Case of the month

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Case of the month

• Dr P Arumugam
• Consultant Nuclear Physician
• Nuclear Medicine Centre
• Central Manchester University Hospitals NHS
  Foundation trust

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History

• 58 year old Female.
• Atypical chest pain.
• Status -post PCI mid LAD November 2009.LMS 50
  lesion negative on IVUS. Equivocal DSE due to
  LBBB.

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Stress /Imaging protocol

• Adenosine stress protocol (140mcg/kg/min over 4.5
  minutes) without exercise due to LBBB. No
  ischaemic symptoms reported. Maximal HR 101.
• 2 day rest/stress with Tc- Myoview 640 MBq for
  stress and rest (as per BMI)
• Stress and rest images were acquired on GE
  Millennium Hawkeye 4 camera ( 120 minutes post
  stress due to extra cardiac activity and 70
  minutes after rest injection).
• Images were reconstructed iteratively.
• Images were considered to be of good quality with
  no significant attenuation or scatter artefact.

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• Q What is your interpretation of the perfusion
  study?
• A
• Apparent (visual) stress induced cavity dilation.
• Moderate Anteroseptal reduction in perfusion post
  stress which completely normalises at rest ( 3
  /20 segments).

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Gated study screen capture
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• Q- What is your interpretation of the single
  frame captured gated study ?
• A-
• There appears to be reduced anterior and apical
  wall motion post stress (images acquired 120
  minutes post) with normal appearance at rest
  myocardial stunning.
• There is a significant difference between post
  stress and resting ejection fraction, again
  consistent with prolonged post ischaemic stunning.

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• Q What is your interpretation based on perfusion
  and wall motion assessment?
• A Presence of reversible perfusion abnormality,
  reversible wall motion abnormality and drop in
  systolic function post stress suggests
  angiographically significant disease in the LAD.

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Angiographic findings

• Patient underwent a repeat angiogram 1 month post
  SPECT study
• Reported to show proximal LAD stenosis but patent
  mid LAD stent.
• No significant LCx, RCA or LM stenosis.
• MDT case discussed and being considered for
  single vessel CABG.

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Teaching points

• Assessment of both perfusion and function
  provides additional information.
• Regional wall motion abnormality post stress in
  ischaemic segments has been described with
  exercise1,2 myocardial imaging due to stunning.
• True ischaemia is rare with vasodilator stress as
  it induces flow heterogeneity and hence wall
  motion abnormality is not expected with adenosine
  / dipyridamole. Steal phenomenon through
  collaterals is a rare exception.

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• In a recent publication 3 however, 1/3rd of
  patients had post vasodilator stress wall motion
  abnormalities which was proportional to the
  amount of ischaemia.
• In this patient, there is evidence of regional
  wall motion abnormality, elevated ESV and drop in
  ejection fraction post stress all consistent
  with ischaemia induced LV dysfunction.
• This may be related to critical narrowing of the
  coronary artery involved 2 and may also be an
  indicator of multi vessel disease 4.

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• SPECT images are acquired 45 60 minutes post
  stress and do not reflect a true peak stress
  ejection fraction nor regional wall motion and in
  theory ,a resting one. Hence some clinicians do
  not feel the need to perform 2 gated studies
  (i.e. at rest and post stress).
• However demonstration of wall motion abnormality
  several minutes post stress would be consistent
  with post ischemic stunning.
• As post stress gated information can be obtained
  without any additional radiation nor significant
  impact on throughput, it is useful to obtain this
  data .

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References

1. Louise Emmett et al. Reversible regional wall
   motion abnormalities on exercise
   technetium-99mgated cardiac single photon
   emission computed tomography predict high-grade
   angiographic stenoses . J Am Coll Cardiol, 2002
   39991-998
2. Sharir T, Bacher-Stier C, Dhar S, et al.
   Identification of severe and extensive coronary
   artery disease by postexercise regional wall
   motion abnormalities in Tc-99m sestamibi gated
   single photon emission computed tomography. Am J
   Cardiol 2000861171-5.
3. Druz et al. Postischemic stunning after
   adenosine vasodilator stress. Journal of Nuclear
   Cardiology 535 Volume 11, Number 5534-41
4. Lima RS, Watson DD, Goode AR, et al. Incremental
   value of combined perfusion and function over
   perfusion alone by gated SPECT myocardial
   perfusion imaging for detection of severe
   three-vessel coronary artery disease. J Am Coll
   Cardiol 20034264-70.