Anterior Myocardial Infarction (Heart Attack)

What is Anterior Myocardial Infarction (Heart Attack)?

Heart attacks, or in medical terms, myocardial infarctions (MI), remain the main cause of death worldwide. This is due to irreversible damage to the heart muscle because of reduced blood flow from blocked heart arteries. Heart attacks are a serious yet preventable factor in sickness and death rates.

Medically, a heart attack is diagnosed by high levels of heart biomarkers, along with signs of acute myocardial ischemia. This could be seen through symptoms like chest pain, changes within an electrocardiogram (ECG) or ultrasound evidence of wall motion abnormalities. Anterior wall myocardial infarction (AWMI) specifically happens when the blood supply to the front wall of the heart is reduced due to blockage of the left anterior descending artery (LAD).

Anterior heart attacks have a higher chance of death and illness than heart attacks in other locations. These heart attacks tend to result in more deaths in the hospital, a significant reduction in the ability of the left ventricle to pump blood, and a higher chance of heart failure compared to infarctions in other parts of the heart.

Anterior heart attacks can be classified based on where the blockage occurs in the left anterior descending (LAD) artery. Here are some categories:

1. Proximal LAD: Near to first septal perforator. On ECG tests, ST
   elevation is visible in leads V1-V6, I, and aVL. It might also show as a
   new bundle branch block or a fascicular block.
2. Mid-LAD: Farther from the first septal perforator but near to the first
   large diagonal branch. ECG tests reveal ST elevation in leads V1-V6, I,
   and aVL. Bundle branches are usually preserved.
3. Distal LAD: Farther from the large diagonal or the large diagonal itself. ECG tests
   show ST elevation in leads V1-V4, I, aVL, V5, or V6.

What Causes Anterior Myocardial Infarction (Heart Attack)?

“Plaque Rupture”

Atherosclerotic plaque rupture, also known as plaque fissure, is responsible for most anterior wall myocardial infarctions (AWMIs). This occurs when an atherosclerotic plaque, a fatty deposit in an artery, breaks open. It reveals substances that promote clotting which causes a clot or “thrombus” to form. This can obstruct blood flow within the artery, leading to a heart attack.

An anterior myocardial infarction, or front-of-heart heart attack, often happens because the left anterior descending artery gets blocked. This severely reduces the blood supply to the heart muscles, causing areas of the heart muscle to die due to lack of oxygen.

The clot formed due to the plaque rupture generally appears white (because it’s rich in platelets) at the site of rupture, while appearing red at the edges (made up of red blood cells and fibrin, a protein involved in the clotting of blood). Many biological components within the blood play a part in forming this clot. The breakdown of tissues around the cells, due to enzymes called matrix metalloproteinases (MMPs), is a key factor in causing plaque rupture.

MMPs facilitate the breakdown of tissue around cells, which in turn leads to positive restructuring and enlargement of the core of the plaque. As a result, the plaque continues to grow. When fibrillar collagen, a protein that provides structure to the plaque, is disrupted by MMPs, it creates a weak spot in the plaque. Moreover, processes like the death of certain cells and the breakdown of elastic tissues also contribute to plaque rupture. All these processes together play a role in the plaque rupture and subsequent clamp formation seen in conditions like anterior myocardial infarction.

“Plaque Erosion”

Plaque erosion is the second leading cause of acute coronary syndrome (a range of conditions associated with sudden, reduced blood flow to the heart). It differs from plaque rupture because it doesn’t involve the complete breakdown or fissure of the fibrous cap – the hard outer layer of the plaque.

A clot due to plaque erosion appears white and is abundant in neutrophils (a type of white blood cell), with smooth muscle cells scattered throughout. The core of the death and decay of cells in this case is small, and there’s an absence of endothelial lining (innermost layer of the blood vessels) due to cell death. This causes the blood components to come in contact with proteins like collagen, leading to the formation of a clot.

The site of plaque erosion is rich in substances like proteoglycan and hyaluronan, unlike the site of plaque rupture. Tests like optical coherence tomography can help tell the difference between plaque erosion and rupture.

“Microvascular and Coronary Spasm”

Spasm, or sudden contraction, in small blood vessels or coronary arteries is also a significant cause of acute coronary syndrome without the formation of a clot. Here, the spasms result in inadequate blood supply to the heart muscles causing them to be deprived of oxygen and nutrients, leading to a condition known as “ischemia”. This abnormal state often triggers symptoms of acute coronary syndrome.

