Redefining the Transient Ischemic Dilation Ratio
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Transcript of Redefining the Transient Ischemic Dilation Ratio
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The Bitterroot Mountains From Kellogg Peak
Necessity is the Mother of Invention.- Plato
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Defining Transient Ischemic Dilation
• Background
• Methods
• Results
• Conclusion
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Transient Ischemic Dilation
• The ratio of the left ventricular size after
stress compared to rest
• The left ventricular size is determined
from the ungated SPECT data
• TID is the ratio of the average wall
position at stress compared to rest
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Transient Ischemic Dilation
“As such, the volumes associated with this
measurement should not be considered to
represent either end-systolic or end-
diastolic volumes alone but rather a
complex average of the two.”
Dan Berman, Rory Hachamovitch, Guido Germano and others,
as quoted in the J Nucl Med. 2004 Dec;45(12):1999-2007.
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Transient Ischemic Dilation
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Defining the “Complex Average”
• What is the contribution of the ESV?
• What is the contribution of the EDV?
• Can this complex average be derived from
the gated SPECT data?
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“When you cannot explain it in numbers, your knowledge is of a meager and unsatisfactory kind.”
– Lord Kelvin (William Thomson, 1824-1907)
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Defining Transient Ischemic Dilation
• Background
• Methods
• Results
• Conclusion
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Methods
• Retrospective review of 422 consecutive
patients
• Ischemia determined semi-quantitatively
using a 17 segment, 5 point scale
• Post-stress to rest ventricular volume
ratios correlated with ischemia
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Defining Transient Ischemic Dilation
• Background
• Methods
• Results
• Conclusion
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Ventricular Volume Ratios
- 0.04 *0.08 **0.18 **Difference
1.060.920.84Ischemia –
1.021.001.02Ischemia +
LVEFrEDVrESVr
** p < 0.01, * p < 0.05 for the presence or absence of ischemia using the independent samples t-test
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Pearson Correlation Coefficients
-0.112 *0.227 **0.259 **Ischemia
LVEFrEDVrESVr
** p < 0.01, * p < 0.05
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Partial Correlation Coefficients
Corrected for Type of Stress
-0.1239 *0.2252 **0.2560 **Ischemia
LVEFrEDVrESVr
** p < 0.001, * p < 0.05
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Partial Correlation Coefficients
Corrected for Type of Stress and Sex
-0.1319 *0.2092 **0.2504 **Ischemia
LVEFrEDVrESVr
** p < 0.001, * p < 0.05
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Partial Correlation Coefficients
Corrected for Type of Stress, Sex, and Age
-0.1191 *0.2085 **0.2427 **Ischemia
LVEFrEDVrESVr
** p < 0.001, * p < 0.05
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Optimization
• Both the ESV and EDV contain significant
correlations
• The ESV is more highly correlated than is
the EDV
• The contribution of the ESV is greater than
that of the EDV to the TID ratio
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Optimization
stress (ESV * X + EDV)
rest (ESV * X + EDV)
where X = the ESV weighing factor
What value of X will lead to the highest correlation with myocardial ischemia?
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Partial Correlation Coefficients
Controlling for Type of Stress
0.2738 **0.2761 **0.2252 **Ischemia
X = 10X = 5X = 0
stress (ESV*X + EDV) / rest (ESV*X + EDV)where X = the ESV weighing factor
** p < 0.001
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Controlling for Type of Stress
0.2
0.22
0.24
0.26
0.28
0 5 10 15 20 25 30 35 40
ESV Weighing Factor
Correlation Coeffient
Ischemia SDS
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Controlling for Type of Stress
0.2754
0.2756
0.2758
0.276
0.2762
3.4 3.8 4.2 4.6 5 5.4 5.8 6.2
ESV Weighing Factor
Correlation Coefficient
Ischemia
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Linear Regression
30.885
30.89
30.895
30.9
30.905
4.5 5.0 5.5
ESV Weighing Factor
F Score
F Score
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Defining Transient Ischemic Dilation
• Background
• Methods
• Results
• Conclusion
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Conclusion
• The ESVr, EDVr, and LVEFr all are significantly
correlated with myocardial ischemia
• The ESVr is more highly correlated with
myocardial ischemia than the EDVr or LVEFr
• The stress (ESVx5 + EDV) / rest (ESVx5 + EDV)
has the strongest correlation with myocardial
ischemia
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The “Complex Average” ?
stress ESV * 5 + stress EDVstress ESV * 5 + stress EDV
rest ESV * 5 + rest EDVrest ESV * 5 + rest EDV