Post-infarction conduction abnormalities
Synonyms and keywords:arrhythmias, ventricular septal defect, Supraventricular arrhythmias, ventricular arrhythmias, myocardial infarction, ischemic heart disease

# Overview
Acute myocardial infarction (MI) remains the leading cause of mortality all over the world. Electrical conduction abnormalities commonly complicate acute myocardial infarction, leading to a further rise in long and short term morbidities and mortality rates. 
Different types of conduction abnormalities can follow MI, with bradyarrhythmias and atrioventricular (AV) block representing the most common. Other post-MI conduction abnormalities include supraventricular arrhythmias and ventricular arrhythmias.

# Historical Perspective
- The history of myocardial infarction (MI) diagnostics has gone through a continuous evolution over the past century, when several new discoveries have contributed to remarkably increase the number of patients appropriately diagnosed with this condition.
- For the time being, acute myocardial infarction represents a history of success concerning diagnose, management and treatment, whereas it was considered a fatal disease in the beginning of the 1900s.
- The evolution of the management of acute myocardial infarction (MI) has been one of the crowning achievements of modern medicine. At the turn of the twentieth century, MI was an often-fatal condition.

# Classification
Bradyarrhythmia:
- Sinus bradycardia
Atrioventricular blocks:
- First degree AV block
- Second degree AV block
- Third degree AV block
Bundle branch blocks:
- Left bundle branch block (LBBB)
- Right bundle branch block (RBBB)
- Right bundle branch block(RBBB) with left anterior fascicular block (LAFB)
- RBBB with left posterior fascicular block (LPFB)
- Alternating bundle branch block
- Bifascicular block plus PR prolongation (trifascicular block)

# Pathophysiology
Myocardial infarction is defined as sudden ischemic death of myocardial tissue. In the clinical context, myocardial infarction is usually due to thrombotic occlusion of a coronary vessel caused by rupture of a vulnerable plaque.
Ischemia induces profound metabolic and ionic perturbations in the affected myocardium and causes rapid depression of systolic function.
Prolonged myocardial ischemia activates a "wavefront" of cardiomyocyte death that extends from the subendocardium to the subepicardium. Mitochondrial alterations are prominently involved in apoptosis and necrosis of cardiomyocytes in the infarcted heart. The adult mammalian heart has negligible regenerative capacity, thus the infarcted myocardium heals through formation of a scar. Infarct healing is dependent on an inflammatory cascade, triggered by alarmins released by dying cells. Clearance of dead cells and matrix debris by infiltrating phagocytes activates anti-inflammatory pathways leading to suppression of cytokine and chemokine signaling. Activation of the renin-angiotensin-aldosterone system and release of transforming growth factor- induce conversion of fibroblasts into myofibroblasts, promoting deposition of extracellular matrix proteins. Infarct healing is intertwined with geometric remodeling of the chamber, characterized by dilation, hypertrophy of viable segments, and progressive dysfunction. This review manuscript describes the molecular signals and cellular effectors implicated in injury, repair, and remodeling of the infarcted heart, the mechanistic basis of the most common complications associated with myocardial infarction, and the pathophysiologic effects of established treatment strategies. Moreover, we discuss the implications of pathophysiological insights in design and implementation of new promising therapeutic approaches for patients with myocardial infarction.

# Causes
- The usual cause of sudden blockage in a coronary artery is the formation of a blood clot (thrombus).
- most common cause of a myocardial infarction is the rupture of an atherosclerotic plaque on an artery supplying heart muscle.
- spontaneous coronary artery dissection (SCAD) and atherosclerosis as the cause of acute myocardial infarction (AMI), especially in young females.
- A coronary artery embolism is an uncommon non-atherosclerotic cause of acute myocardial infarction.
- Coronary occlusion secondary to vasculitis.
- Ventricular hypertrophy
- Coronary trauma.

# Differentiating myocardial infarction from other Diseases
MI must be differentiated from other diseases that cause chest pain such as :
- acute pericarditis
- Acute Mitral Regurgitation
- myocarditis
- Myopericarditis
- aortic stenosis
- aortic dissection
- Aortic Regurgitation
- Asthma
- Anxiety Disorders
- Cardiogenic Shock
- pulmonary embolism
- Mitral Valve Prolapse
- pneumonia
- pneumothorax

# Epidemiology and Demographics
The incidence/prevalence of  is approximately  per 100,000 individuals worldwide.
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In , the incidence/prevalence of  was estimated to be  cases per 100,000 individuals worldwide.
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In , the incidence of  is approximately  per 100,000 individuals with a case-fatality rate of %.
Patients of all age groups may develop .
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The incidence of  increases with age; the median age at diagnosis is  years.
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There is no racial predilection to .
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 affects men and women equally.
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 are more commonly affected by  than . The  to  ratio is approximately  to 1.
The majority of  cases are reported in .
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 is a common/rare disease that tends to affect  and .

