Heart Attack
Cardiovascular disease continues to be the leading killer in the United States. It accounted for 1 of every 2.8 deaths that occurred in 2021. Fifty two percent of these cardiovascular deaths are attributable to coronary heart disease. Each year an estimated 770,000 Americans will have a new heart attack; 430,000 Americans will have a recurrent heart attack. About every 26 seconds, an American will have a coronary event; and every minute someone will die from one.
The purpose of this article is to educate the reader about heart attacks. There are five questions I hope to answer:
• What is a heart attack?
• What are the risk factors for heart attack?
• What can we do to prevent heart attacks?
• What are the symptoms of heart attack?
• What to do if someone is having a heart attack?
What is a heart attack?
A heart attack occurs when a blood vessel that feeds the heart abruptly closes. These blood vessels are called coronary arteries. They usually close because a placque within them suddenly ruptures. After a placque ruptures, a clot forms on top of the ruptured placque. If the clot obstructs the coronary artery partially this causes unstable angina, and/or a small heart attack which is referred to as a non ST elevation myocardial infarction (NSTEMI). If the clot obstructs the coronary artery completely this causes a large or massive heart attack which is referred to as a ST elevation myocardial infarction (STEMI). Small heart attacks usually do not cause much damage to the heart but they may be a warning that a massive heart attack is coming soon. Large massive heart attacks can be life threatening.
After a coronary artery abruptly closes, the heart muscle which is normally fed by that coronary artery will starve for blood and oxygen. If the coronary artery remains obstructed for too long, that heart muscle will turn into scar tissue.
Heart attacks can be life threatening because some patients’ hearts do not tolerate starving for blood and oxygen. Those patients develop abnormal heart rhythms which are called arrhythmias. Some types of arrhythmias are not compatible with life because the heart cannot pump blood efficiently while it is in a life threatening arrhythmia. This situation is called a cardiac arrest. If a patient survives an untreated heart attack they are left with a weakened heart that may predispose them to develop congestive heart failure and life threatening arrhythmias in the future. Patients with congestive heart failure experience shortness of breath because their lungs fill up with excess fluid when the weakened heart cannot pump blood efficiently.
What are the risk factors for heart attack?
There are five classic historical risk factors that physicians use to assess a patient’s risk for heart attack:
• History of Tobacco Use
• High cholesterol
• High Blood Pressure
• Diabetes Mellitus
• Family History of Atherosclerotic Disease
In addition to the five classic historical risk factors listed above there are tools available that allow us to more accurately assess an individual’s cardiovascular risk. The Framingham Risk Score is a tool which provides individuals with their calculated risk of having a heart attack over the next 10 years. It takes into account the individuals age, gender, total cholesterol, HDL cholesterol, blood pressure, history of hypertension, and smoking history. Individuals can calculate their own 10 year risk by using the Framingham Risk Score calculator which is available on the worldwide web (Google search: Framingham Risk Score).
What can we do to prevent heart attacks?
Although the risk factors for experiencing a heart attack are highly prevalent in our society, there are things we can do to prevent heart attack. Therapeutic lifestyle changes (TLC) are the foundation of heart attack prevention. TLC starts with eating a low fat and low cholesterol diet. Some individuals may need to consult with a dietician but a heart healthy diet can briefly be summarized by the five principles listed below:
eat less red meat; eat more fish or chicken
always bake, broil, or grill (never fry!)
eat more vegetables in the form of salads and steamed vegetables (no french fries and no onion rings!)
eat more whole grains rather than bleached white rice or bread
eat a piece of fruit for dessert instead of cakes or cookies
In addition to eating a low fat, low cholesterol diet, regular exercise is also an important part of TLC. Achieving the fitness level of a competitive athlete is not required to experience the lifesaving benefits of exercise. A simple regimen that includes a brisk 30 minute walk performed five to six days each week has been shown to markedly reduce the risk for cardiovascular disease.
