Myocardial Infarction: Recognizing Early Signs and Providing Aid

Myocardial infarction (MI) is an acute condition caused by the cessation of blood flow to a part of the heart muscle, leading to its necrosis. This emergency condition requires immediate medical attention, as every minute counts to preserve life and minimize heart damage. Complications pose a particular danger, such as heart failure, which is the leading cause of mortality in patients with acute myocardial infarction [2].

What is a Myocardial Infarction and Its Danger?

Myocardial infarction occurs when one of the coronary arteries supplying the heart with blood becomes blocked, most commonly by a blood clot. This leads to oxygen deprivation and the death of heart muscle cells. The consequences of an infarction can be extremely severe, including the development of heart failure (HF), which occurs in 14-36% of patients hospitalized with acute MI [2]. Post-infarction HF develops due to a complex interaction of macrovascular obstruction, microvascular dysfunction, myocardial stunning and remodeling, inflammation, and neurohormonal activation [2]. Early cardiac remodeling, changes in ventricular geometry and structure can lead to a vicious cycle of ventricular dilation, increased wall stress, hypertrophy, and further deterioration of heart function [8].

How to Recognize an Infarction: Early Signs

Symptoms of myocardial infarction may vary, but there are typical signs that require an immediate call for an ambulance:

• Intense chest pain: Usually described as pressing, squeezing, burning, or bursting pain behind the sternum. It can radiate to the left arm, neck, lower jaw, back, or epigastric region. The pain often does not subside after taking nitroglycerin.
• Shortness of breath: A feeling of air hunger, labored breathing, which can occur even at rest.
• Cold sweat: The sudden appearance of a sticky, cold sweat.
• Nausea or vomiting: May accompany chest pain, especially in an inferior infarction.
• Dizziness or fainting: Caused by impaired cerebral blood supply.
• General weakness and anxiety: Unexplained fatigue, fear of death.

It is important to remember that in elderly people or women, symptoms may be less pronounced or atypical, for example, manifesting only as shortness of breath or discomfort in the upper abdomen [6]. Women with acute MI tend to be older and develop heart failure more frequently than men [6].

First Aid for Suspected Infarction

If the above symptoms appear, you must act immediately:

1. Call an ambulance immediately (103 or 112): Clearly describe the symptoms and provide the exact address. This is the most important step.
2. Ensure rest: Help the person assume a comfortable position, preferably semi-reclined, to reduce the load on the heart. Unbutton tight clothing.
3. Access to fresh air: Open a window or transom.
4. Aspirin: If there are no contraindications (e.g., allergies or recent bleeding), have the person chew an aspirin tablet (150-300 mg). Aspirin helps prevent blood clots from forming.
5. Nitroglycerin: If the person has previously taken nitroglycerin as prescribed by a doctor, one dose can be given under the tongue. However, if blood pressure is low or the person feels severe weakness, nitroglycerin should not be given. Re-administration is only possible if there is no effect and blood pressure is normal.
6. Stay close: Do not leave the person alone until medics arrive.

Medical Care and Treatment of Myocardial Infarction

Effective treatment of patients with acute myocardial infarction and acute heart failure requires rapid triage, accurate diagnosis, and appropriate pharmacological treatment [3]. In a hospital setting, medical care includes:

• Diagnostics: ECG, blood tests for cardiac enzymes (troponins) to confirm the diagnosis.
• Reperfusion therapy: Restoring blood flow in the blocked artery. This can be performed via percutaneous coronary intervention (angioplasty with stenting) or thrombolytic therapy (administering clot-dissolving drugs). Early revascularization is the only therapy shown to improve survival in cardiogenic shock [2, 5].
• Medical treatment:
  • Oxygen and morphine: To relieve pain and reduce the load on the heart [6].
  • Diuretics: Loop diuretics are recommended for elderly people with congestive heart failure associated with acute MI [1].
  • Beta-blockers: Early intravenous administration is indicated for patients without contraindications within 12 hours of MI onset, with ongoing or recurrent ischemic pain, and with tachyarrhythmias (e.g., atrial fibrillation with high ventricular response rate) [1]. However, early use of beta-blockers (within 24 hours) in patients with current heart failure is associated with an increased risk of cardiogenic shock and death [4]. Long-term use of beta-blockers after MI reduces the risk of recurrent infarction and death [4].
  • ACE inhibitors: Recommended in the first 24 hours for suspected acute ST-segment elevation MI in anterior leads or clinical heart failure, in the absence of severe hypotension or contraindications [1]. They are also indicated for patients with MI and left ventricular dysfunction [1].
  • Aldosterone antagonists: Early use (within 7 days) [4].
  • Other drugs: Nitroglycerin, angiotensin II receptor blockers, spironolactone, calcium channel blockers, magnesium, digoxin, and positive inotropic drugs may also be used to treat complicated MI [6].

Infarction Complications: Heart Failure and Cardiogenic Shock

Heart failure is the most frequent and dangerous complication of myocardial infarction, significantly increasing mortality [2, 4]. It can be present upon admission or develop during hospitalization [4]. Mechanisms of HF development after MI include macrovascular obstruction, microvascular dysfunction, myocardial stunning and remodeling, inflammation, and neurohormonal activation [2].

Cardiogenic shock is an extreme form of heart failure after MI, associated with very high mortality [2, 4, 5]. It occurs when the heart cannot pump enough blood to meet the body's demands. The only therapy proven to improve survival in cardiogenic shock is early revascularization [2, 5].

In addition to heart failure, mechanical complications can develop, such as acute mitral regurgitation, ventricular septal rupture, and free wall rupture [5]. These conditions require immediate diagnosis and surgical intervention [5].

Sources

1. Heart failure complicating acute myocardial infarction. (Clinics in geriatric medicine, 2000) - Heart failure complicating acute myocardial infarction.
2. The spectrum of post-myocardial infarction care: From acute ischemia to heart failure. (Progress in cardiovascular diseases, 2024) - The spectrum of post-myocardial infarction care: From acute ischemia to heart failure.
3. Acute myocardial infarction and congestive heart failure. (Emergency medicine clinics of North America, 1996) - Acute myocardial infarction and congestive heart failure.
4. Post-Myocardial Infarction Heart Failure. (JACC. Heart failure, 2018) - Post-Myocardial Infarction Heart Failure.
5. Complicated acute myocardial infarction. Heart failure, shock, mechanical complications. (Cardiology clinics, 1991) - Complicated acute myocardial infarction. Heart failure, shock, mechanical complications.
6. Heart-failure-complicating acute myocardial infarction. (Clinics in geriatric medicine, 2007) - Heart-failure-complicating acute myocardial infarction.
7. Ischemia/Infarction. (Heart failure clinics, 2012) - Ischemia/Infarction.

The information presented in this article is for informational purposes only and cannot replace professional medical advice. If you experience any symptoms indicating a myocardial infarction, seek emergency medical help immediately.