Myocardial infarction with non-obstructive coronary arteries

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Myocardial infarction with non-obstructive
coronary arteries (MINOCA)
ANWER GHANI FIBMS IRAQ
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• Acute coronary syndromes constitute a variety of
  myocardial injury presentations that include a
  subset of patients presenting with myocardial
  infarction with non-obstructive coronary arteries
  (MINOCA).

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• Myocardial infarction with non-obstructive
  coronary arteries (MINOCA) is defined by clinical
  evidence of myocardial infarction (MI) with
  normal or near-normal coronary arteries on
  angiography.

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• Gross-Sternberg SyndromeBeltrame Syndrome

• Acute myocardial infarction (MI) without
  significant coronary artery disease (CAD) was
  initially described almost 80 years ago by Gross
  and Sternberg.
• Gross H, Sternberg WH. Myocardial infarction
  without significant lesions of coronary arteries.
  Arch Intern Med. 1939 64249267.CrossrefGoogle
  Scholar
• Whereas the term myocardial infarction with
  non-obstructive coronary arteries (MINOCA) is
  recent.It has been used by Beltrame to describe
  these patients
• Beltrame JF. Assessing patients with myocardial
  infarction and non-obstructed coronary arteries
  (MINOCA). J Intern Med. 2013 273182185.Crossref
  MedlineGoogle Scholar

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• MINOCA differs from type 1 myocardial infarction
  (MI) regarding patient characteristics,
  presentation, physiopathology, management,
  treatment, and prognosis.

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• MINOCA patient characteristics differ from those
  of other Myocardial Infarction and Coronary
  Artery Disease (MI-CAD) patients because
• MINOCA subjects are younger, are more often
  female, and tend to have fewer traditional
  cardiovascular risk factors.

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• In young patients (aged lt55 years) presenting
  with AMI, MINOCA is relatively frequent,
  occurring in gt10 of the population.

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• Acute Coronary Syndrome

• The diagnosis of an acute coronary syndrome
  should be established according to the fourth
  universal definition of MI, which is
• when there is evidence of acute myocardial injury
  accompanied by clinical data suggesting acute
  myocardial ischaemia such as relevant symptoms,
  new ischaemic electrocardiogram (ECG) changes,
  loss of viable myocardium present in imaging, or
  identification of coronary thrombus.

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• Non-obstructive coronary arteries on angiography,
  is defined as no coronary artery stenosis 50
  in any potential infarct-related artery.
• Clinical criteria and biomarker behaviour of
  MINOCA remain similar to other acute coronary
  event.

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• MINOCA is not an uncommon presentation of acute
  coronary syndromes

• The prevalence of MINOCA is estimated to be 6-9
  among patients diagnosed with MI.
• With 11 in a recent prospective observational
  study.

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• MINOCA is more common in women than men.
• MINOCA patients presenting with NSTEMI than in
  those presenting with STEMI.
• Two-thirds of MINOCA subjects present
  ST-segment elevation
• MINOCA patients are younger, are more often
  female and tend to have fewer cardiovascular risk
  factors.

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• The risk of reinfarction was higher in the MICAD
  group, the risk in the MINOCA group was lower.
• The mortality was higher among the MICAD pts.
• Although the characteristics of patients with
  MINOCA and their counterparts with AMI and CAD
  (AMI-CAD) were different, the mortality rates at
  1 month (1.1 versus 0.6, P0.43) and 1 year
  (1.7 versus 2.3, P0.68) were not statistically
  different. (2)

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• MINOCA is a working diagnosis, and defining the
  aetiologic mechanism is relevant because it
  affects patient care and prognosis.

• Identification of underlying causes of MINOCA
• -optimize treatment,
• - improve prognosis,
• - promote prevention of recurrent myocardial
  infarction.

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• The prognosis is extremely variable, depending on
  the cause of MINOCA.

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Classification of myocardial injury and infarction

• Cardiac troponin is the only recommended
  biomarker for the detection of myocardial
  necrosis, and it is integral to the diagnostic
  criteria for myocardial infarction.

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Classification of myocardial injury and infarction

• Myocardial injury is defined by only one
  criterion the elevation of cardiac troponin.
• A myocardial infarction is a myocardial injury
  attributed specifically to ischemia, i.e., with
  clinical evidence of a rise in troponin and at
  least one of the following
• ischemic symptoms or electrocardiographic
  changes,
• development of pathologic Q waves,
• imaging evidence of new loss of viable myocardial
  or regional wall motion abnormalities consistent
  with ischemia, and last,
• identification of a coronary thrombus by
  angiography or autopsy.