Sometimes referred to as vasospastic angina or variant angina, these spasms can happen on their own or be caused by factors such as stress, cold temperatures, or certain medicines.

“AWMI Risk Factors”

Risk factors for anterior wall myocardial infarctions include high blood pressure, diabetes mellitus, smoking, dyslipidemia (abnormal amount of lipids in the blood), family history of early-onset heart disease, being overweight or obese, age and gender, inflammation in the body, eating a diet that’s high in glycemic index and low in fiber, high in red meat and trans-fatty acids, lack of physical activity. It’s important to keep these factors in mind as they can increase the likelihood of developing a heart condition.

Risk Factors and Frequency for Anterior Myocardial Infarction (Heart Attack)

Acute myocardial infarction, or a heart attack, becomes more common as people age, and it affects men and women differently. According to research, over a 10-year period, men aged 30 to 34 had 12.9 heart attacks per 1,000 people, and women aged 35 to 44 had 5.2 per 1,000. For people aged 55 to 64, the number of heart attacks increases 8 to 9 times. However, improvements in how we diagnose and treat heart attacks mean that fewer people are being hospitalized for them now.

Not everyone in the United States has the same risk of having a heart attack. Some states have more people having heart attacks, higher death rates from heart attacks, and shorter life expectancies overall. This is also a bigger problem in South Asian countries compared to developed countries.

Coronary artery disease (CAD), which often results in heart attacks, is a major public health issue. In 2013, about 1 in 3 deaths in the United States were due to heart diseases including CAD. For every person admitted to the hospital with a heart attack, approximately 30 people have stable angina, a condition where the heart muscle doesn’t get enough blood flow. As people get older, both men and women are more likely to have CAD. Although the number of people with CAD hasn’t gone down, fewer people are dying from heart attacks thanks to better treatment methods.

• Heart attacks are more common in some specific groups: around 33% are a specific type called anterior ST-elevation MI (STEMI).
• The rate of severe complications from heart attacks, such as cardiogenic shock, is between 5% and 15%.

Signs and Symptoms of Anterior Myocardial Infarction (Heart Attack)

Patients who experience a specific type of heart attack called an anterior wall myocardial infarction often show classic signs of angina. These symptoms are chest pains that occur either at rest or with lowered physical activity. The severity of the pain can vary, but it can be pretty intense for those who seek medical help due to unbearable discomfort or severe fatigue after the pain. Usually, this pain lasts for more than 30 minutes and can continue for hours if the blocked blood vessel is not reopened. This pain is often described as constricting, squeezing, or a heavy sensation in the chest. The chest discomfort is usually felt behind the sternum and can also spread to the shoulders, the neck, or even the left arm. Sometimes, this pain also results in a numbness or tingling sensation in the lower inner part of the arm.

It’s also important to note that women might display unusual symptoms. Some of these could include extreme nervousness, fearfulness, or even unusual behaviors like psychosis. Sometimes, signs of a systemic embolism can be seen too. Other related symptoms could include difficulty breathing, heartbeat irregularities, feeling of unease, nausea, vomiting, and excessive sweating.

The patients’ medical history should include details about the characteristics and duration of symptoms, factors that increase or decrease the intensity of the pain, and the patient’s physical capabilities. In addition, identification of risk factors like diabetes, smoking, high cholesterol levels, hypertension, obesity, prior history of coronary artery disease, family history, illicit drug use, and medication history and compliance should take place.

In physical examination, certain signs could indicate an anterior wall myocardial infarction:

• An anxious, restless appearance
• Patients clutching their chest or pressing a clenched fist against their sternum (known as Levine’s sign)
• Signs of heart failure, like cool, pale skin, excessive sweating, sitting propped up in bed, struggling to breathe, or coughing up pink, frothy sputum
• Signs of shock, including cool, clammy skin, blue discoloration of the fingernails, lips and unstable blood pressure and heart rate
• Rapid heart rate
• In cases without complications, the patient might have normal blood pressure whereas in cases of shock, the systolic blood pressure might be below 90 mmHg
• Rapid breathing could be due to stress, anxiety, or heart failure
• Jugular venous pressure is usually normal
• The patient’s carotid pulse may be weak and rapid
• In severe cases, the patient’s pulse may alternate between strong and weak beats
• Auscultation may reveal crackles in the chest, a sign of heart failure
• Precordial auscultation may reveal various signs including soft heart sounds, an extra heart sound following the “lub-dub”, or an outward movement of a misplaced left ventricle
• Possibly, a murmur indicating a hole in the ventricle or a leakage in the mitral valve might be heard

Lastly, frictional rubs may also be heard, typically appearing on the 2nd to 3rd day post-infarction, though they may range from as early as the 1st day to as late as 2 weeks after the heart attack.

