive outcomes. Most hospitals have a cardiology team that provides comprehensive care for MI patients. Time treatment is the most important part of managing heart attacks among patients experiencing pain (Qizi & Farrukh, 2022). Interdisciplinary teams working in the emergency department must understand the importance of rapid triage. The nurse practitioner and primary care provider must educate patients about the importance of lifestyle modification in managing MI.

Conclusion

MI has a complex etiology, including genetics, environment, and lifestyle. Most heart attacks are caused by coronary artery disease. Thousands of people in the U.S. are diagnosed with MI annually. MI is caused by the occlusion of an artery leading to the myocardium for about 20 and 40 minutes. The lack of adequate blood in the myocardium results in the death of tissues. MI evaluation involves ECG, blood tests, and imaging studies. Reperfusion therapy is the primary line of treatment for all patients experiencing ischemia symptoms. The diagnosis and treatment of MI patients are best performed under interdisciplinary teams.