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Classification of myocardial injury and infarction

• The classification distinguishes between type 1
  myocardial infarction due to thrombosis of an
  atherosclerotic plaque and
• type 2 myocardial infarction due to myocardial
  oxygen supply-demand imbalance in the context of
  another acute illness.
• Myocardial infarctions presenting as sudden
  death (type 3),
• or after percutaneous coronary intervention (type
  4)
• and coronary artery bypass grafting (type 5) are
  also defined.

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Classification of myocardial injury

• Acute nonischemic myocardial injuryAcute
  myocardial injury (rise and fall in biomarkers
  cTn) in the absence of a primary ischemic cause
  (ie, absence of MI)
• Chronic myocardial injuryChronic myocardial
  injury (cTn gt99th percentile URL without an acute
  change).
• Acute myocardial injury is classified where
  troponin concentrations are elevated with
  evidence of dynamic change in the absence of
  overt myocardial ischaemia, whereas in chronic
  myocardial injury troponin concentrations remain
  unchanged on serial testing.

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• The most common causes of MINOCA

• coronary plaque disease,
• coronary dissection,
• coronary artery spasm,
• coronary microvascular spasm,
• Takotsubo cardiomyopathy,
• Myocarditis,
• coronary thromboembolism,
• other forms of type 2 myocardial infarction and
  MINOCA of uncertain aetiology.

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• Mechanisms of myocardial injury

• It is now recognised that cardiac troponin may be
  released out with the context of myocardial
  ischaemia and necrosis, with several purported
  mechanisms.
• Cardiomyocytes undergo mechanical stretch in
  response to pressure or volume overload, and this
  may trigger activation of intracellular proteases
  associated with intracellular degradation of
  troponin.
• Furthermore, there is evidence that tachycardia
  may stimulate stress-responsive integrins within
  the cardiomyocyte, triggering release of intact
  cardiac troponin I from viable cardiomyocytes in
  the absence of necrosis.

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Due to multiple potential causes, MINOCA should
be considered rather as a working diagnosis after
coronary angiography and further efforts should
be taken to define the cause of MI in each
individual patient.

• The MINOCA is a working diagnosis that requires a
  further diagnostic work-up by
• invasive techniques, such as intravascular
  ultrasound (IVUS) and optical coherence
  tomography (OCT) or
• non-invasive imaging with cardiac magnetic
  resonance imaging (CMRI).

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• When it is ascertained that obstructive coronary
  artery disease has not been inadvertently
  overlooked, other coronary disorders, such as
• plaque rupture or erosion,
• Thrombosis,
• Dissection,
• spasms
• or microvascular dysfunction should be evaluated.
  
• Furthermore, myocarditis or tako-tsubo
  cardiomyopathy should be excluded by CMRI as
  non-coronary causes.

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• In the absence of relevant coronary artery
  disease, myocardial ischaemia might be triggered
  by an acute event in epicardial coronary
  arteries, coronary microcirculation, or both.

• Epicardial causes of MINOCA include coronary
  plaque disruption, coronary dissection, and
  coronary spasm.
• Microvascular MINOCA mechanisms involve
  microvascular coronary spasm, takotsubo syndrome
  (TTS), myocarditis, and coronary thromboembolism.
• Patients with elevated cardiac markers due to
  presumed myocarditis or Takotsubo were not
  included in the VIRGO registry.

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• Coronary angiography with non-significant
  coronary stenosis and left ventriculography are
  first-line tests in the differential study of
  MINOCA patients.

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• MINOCA is not a benign diagnosis, and its
  polymorphic forms differ in prognosis.

• . MINOCA care varies across centres, and future
  multi-centre clinical trials with standardized
  criteria may have a positive impact on defining
  optimal cardiovascular care for MINOCA patients.