Testing for Anterior Myocardial Infarction (Heart Attack)

When suspecting a heart attack in the front section of the heart, or anterior wall myocardial infarction, a few things can be looked at. An electrocardiogram (ECG), a test that records the electrical activity of your heart, is crucial. Certain patterns seen on the ECG can indicate a blockage in a specific section of the heart’s blood vessels, usually referred to as the left anterior descending artery (LAD). If parts of the ECG called ST-segments are raised or lowered, this can point towards different regions of the heart being affected. For example, ST-segment changes across the ‘leads’ (probes attached to the patient’s chest) can show potential blockage sites in the LAD artery.

There are also signs to look out for relating to different areas of the heart, depending on which ‘precordial leads’ (V1-V2 for example) show changes. So, by analyzing the changes seen in these leads, doctors can identify the exact area of the heart in danger.

The Troponin-I test is a top choice for diagnosing patients with this type of heart attack. However, doctors should not wait for the results if patients display signs of heart damage and ECG changes. If necessary, doctors can repeat this test for those suspected of acute coronary syndrome (ACS) whose initial results were normal.

Other useful tests include kidney and liver function tests, and a lipid panel. These contribute to a thorough assessment of a heart attack.

A chest X-ray is usually normal in these patients, unless they also have heart failure. If this is the case, the X-ray may show signs of fluid build-up in the lungs, which indicates a poorer outlook.

Transthoracic echocardiograms (TTE) are useful when the symptoms are not entirely clear. This test allows the doctor to observe if any part of the heart wall is moving abnormally, especially the sections supplied by the LAD artery. TTE can also identify complications, such as a rupture in the heart’s muscle wall, leaky heart valves, or formation of abnormal pouches in the heart.

Cardiovascular Magnetic Resonance (CMR) is a useful tool for patients who present late with a heart attack, as it helps assess the treatment options for the heart’s recovery. The use of an injected contrast enables doctors to highlight areas of scar tissue. Alongside this, dobutamine stress CMR allows doctors to assess the function of the heart’s muscle.

Last but not least, a transesophageal echocardiogram (TEE) comes in handy in case there’s limited view of the heart’s structures or potential complications with a TTE.

Treatment Options for Anterior Myocardial Infarction (Heart Attack)

The treatment of heart attacks focuses on stabilizing the patient, relieving pain, ensuring there’s an adequate supply of oxygen, reducing the demands on the heart, and restoring blood flow to the heart as soon as possible.

In patients experiencing chest pain indicative of a heart attack, nitroglycerin tablets placed under the tongue can alleviate symptoms and improve blood flow to the heart. If the chest pain continues, or relief is not adequate, nitroglycerin may be given intravenously for more sustained vasodilation. However, it should be avoided in patients with low blood pressure, slow heart rate, suspected right ventricle heart attack, and those who have taken certain medications within the previous 24 hours.

Ensuring adequate oxygen supply to the heart is crucial. Therefore, if the oxygen level in the blood drops below 90%, supplemental oxygen may be given. Morphine can also be beneficial in relieving pain, reducing anxiety, and aiding in the management of fluid buildup in the lungs.

For all patients experiencing a heart attack, an initial dose of aspirin is recommended and should be continued indefinitely as part of long-term management. Antiplatelet therapy is also vital in managing heart attacks. There are a few different antiplatelet medications that can be used depending on the patient’s individual situation.

Quick reperfusion, which means restoring the blood flow to the heart, is the key treatment for heart attacks. If patients have a certain type of heart attack, a percutaneous coronary intervention (PCI), a type of non-surgical procedure, is recommended as soon as possible. The aim is to perform PCI within 90 minutes of the initial medical contact.

If the patient first visits a hospital without PCI capabilities, the goal is to transfer the patient to a hospital with PCI capabilities in under half an hour. If this transfer takes longer, a medication to dissolve blood clots should be administered within 30 minutes of arrival.

Patients with specific types of heart attacks who meet certain criteria should undergo prompt PCI. This includes those presenting symptoms for less than 12 hours, those with a definitive contraindication to clot-dissolving therapy, patients experiencing a serious heart condition called cardiogenic shock, or acute severe heart failure.

