Journal Club

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Journal Club

• William M. Herndon,Jr MD FACC FASE
• January 27, 2005

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Historical perspectives

• Reversible Tl-201 defects pre CABG in CHF
  patients without angina led to improved LVEF post
  CABG
• BUT 45 of fixed Tl-201 defects pre CABG
  showed improvement post CABG with increased LVEF
  from 15 to 27
• Atkins. Am. J. Cardiol. 198046695

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Historical Perspectives

• Tl-201 Stress-Rest -Reinjection protocols
• rest only protocols
• Nitrate administration protocols
• All demonstrated ability to detect viability
  (with similar shortcomings)

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Imaging Agents

• Tl-201 Exhibits redistribution
• Tc-99m
• Sestamibi (Cardiolite)
• Tetrofosmin (Myoview)
• F-18 FDG

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Matsunari. J Nuc Med 361961,1995
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Viability Assessment

• Dobutamine echo has higher positive predictive
  value for functional recovery
• BUT Resting wall thickening ceases by echo with
  subendocardial infarct of gt20 LV thickness
• Perfusion imaging evaluates activity in entire LV
  thickness and reflects a continuum of values,
  some below threshold for functional recovery
• Revascularization below the level of functional
  recovery likely to show benefit from prognostic
  standpoint. Di Carli J Nuc Cardiol 20029229

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Comparison of Techniques
Meta-analysis showed higher sensitivity for
perfusion imaging, higher specificity for
Dobutamine echo, and slightly higher overall
accuracy for PET in predicting improvement in
regional dysfunction after revascularization. Ba
x. JACC 1997301451
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Measures of viability

• Recovery of regional function
• Recovery of global function
• Reverse remodeling
• Reduction of MR, TR, pulmonary hypertension
• Restitution of perfusion
• Recovery of cardiac reserve
• Reduction of symptoms
• Improved survival

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Viability AssessmentRemodeling

• What is most important detection of
  hibernating endocardium, hibernating epicardium,
  or scar?
• Is recovery of function the gold standard?
• Epicardial viability may prevent LV remodeling
  and arrhythmogenesis...

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Senior. Journal Nuc Cardiol 92002454

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Senior. Jour Nuc Cardiol 92002454
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Mortality Reduction
Meta-analysis of outcomes showed no differences
in techniques re mortality reduction or
unfavorable cardiac events after revascularization
. Allman. JACC 2002391151
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Transmural Hibernation
Transmural Scar
QUANTITATION
Tracer uptake is a continuous marker of how much
viability is present in a dysfunctional
area. Thresholds of uptake are markers of a
sufficient mass of myocardium to support
regional function after restoration of flow
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With Intermediate values on quantitation(such
as after NQMI)
Consider Stress-Rest Imaging Reversible defects
are more powerful predictors of functional
recovery than rest-only defects
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Emerging Modalities

• MRI -Will likely become the gold standard for
  viability where available
• -Assesses myocardial fibrosis
  
• - Unparalleled tissue
  characterization
• Metabolic Imaging ? ACE

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Caveats

• Severe LV dysfunction (less than 25 LVEF)
• Concomitant valvular heart disease or PHT
• Local expertise and experience may dictate best
  diagnostic approach

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