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Epicardial causes of MINOCA

• Coronary artery disease (plaque rupture)
• DX IVUS/OCT, FFR/iFR
• RX Antiplatelet therapy, statins, ACEi/ARB,
  beta-blockers
• Studies of intracoronary imaging have shown that
  40 of patients with MINOCA have some evidence
  of plaque disruption. Since coronary angiography
  cannot evaluate the vascular lumen, intracoronary
  imaging modalities such as intravascular
  ultrasound (IVUS) might play a determinant role
  in evaluating the lesion.
• IVUS Intravascular ultrasound OCT Optical
  coherence tomography FFR Fractional flow
  reserve iFR Instantaneous wave-free ratio..
• Although intravascular ultrasound is helpful in
  demonstrating plaque rupture, optical coherence
  tomography is a better tool for identifying
  patients with plaque erosion and may be superior
  for the assessment of patients with spontaneous
  coronary artery dissection.(2)

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Epicardial causes of MINOCA

• Coronary dissection
• DX IVUS/OCT
• RX Beta-blocker and simple antiplatelet therapy.

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Epicardial causes of MINOCA

• Coronary artery spasm
• DX Intracoronary nitrates, intracoronary Ach or
  ergonovine test by experienced teams
• RX Calcium antagonists, nitrates.

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Microvascular causes of MINOCA

• Microvascular coronary spasm
• DX Objective evidence of ischaemia (ECG, LV wall
  motion abnormalities, PET). Impaired
  microvascular function (CFR, intracoronary Ach
  test, abnormal CMR, slow coronary flow)
• RX Beta-blockers and nitrates, calcium
  antagonist, possibly ranolazine
• CMR Cardiac magnetic resonance PET Positron
  emission tomography.

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Microvascular causes of MINOCA

• Takotsubo syndrome
• DX Ventriculography, echocardiography, troponin,
  B-natriuretic peptide, CMR
• RX Heart failure treatment, mechanical support
  in cardiogenic shock.

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Microvascular causes of MINOCA

• Myocarditis
• Dx CMR, EMB, viral serologies, high c-reactive
  protein
• Rx Heart failure treatment if complication,
  autoimmune therapy in autoimmune forms.
• EMB Endomyocardial biopsies.

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Microvascular causes of MINOCA

• Coronary embolism
• Dx History of potential thromboembolic sources,
  thrombophilia screen, TTE, TOE, bubble contrast
  echography
• Rx Antiplatelet therapy, anticoagulation,
  transcatheter closure or surgical repair.

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• Among patients with AMI, there is a higher
  prevalence of nonobstructive coronary arteries
  among women, particularly young women.
  Nevertheless, the prognosis for young women with
  AMI is worse than that for young men.It is
  possible that this result is due to suboptimal
  (less aggressive and/or less targeted)
  therapeutic strategies in patients with
  nonatherosclerotic AMI. (2)

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• Discharge therapies (eg, aspirin, ß-blockers,
  angiotensin-converting enzyme inhibitors and
  angiotensin receptor II blockers, and statins)
  were less frequently prescribed for MINOCA
  patients.
• Favorable outcomes when MINOCA patients were
  treated with ß-blockers, angiotensin-converting
  enzyme inhibitors and angiotensin receptor II
  blockers, and statins, but no significant
  benefits were observed with P2Y12 inhibitors.

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• Summary

• MINOCA has comparable outcomes to MI-CAD up to 1
  year of follow-up. Nevertheless, there is a
  paucity of evidence-based data to guide our
  approach to the evaluation and management of
  MINOCA patients.
• This results in variable and suboptimal practice
  patterns and disparities in care. The time has
  come to make a change!

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References

• 1- Myocardial infarction with non-obstructive
  coronary arteries A comprehensive review and
  future research directions. Rafael Vidal-Perez,
  Charigan Abou Jokh Casas, Rosa Maria
  Agra-Bermejo, Belén Alvarez-Alvarez, Julia
  Grapsa, Ricardo Fontes-Carvalho, Pedro Rigueiro
  Veloso, Jose Maria Garcia Acuña, and Jose Ramon
  Gonzalez-Juanatey. World J Cardiol. 2019 Dec 26
  11(12) 305315.
• 2- Myocardial Infarction With Nonobstructive
  Coronary Arteries (MINOCA) It's Time to Face
  Reality! Jacqueline E. Tamis-Holland, and Hani
  Jneid. Originally published28 Jun
  2018https//doi.org/10.1161/JAHA.118.009635Journal
  of the American Heart Association.
  20187e009635.
• 3- Assessment and classification of patients with
  myocardial injury and infarction in clinical
  practice. Andrew R Chapman, Philip D Adamson,
  http//orcid.org/0000-0003-1926-5925Nicholas L
  Mills.Heart 201710310-18.

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THANKS