In situations where the patient is at a facility not able to perform PCI and the delay from the first medical contact to PCI is more than 120 minutes, clot-dissolving therapy is needed if the onset of symptoms is less than 12 hours. This can also apply where the onset of symptoms is 12 to 24 hours if there are signs of ongoing chest pain with potential for large heart muscle damage or instability of essential body functions.

Patients who have received successful clot-dissolving therapy may then be considered for elective PCI between 3 and 24 hours later to further assess and treat the blood vessels supplying the heart.

Anticoagulation is necessary after clot-dissolving therapy and during PCI to prevent blood clots. Patients presenting symptoms of a heart attack should also receive beta-blockers provided they don’t have any contraindications. These drugs have multiple benefits, including reducing the demands on the heart, preventing another heart attack, having antiarrhythmic effects, and improvement of heart function.

Patients should be prescribed high-intensity statin therapy, a type of medication often used to lower cholesterol, unless contraindicated. This includes drugs like atorvastatin 80 mg.

Other adjunctive therapies that play a crucial role in managing heart attacks include antiplatelet agents and medications that reduce the body’s demand for oxygen and prevent damaging changes to the heart following a heart attack. Medication that reduces mortality and health-related problems in patients with heart failure and reduced ejection fraction is also beneficial.

What else can Anterior Myocardial Infarction (Heart Attack) be?

When a doctor is trying to diagnose a heart attack that affects the front part of the heart (anterior wall myocardial infarction), they need to consider many possible conditions that could cause similar symptoms. These can include:

• A tear in the main artery leading from the heart, known as aortic dissection
• Types of chest pain due to poor blood flow to the heart, including unstable angina, stable angina, and vasospastic angina
• Takotsubo cardiomyopathy, a temporary heart condition often triggered by stress
• Damage to the heart muscle, or myocardial trauma
• A large blood clot in the lungs, known as a massive pulmonary embolism
• A dangerous buildup of air pressure in the chest, known as tension pneumothorax
• Tearing of the esophagus, the tube that carries food from the mouth to the stomach
• Painful contractions or spasms of the esophagus
• Common digestive conditions that cause heartburn, such as gastroesophageal reflux disease or peptic acid disease
• Pain in the muscles, bones, or joints in the chest area
• Inflammation of the sac surrounding the heart, known as acute pericarditis
• Inflammation of the heart muscle, or myocarditis
• A smaller blood clot in the lungs, or pulmonary embolism

Knowing this, the doctor will conduct appropriate tests to come to an accurate diagnosis.

What to expect with Anterior Myocardial Infarction (Heart Attack)

There are different classifications for hospital death rates linked to heart issues, specifically named the Killip classes:[27]

• Killip class I has a mortality rate of 6%
• Killip class II has a mortality rate of 17%
• Killip class III has a mortality rate of 38%
• Killip class IV has a mortality rate of 81%

The blockage location in the LAD artery (a major artery supplying blood to your heart), can also predict death rates at both 30 days and 1 year after a specific type of heart attack called an anterior myocardial infarction.

Here is how the mortality rates break down based on the occlusion location in the LAD artery:

• Blockage at the start of the LAD (Proximal LAD): 30-day mortality rate is 19.6% and 1-year mortality rate is 25.6%
• Blockage in the middle of the LAD (Mid LAD): 30-day mortality rate is 9.2% and 1-year mortality rate is 12.4%
• Blockage at the end of the LAD or in the diagonal branch (Distal LAD or diagonal): 30-day mortality rate is 6.8% and 1-year mortality rate is 10.2%

Research shows patients with an anterior myocardial infarction (a type of heart attack that affects the front of the heart) often have a harder time compared to those with inferior or posterior myocardial infarction (a heart attack that affects the bottom or back of the heart). Patients with an anterior myocardial infarction have a greater chance of experiencing acute heart failure, irregular heartbeats, and death.[30][31]. After leaving the hospital, these patients also often have a worse long-term outlook, particularly if they also have a condition called right bundle branch block (RBBB), which affects the heart’s electrical system.[32]

Possible Complications When Diagnosed with Anterior Myocardial Infarction (Heart Attack)

Heart attacks affecting the front wall of the heart, also known as Anterior Wall Myocardial Infarctions (AWMI), can lead to several complications. In severe AWMI, extensive heart muscle damage can significantly lower the heart’s blood-pumping ability, resulting in a condition called cardiogenic shock. This condition is associated with higher mortality rates during hospitalization.

The left side of your heart can also be severely affected during AWMI, resulting in impaired function. This can lower the heart’s efficiency, compromise its blood-pumping action, and increase the risk of heart failure.