# Risk Factors
- An abnormally high level of blood cholesterol (hypercholesterolemia)
- An abnormally low level of HDL (high-density lipoprotein), commonly called "good cholesterol"
- High blood pressure (hypertension)
- Diabetes
- Family history of coronary artery disease at an early age
- Cigarette smoking
- Obesity
- Physical inactivity (too little regular exercise)
- Age
Other Risk Factor:
- stress
- lack of exercise
- the use of certain illegal drugs, including cocaine and amphetamines
- a history of preeclampsia, or high blood pressure during pregnancy

# Screening
There is insufficient evidence to recommend routine screening for .
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According to the , screening for  is not recommended.
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# Natural History, Complications, and Prognosis
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Common complications of  include , , and .
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Prognosis is generally excellent/good/poor, and the 1/5/10-year mortality/survival rate of patients with  is approximately %.

# Diagnosis

## Diagnostic Study of Choice
The diagnosis of  is made when at least  of the following  diagnostic criteria are met: , , , and .
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The diagnosis of  is based on the  definition, which includes , , and .
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There are no established criteria for the diagnosis of .

## History and Symptoms
The majority of patients with  are asymptomatic.
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The hallmark of  is . A positive history of  and  is suggestive of . The most common symptoms of  include , , and . Common symptoms of  include , , and . Less common symptoms of  include , , and .

## Physical Examination
Patients with  usually appear . Physical examination of patients with  is usually remarkable for , , and .
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Common physical examination findings of  include , , and .
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The presence of  on physical examination is diagnostic of .
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The presence of  on physical examination is highly suggestive of .

## Laboratory Findings
An elevated/reduced concentration of serum/blood/urinary/CSF/other  is diagnostic of .
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Laboratory findings consistent with the diagnosis of  include , , and .
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 is usually normal among patients with .
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Some patients with  may have elevated/reduced concentration of , which is usually suggestive of .
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There are no diagnostic laboratory findings associated with .

## Electrocardiogram
There are no ECG findings associated with .
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An ECG may be helpful in the diagnosis of . Findings on an ECG suggestive of/diagnostic of  include , , and .

## X-ray
There are no x-ray findings associated with .
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An x-ray may be helpful in the diagnosis of . Findings on an x-ray suggestive of/diagnostic of  include , , and .
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There are no x-ray findings associated with . However, an x-ray may be helpful in the diagnosis of complications of , which include , , and .

## Echocardiography or Ultrasound
There are no echocardiography/ultrasound  findings associated with .
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Echocardiography/ultrasound  may be helpful in the diagnosis of . Findings on an echocardiography/ultrasound suggestive of/diagnostic of  include , , and .
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There are no echocardiography/ultrasound  findings associated with . However, an echocardiography/ultrasound  may be helpful in the diagnosis of complications of , which include , , and .

## CT scan
There are no CT scan findings associated with .
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 CT scan may be helpful in the diagnosis of . Findings on CT scan suggestive of/diagnostic of  include , , and .
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There are no CT scan findings associated with . However, a CT scan may be helpful in the diagnosis of complications of , which include , , and .

## MRI
There are no MRI findings associated with .
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 MRI may be helpful in the diagnosis of . Findings on MRI suggestive of/diagnostic of  include , , and .
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There are no MRI findings associated with . However, a MRI may be helpful in the diagnosis of complications of , which include , , and .

## Other Imaging Findings
There are no other imaging findings associated with .
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 may be helpful in the diagnosis of . Findings on an  suggestive of/diagnostic of  include , , and .

## Other Diagnostic Studies
There are no other diagnostic studies associated with .
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 may be helpful in the diagnosis of . Findings suggestive of/diagnostic of  include , , and .
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Other diagnostic studies for  include , which demonstrates , , and , and , which demonstrates , , and .

# Treatment

## Medical Therapy
There is no treatment for ; the mainstay of therapy is supportive care.
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Supportive therapy for  includes , , and .
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The majority of cases of  are self-limited and require only supportive care.
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 is a medical emergency and requires prompt treatment.
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The mainstay of treatment for  is .
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The optimal therapy for  depends on the stage at diagnosis.
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 is recommended among all patients who develop .
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Pharmacologic medical therapy is recommended among patients with , , and .
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Pharmacologic medical therapies for  include (either) , , and/or .
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Empiric therapy for  depends on  and .
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Patients with  are treated with , whereas patients with  are treated with .

## Surgery
Surgical intervention is not recommended for the management of .
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Surgery is not the first-line treatment option for patients with . Surgery is usually reserved for patients with either , , and 
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The mainstay of treatment for  is medical therapy. Surgery is usually reserved for patients with either , , and/or .
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The feasibility of surgery depends on the stage of  at diagnosis.
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Surgery is the mainstay of treatment for .

## Primary Prevention
There are no established measures for the primary prevention of .
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There are no available vaccines against .
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Effective measures for the primary prevention of  include , , and .
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 vaccine is recommended for  to prevent . Other primary prevention strategies include , , and .

## Secondary Prevention
There are no established measures for the secondary prevention of .
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Effective measures for the secondary prevention of  include , , and .