Maintaining proper body weight is also essential. Obesity is highly prevalent in our society and contributes to the risk factors for heart attack. The body mass index (BMI) is used to estimate an individual’s ideal body weight. It is calculated by dividing a person’s body weight by their body surface area. The reader is referred to the worldwide web (www.nhlbisupport.com/bmi/) to calculate their own BMI. BMI results are categorized below:
• Healthy BMI=19-24
• Overweight BMI=25-29
• Obese BMI=30-39
• Severely Obese BMI>40
If an individual’s BMI suggests that they are overweight, they must reduce their caloric intake until their healthy BMI is achieved. Measurements of waist circumference have also proven to be a useful tool. Men need to maintain a waist circumference less than 40 inches. Women need to maintain a waist circumference less than 35 inches.
The final therapeutic lifestyle change that must occur to reduce an individual’s risk of heart attack is cessation of all tobacco products.
Physicians can help their patients lower their risk of heart attack by monitoring and treating high cholesterol levels. The bad cholesterol is called LDL. Good cholesterol is called HDL. The LDL cholesterol is our primary target. A patient’s LDL goal varies depending on their risk:
• <160 if 1 or fewer risk factors are present
• <130 if 2 or more risk factors are present and 10 year risk is <20%
• <70-100 if 2 or more risk factors are present and 10 year risk is ≥20%
Generally, if a patient’s LDL cholesterol is not at their goal, a physician will initially recommend therapeutic lifestyle changes. If a patient cannot achieve their target LDL cholesterol after 6-12 weeks of therapeutic lifestyle changes, pharmacologic therapy should be initiated. Preferably, an HMG coenzyme A reductase inhibitor (also known as “statins”) should be started. Physician’s will need to monitor the fasting lipid profile periodically and may have to titrate statin doses to achieve the target LDL cholesterol. After reaching a patient’s target LDL cholesterol, secondary targets such as Non-HDL cholesterol (calculated as total cholesterol minus HDL), HDL cholesterol, and Triglycerides may need to be addressed.
If an individual’s blood pressure is high, it must be aggressively treated to lower their risk for heart attack. For most people the ideal blood pressure is less than 140/90. For patients with diabetes, the ideal blood pressure is less than 130/85. If a physician documents high blood pressure readings on three separate measurements, blood pressure lowering medicines should be initiated.
Patient’s who have diabetes are at increased risk for heart attack. Diligent treatment is required to reduce their risk. In addition to targeting their LDL cholesterol to less than 70-100, and maintaining their blood pressure to less than 130/85, their blood sugars must be treated uncompromisingly. Fasting blood sugars should be maintained below 100 mg/dL and glycosylated hemoglobin A1C levels below 6.5-7.0.
The final recommendation that can be made to reduce an individual’s risk of heart attack is aspirin administration. Although more controversial than in the past, many experts still advise that individuals whose calculated 10 year risk of having a heart attack is greater than 10% be treated with aspirin on a daily basis as long as there are no contraindications. The ideal dose of aspirin to prevent heart attack is still controversial based on scientific studies but most physicians recommend a dose of 81 mg daily (one baby aspirin).
What are the symptoms of heart attack?
The typical symptoms of heart attack include chest pain which is usually described as a pressure or tightness. The chest pain often travels toward the jaw or down the left arm. The chest pain is frequently associated with shortness of breath, nausea, and/or a cold sweat. Please be aware that many patients experience atypical symptoms while they are experiencing a heart attack. Women are more likely to experience atypical symptoms during a heart attack than men. Therefore, physicians should consider the diagnosis of heart attack or coronary artery disease in all patients presenting with the acute onset of chest pain or shortness of breath.
What to do if someone is having a heart attack?
