major achievements in nuclear cardiology
TRANSCRIPT
Journal ClubJournal Club
William M. Herndon,Jr MD FACC FASEWilliam M. Herndon,Jr MD FACC FASE
January 27, 2005 January 27, 2005
Historical perspectives:Historical perspectives:
Reversible Tl-201 defects pre CABG in Reversible Tl-201 defects pre CABG in CHF patients CHF patients without angina without angina led to led to improved LVEF post CABGimproved LVEF post CABG
BUT: 45% of “fixed” Tl-201 defects pre BUT: 45% of “fixed” Tl-201 defects pre CABG showed improvement post CABG CABG showed improvement post CABG with increased LVEF from 15% to 27%with increased LVEF from 15% to 27%
Atkins. Am. J. Cardiol. 1980;46:695Atkins. Am. J. Cardiol. 1980;46:695
Historical PerspectivesHistorical Perspectives
Tl-201 Stress-Rest -Reinjection protocols Tl-201 Stress-Rest -Reinjection protocols ““rest only” protocolsrest only” protocols Nitrate administration protocolsNitrate administration protocols
All demonstrated ability to detect viability All demonstrated ability to detect viability (with similar shortcomings) (with similar shortcomings)
Imaging AgentsImaging Agents
Tl-201: Exhibits “redistribution”Tl-201: Exhibits “redistribution” Tc-99m:Tc-99m:
Sestamibi (Cardiolite)Sestamibi (Cardiolite)
Tetrofosmin (Myoview)Tetrofosmin (Myoview)
F-18 FDGF-18 FDG
Matsunari. J Nuc Med 36:1961,1995
Viability AssessmentViability Assessment
Dobutamine echo has higher Dobutamine echo has higher positive predictive positive predictive valuevalue for for functionalfunctional recovery recovery
BUT: Resting wall thickening BUT: Resting wall thickening ceasesceases by echo with by echo with subendocardial infarct of >20% LV thicknesssubendocardial infarct of >20% LV thickness
Perfusion imaging evaluates activity in entire LV Perfusion imaging evaluates activity in entire LV thickness and reflects a continuum of values, some thickness and reflects a continuum of values, some below threshold for below threshold for functionalfunctional recovery recovery
Revascularization below the level of functional Revascularization below the level of functional recovery likely to show benefit from prognostic recovery likely to show benefit from prognostic standpoint. standpoint. Di Carli J Nuc Cardiol 2002;9:229Di Carli J Nuc Cardiol 2002;9:229
Comparison of Techniques:Comparison of Techniques:
Meta-analysis showed higher sensitivity for perfusion imaging,higher specificity for Dobutamine echo, and slightly higheroverall accuracy for PET in predicting improvement in regional dysfunction after revascularization.
Bax. JACC 1997;30:1451
Measures of viabilityMeasures of viability
Recovery of regional functionRecovery of regional function Recovery of global functionRecovery of global function Reverse remodelingReverse remodeling Reduction of MR, TR, pulmonary hypertensionReduction of MR, TR, pulmonary hypertension Restitution of perfusionRestitution of perfusion Recovery of cardiac reserveRecovery of cardiac reserve Reduction of symptomsReduction of symptoms Improved survivalImproved survival
Viability Assessment:Viability Assessment:RemodelingRemodeling
What is most important: detection of What is most important: detection of
hibernating endocardium, hibernating hibernating endocardium, hibernating
epicardium, or scar?epicardium, or scar?
Is recovery of function the “gold standard”?Is recovery of function the “gold standard”? EpicardialEpicardial viability may prevent LV viability may prevent LV
remodeling and arrhythmogenesis...remodeling and arrhythmogenesis...
Senior. Journal Nuc Cardiol 9;2002:454
Senior. Jour Nuc Cardiol 9;2002:454
Mortality Reduction:Mortality Reduction:
Meta-analysis of outcomes showed no differences in techniques re: mortality reduction or unfavorable cardiac events afterrevascularization.
Allman. JACC 2002;39:1151
Transmural Hibernation Transmural ScarTransmural Hibernation Transmural Scar
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
QUANTITATION:
With “Intermediate” values on With “Intermediate” values on quantitationquantitation
(such as after NQMI)(such as after NQMI)Consider Stress-Rest Imaging:
Reversible defects are more powerful predictors of functional recovery than rest-only defects
Emerging ModalitiesEmerging Modalities
MRI: -Will likely become the “gold standard” for MRI: -Will likely become the “gold standard” for viability where availableviability where available
-Assesses myocardial fibrosis -Assesses myocardial fibrosis - Unparalleled tissue characterization- Unparalleled tissue characterization
Metabolic Imaging: ? ACEMetabolic Imaging: ? ACE
Caveats:Caveats:
Severe LV dysfunction (less than 25% Severe LV dysfunction (less than 25% LVEF)LVEF)
Concomitant valvular heart disease or PHTConcomitant valvular heart disease or PHT Local expertise and experience may dictate Local expertise and experience may dictate
best diagnostic approachbest diagnostic approach