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Young AMI

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1999;107;254-261 Myocardial Infarction in Young Patients. Introduction. Myocardial infarction in persons under the age of 45 years accounts for 6% to 10 ... – PowerPoint PPT presentation

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Title: Young AMI


1
Young AMI
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2
Introduction
  • Myocardial infarction in persons under the age of
    45 years accounts for 6 to 10 of all myocardial
    infarctions in the United States.
  • In this age group, it is predominantly a disease
    of men.
  • Unlike older patients, approximately half of
    young patients have single-vessel coronary
    disease, and in up to 20, the cause is not
    related to atherosclerosis.

3
Coronary Anatomy
  • Most young patients with MI, up to 82 in one
    study, have typical atherosclerotic coronary
    artery disease. This manifests more often as
    single-vessel disease in younger patients than in
    older patients.
  • However, approximately 20 of young patients with
    MI do not have atherosclerosis, such as cocaine
    use or anomalous coronary arteries.
  • Multivessel coronary disease appears to be
    related to the number of risk factors, especially
    for DM patients.

4
Etiology
5
Risk Factors
6
Atherosclerosis
Figure 233-5 The atherosclerotic process. A.
Artery depicting early fatty streak development.
B. 1, LDL becomes oxidized within the arterial
subendothelial space. 2, Circulating monocytes
are recruited to the subendothelial space by
chemoattractants including oxidized LDL. 3, These
monocytes undergo differentiation, becoming
macrophages, which are scavenger cells that
recognize and accumulate oxidized LDL. 4, The
lipid-laden macrophages then become foam cells,
which cluster under the endothelial lining to
form a bulge into the artery. 5, This bulge is
called a fatty streak and is the first overt sign
of atherosclerotic change. C. Cross-section of an
artery with an atherosclerotic lesion with a
narrowed lumen.
7
Cigarette Smoking
  • Smoking produces endothelial dysfunction and can
    precipitate coronary spasm.
  • Cigarette smoking appears to be the most common
    risk factor in young MI patients.
  • The extent of smoking appears to be inversely
    related to the age at which the first MI occurs.

8
Lipid Abnormalities
9
Lipid Abnormalities
  • Homozygous familial hypercholesterolemia appears
    to have the most consistent relation with
    premature atherosclerosis and MI.
  • Increased TG levels and decreased HDL cholesterol
    levels have also been reported in MI patients
    under age 45 years.

10
Lipid Abnormalities
11
Family History
  • A positive family history of coronary artery
    disease is a major risk factor for MI in young
    patients.
  • In an autopsy study of 136 infants under 1 year
    old, mean luminal narrowing in the left coronary
    artery was 1.4 times greater in infants with no
    family history.
  • Increase of the risk in young patients with
    family history may be due to inherited disorders
    of lipid metabolism, blood coagulation, or other
    genetic factors.

12
Obesity
  • Obesity, particularly the male pattern of
    centripetal or visceral fat accumulation, can
    promote an atherogenic dyslipidemia characterized
    by elevated TG, a low HDL level, and glucose
    intolerance.
  • Approximately 30 to 58 of young patients with
    coronary artery disease are obese, a
    significantly greater proportion than in older
    patients.

13
Hypertension
  • Hypertension is less common in young MI patients
    than in older patients.
  • In addition, hypertension is common in patients
    with left main coronary artery stenosis who are
    under age 45 years.

14
DM
  • A major feature of elevated cardiovascular risk
    in patients with type 2 diabetes probably relates
    to the abnormal lipoprotein profile associated
    with insulin resistance known as diabetic
    dyslipidemia.
  • The LDL particles tend to be smaller and denser
    and thus more atherogenic.
  • DM is also less likely to be associated with MI
    in young patients than in older patients.
  • Less than 10 of young patients have DM.

15
Summary
16
Non-atherosclerosis
  • 20

17
Cocaine
  • Cocaine blocks the presynaptic reuptake of
    norepinephrine and dopamine, producing an excess
    of these neurotransmitters at the site of the
    postsynaptic receptor.
  • Acutely, cocaine increases heart rate and blood
    pressure and decreases coronary blood flow
    through vasospasm, thereby leading to increased
    myocardial oxygen demand and reduced oxygen
    supply.

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20
Cocaine
  • All young patients presenting with symptoms
    suggestive of myocardial ischemia should be
    questioned about cocaine use.

21
Hypercoagulable States
22
Hypercoagulable States
  • High levels of factor VII activity or fibrinogen
    were associated with substantially increased risk
    of coronary events among men 40 to 64 years old.
  • Use of oral contraceptives, which produce a
    prothrombotic state, has been an important risk
    factor for MI in young women.

23
Hypercoagulable States
  • Decreased fibrinolytic activity as a result of
    increased levels of plasminogen activator
    inhibitor-1(PAI-1) has been reported in MI
    patients under age 45 years.
  • Deficiencies of the natural anticoagulant
    proteins, such as protein C, protein S, and
    antithrombin III are usually associated with
    venous thromboembolism.

24
Hypercoagulable States
  • Elevated plasma homocysteine levels are
    associated with coronary artery disease,
    presumably as a result of the effects of
    homocysteine on endothelial and vascular smooth
    muscle proliferation.
  • Acquired or inherited platelet disorders have
    been associated with MI in young patients.

25
Coronary Anomalies
  • Congenital coronary artery anomalies account for
    approximately 4 of MIs in young patients.
  • Several such anomalies, including a deep
    intramyocardial course, an origin from the wrong
    coronary sinus, or ostial obstruction, have been
    associated with MI and sudden death in young
    patients.

26
Others
  • Spontaneous coronary artery dissection
  • Coronary arteritis in vasculitic disorders such
    as SLE
  • Coronary aneurysms in Kawasakis disease
  • Blunt chest trauma causing coronary thrombosis or
    dissection
  • Mediastinal irradiation therapy for Hodgkins
    disease
  • Valvular abnormalities
  • Embolization from infective endocarditis

27
Prognosis
  • Young patients with MI have a more favorable
    prognosis than older patients.
  • The incidence of cardiogenic shock, stroke, and
    left ventricular dysfunction is lower in young
    patients, probably accounting for their better
    outcome.

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30
Thank you for your attention
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