If an individual is experiencing symptoms that may be caused by a heart attack for more than 5 minutes they should call 9-1-1. Many heart attack patients make the mistake of enduring their symptoms at home far too long before seeking medical attention. During a heart attack an area of heart muscle (myocardium) is starving for blood and oxygen because a coronary artery has abruptly closed. As time progresses, the amount of heart muscle that is irreversibly damaged will increase; and the amount of heart muscle that is salvageable with restoration of blood flow will decrease. During a heart attack time is muscle and every minute counts! Another common mistake made by many heart attack patients is that they try to drive themselves to the hospital or they ask a family member to drive them. Emergency medical service personnel who are activated by a 9-1-1 phone call are capable of transporting heart attack patients to the hospital more quickly and safely than the patient or family members. For these reasons, an individual who is experiencing symptoms that may be caused by a heart attack for more than 5 minutes should call 9-1-1, fast! While waiting for the ambulance to arrive, the patient can chew and swallow four baby aspirin (81 mg) or one adult aspirin (325 mg).
Upon arrival to an emergency room, patients with heart attack symptoms need to be assessed promptly. Initial assessment needs to include an electrocardiogram (ECG). National guidelines recommend that patients presenting with heart attack symptoms have an ECG performed and reviewed by a physician within ten minutes of hospital arrival. Patients who are experiencing a large heart attack (STEMI) will have an obvious abnormality on their ECG which demonstrates atleast 1 mm of ST segment elevation in two contiguous leads.
If an ECG reveals that a patient is experiencing a large heart attack (STEMI), the patient needs to be treated as soon as possible to restore blood flow to the obstructed coronary artery. The patient’s chance of surviving the heart attack is improved with quicker restoration of blood flow. There are two methods of restoring blood flow through an acutely obstructed coronary artery.
The first method involves the intravenous administration of a class of medications called thrombolytics. Thrombolytics dissolve clot inside the body. Due to widespread availability, administering thrombolytics to treat patients with large heart attacks (STEMI) is considered the standard of care for many hospitals in the United States. National guidelines recommend that if thrombolytic therapy is the chosen treatment strategy, it be administered to patients with STEMI within 30 minutes of patient arrival to the hospital. Unfortunately, the thrombolytic treatment strategy is imperfect. Thrombolytics are only 50-60% effective at restoring blood flow in the acutely obstructed coronary artery. They are also associated with a 1% chance of major intracranial bleeding that usually results in a massive stroke or death.
The preferred treatment strategy to restore coronary blood flow involves a technique called percutaneous coronary intervention (PCI). PCI requires that a patient be taken to a cardiac catheterization laboratory emergently. A long thin tube called a catheter is advanced into the groin area, through the femoral artery all the way up to the heart. Contrast dye is injected directly into the blood vessels that feed the heart to obtain x-ray pictures of the coronary arteries. These pictures are called a coronary angiogram. The coronary angiogram will demonstrate the location of the acutely obstructed coronary artery. After locating the acutely obstructed coronary artery, a thin guidewire is advanced across the blockage. Next, a balloon tipped catheter with a premounted stent is advanced over the guidewire across the blockage. Then, the balloon is inflated to open the blockage and deploy the stent. A stent is a mesh stainless steel tube that creates a scaffold to keep the blood vessel open.
PCI is the preferred treatment strategy because it is more than 95% effective at restoring blood flow in an acutely obstructed coronary artery. Also, the 1% risk of massive intracranial bleeding that occurs with the thrombolytic strategy is not present with PCI. Unfortunately, the majority of hospitals in the United States do not have cardiac catheterization laboratories capable of performing PCI. Furthermore, national heart attack guidelines recommend that if the PCI strategy is chosen to treat patients with large heart attacks (STEMI), that it be performed with a Door to Balloon Time less than 90 minutes. Door to Balloon Time refers to the time that passes from the patient’s arrival to the hospital, to the moment that the balloon is inflated in the obstructed coronary artery.
Conclusions
Heart disease continues to be the leading killer in the United States. A large number of heart disease related deaths are due to heart attack. A heart attack occurs because a coronary artery becomes acutely obstructed which results in heart muscle starving for blood and oxygen. An individual can reduce his or her risk of heart attack with preventive strategies that include therapeutic lifestyle changes, cessation of all tobacco products, cholesterol management, blood pressure control, aggressive diabetes treatment, and aspirin therapy. If an individual suspects they are having a heart attack, they need to call 9-1-1, fast! Remember, time is muscle and every minute counts.