Myocardial infarction

Myocardial Infarction
Other names	Heart attack, MI, Acute myocardial infarction (AMI)
Specialty	Cardiology
Symptoms	Chest pain, shortness of breath, nausea, vomiting, sweating, dizziness
Complications	Heart failure, arrhythmias, cardiogenic shock, pericarditis
Types	ST-elevation myocardial infarction (STEMI), Non-ST-elevation myocardial infarction (NSTEMI), Unstable angina
Causes	Atherosclerosis, coronary artery spasm, coronary artery dissection
Risk factors	Smoking, high blood pressure, high cholesterol, diabetes, obesity, family history
Diagnostic method	Electrocardiogram (ECG), blood tests (troponin, CK-MB), cardiac imaging
Prevention	Healthy diet, regular exercise, not smoking, maintaining a healthy weight, managing stress
Treatment	Aspirin, nitroglycerin, beta blockers, angiotensin-converting enzyme (ACE) inhibitors, angioplasty, coronary artery bypass grafting (CABG)
Prognosis	Variable, depending on the severity of the infarction and treatment received

Myocardial infarction

Myocardial infarction (MI), commonly known as a heart attack, occurs when blood flow to a part of the heart is blocked, causing damage to the heart muscle. The blockage is most often a result of atherosclerosis, a condition in which fatty deposits (plaques) build up in the coronary arteries, reducing blood flow to the heart. An MI can be life-threatening and requires immediate medical attention.

Symptoms

The most common symptoms of myocardial infarction include:

• Chest pain or discomfort, often described as a heavy pressure, squeezing, or tightness
• Shortness of breath
• Nausea and vomiting
• Sweating
• Dizziness or lightheadedness
• Fatigue

Symptoms can vary between individuals and may be milder or more severe. In some cases, individuals may experience a "silent" myocardial infarction, which presents with minimal or no symptoms.

Causes

The primary cause of myocardial infarction is atherosclerosis, a condition characterized by the buildup of fatty plaques within the coronary arteries. Plaques can rupture, leading to the formation of a blood clot, which blocks blood flow to the heart muscle. Other less common causes of MI include coronary artery spasm and coronary artery dissection.

Risk factors

Several factors can increase the risk of developing a myocardial infarction:

• Smoking
• High blood pressure (hypertension)
• High cholesterol
• Diabetes
• Obesity
• Family history of heart disease
• Age (older individuals are at higher risk)
• Gender (men are at higher risk than women)
• Chronic kidney disease
• Stress
• Excessive alcohol consumption

Diagnosis

Diagnosis of myocardial infarction typically involves:

Electrocardiogram (ECG): This test records the electrical activity of the heart and can identify areas of damage or abnormal rhythms. Blood tests: Troponin and CK-MB are proteins released into the bloodstream when the heart muscle is damaged. Elevated levels of these proteins can indicate a myocardial infarction. Cardiac imaging: Echocardiography, cardiac magnetic resonance imaging (MRI), or nuclear scans can help visualize the heart and assess the extent of damage.

Treatment

Treatment for myocardial infarction aims to restore blood flow to the heart and minimize damage to the heart muscle. Treatment options include:

• Aspirin: Chewable aspirin can help thin the blood and prevent further clot formation. Aspirin should be taken as soon as possible after the onset of symptoms.
• Nitroglycerin: This medication can help alleviate chest pain by relaxing the coronary arteries and improving blood flow to the heart.
• Beta blockers: These drugs reduce the workload on the heart and lower blood pressure, minimizing the risk of further heart damage.
• Angiotensin-converting enzyme (ACE) inhibitors: ACE inhibitors help relax blood vessels and lower blood pressure, improving blood flow and reducing the strain on the heart.
• Angioplasty and stent placement: In this procedure, a catheter is threaded through the blocked artery, and a balloon is inflated to compress the plaque against the arterial walls. A stent is then placed to keep the artery open.
• Coronary artery bypass grafting (CABG): In more severe cases, a CABG surgery may be performed to reroute blood flow around the blocked artery using a graft, usually taken from a vein or artery in the leg, chest, or arm.

Prevention

Preventing myocardial infarction involves managing risk factors and maintaining a heart-healthy lifestyle. Some preventive measures include:

• Eating a balanced diet rich in fruits, vegetables, whole grains, lean proteins, and healthy fats
• Regular exercise (at least 150 minutes of moderate-intensity aerobic activity per week)
• Avoiding tobacco use and limiting alcohol consumption
• Maintaining a healthy weight
• Managing stress through relaxation techniques, such as meditation, yoga, or deep breathing exercises
• Regularly monitoring blood pressure, cholesterol, and blood sugar levels

Prognosis

The prognosis for myocardial infarction depends on several factors, including the severity of the infarction, the extent of heart damage, and the effectiveness of treatment. Timely intervention and adherence to recommended lifestyle changes can greatly improve the prognosis for many individuals. However, some patients may develop complications, such as heart failure, arrhythmias, or cardiogenic shock, which can be life-threatening.

Epidemiology

Myocardial infarction is a leading cause of morbidity and mortality worldwide. The incidence of MI varies across populations and is influenced by age, gender, and socioeconomic factors. Early diagnosis and improved treatment strategies have contributed to a decline in mortality rates in recent decades, but the overall burden of MI remains high.

See also

• Angina
• Atherosclerosis
• Cardiovascular disease
• Coronary artery disease
• Heart failure