Potential complications of AWMI are numerous, some of which include:

• Left ventricular mural thrombus: A blood clot is frequently seen in the heart’s left chamber due to the heart attack. This clot can lead to a stroke or impaired blood supply to the limbs.
• Ventricular septal rupture: A condition where a tear appears in the wall separating the left and right chambers of the heart. This scenario urgently needs surgical repair.
• Free wall rupture: This rare case is where a part of the heart’s muscle breaks open and can cause a condition where blood fills up the space around the heart, leading to instability. Immediate surgery is required in this case.
• Pericardial effusion: Fluid accumulation in the sac around the heart due to the heart’s free wall rupture. This unhealthy buildup needs draining through minimally invasive techniques or surgery.
• Acute pericarditis: This condition refers to inflammation of the protective sac around your heart due to AWMI.
• Dressler syndrome: An immune response occurring after a heart attack results in heart and lung inflammation and fever. It usually happens weeks to months after the initial heart attack.
• Sudden Cardiac Death: AWMI can elevate the risk of fatal irregular heart rhythms which may cause sudden cardiac death.
• Conduction abnormalities: AWMI can interfere with the heart’s electrical signals resulting in various abnormal heart rhythms.
• Left ventricular aneurysm: Sometimes, AWMI can lead to an abnormal bulging in the heart’s wall. This bulging can cause heart failure, irregular heart rhythms, and blood clots that can travel to other parts of the body.

Recovery from Anterior Myocardial Infarction (Heart Attack)

To prevent further incidents of acute coronary syndrome, several steps are recommended:

• Quitting smoking can significantly lower the chances of experiencing more heart-related events and can improve overall health outcomes.
• Strictly managing blood pressure can help lower the risk of more heart-related problems and slow down the progression of heart disease.
• Good blood sugar control should be achieved and maintained. A hemoglobin A1c (HbA1c) measurement under 7% is the target. This will help to lessen the risk of diabetes-related complications and improve long-term outcomes.
• Strong management of dyslipidemia, or abnormal amounts of lipids in the blood, is key for those with AWMI. Taking medications called statins is typically advised to reach wanted lipid levels, including lowering ‘bad cholesterol’ or low-density lipoprotein cholesterol (LDL-C). Doing so will hugely decrease the chances of future heart issues.
• Maintaining a healthy body weight. It’s recommended to aim for a body mass index (BMI) between 18.5 and 24.9 kg/m².

People with AWMI can greatly benefit from a structured cardiac rehabilitation program. This program includes supervised exercise training, education on leading a heart-healthy lifestyle, and emotional support. It’s designed to improve physical function, lessen symptoms, and boost overall heart health.

Preventing Anterior Myocardial Infarction (Heart Attack)

Getting immediate emergency medical attention is crucial for people suffering from a heart attack (also known as anterior myocardial infarction). Therefore, it’s recommended that an ECG test – a procedure that checks for problems with the heart’s electrical activity – be carried out within 10 minutes of arrival at the medical center.

People should be aware of top heart-health facilities in their vicinity, and the public should understand the potential lifesaving role of bystander CPR and having access to defibrillators. Choosing a management plan for the patient can depend on access to certain facilities, like those equipped for a PCI procedure. Quick action for restoring blood flow to the affected part of the heart, using procedures like PCI among others, can lead to better patient outcomes. It helps protect heart function, limit heart damage, and improve long-term survival rates.

Depression is a common issue among heart attack patients; therefore, healthcare professionals should monitor these patients for symptoms of depression and address them promptly. Offering support like counseling, support groups, or referrals to mental health professionals can help address the patient’s emotional wellness.

Strategies to improve treatment and prevention of further heart issues should be applied at several levels: at the individual patient, across the healthcare system, and at a population-wide level. The following approaches could be beneficial:

For individuals, educating patients on lifestyle changes and adherence to treatments, especially antiplatelet therapy, is key. Patients should understand the importance of weight loss, quitting smoking, regular exercise, and a healthy diet. They should also be given clear guidance on when to go back to the emergency room, and should be encouraged to participate in heart rehabilitation programs.

Healthcare system-wide strategies should aim to support and motivate patients and clinicians in managing modifiable risk factors. Systems that promote regular follow-up visits, adherence to medication, and lifestyle change monitoring can lead to better health outcomes.

At a broader, population level, the goal should be to create a community environment that promotes heart health. This can be achieved through public awareness campaigns about cardiovascular health, reducing smoking rates, promoting physical activity, and offering access to nutritious food choices—all of which can help prevent and manage heart attacks across a large scale.