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Impact of scar thickness on the assessment of viability using dobutamine echocardiography and thallium single-photon emission computed tomography

A comparison with contrast-enhanced magnetic resonance imaging

^* University of Queensland, Brisbane, Australia

View larger version (34K): [in a new window]   Figure 1 Relationship between transmural extent of scar (TES) and resting systolic function by magnetic resonance imaging (MRI) (left) and two-dimensional echocardiogram (2DE) (right). Increasing TES is associated with a significant reduction in the proportion of segments with residual wall thickening (p < 0.001 for both MRI and 2DE). Note that in the 25% to 75% TES range, over 50% of segments still have some contractile function at rest, whereas almost all segments with >75% scar have abnormal resting function.

View larger version (26K): [in a new window]   Figure 2 Relationship between transmual extent of scar (TES) and thallium (Tl) activity at late redistribution (left) and increase in wall motion score (WMS) with low-dose dobutamine (right). Thallium activity at redistribution and the degree of low-dose augmentation both decrease significantly with increasing TES (p < 0.001), with no significant difference between dobutamine echocardiography and Tl-single-photon emission computed tomography. The 60% Tl activity cut-off for viability is shown.

View larger version (122K): [in a new window]   Figure 3 Correlation between dobutamine echocardiography and thallium single-photon emission computed tomography (Tl-SPECT) in a patient demonstrating nontransmural infarction in the apical septum (long arrow) and transmural infarction of the apical lateral segment (short arrow) by contrast-enhanced magnetic resonance imaging (ceMRI). The resting echocardiogram shows akinesia of both segments, and Tl-SPECT shows a severe perfusion defect.

View larger version (53K): [in a new window]   Figure 4 Pairwise agreement in the diagnosis of segments as viable (V) and nonviable (NV) with dobutamine echocardiography (DbE), contrast-enhanced magnetic resonance imaging (ceMRI), and thallium single-photon emission computed tomography (Tl-SPECT). The top row relates to the correspondence in all 372 segments, whereas the middle and bottom rows reflect the agreement in patients studied 3 months and >3 months after infarction. Each modality demonstrated only moderate agreement with the other two, irrespective of the time since infarction.

View larger version (54K): [in a new window]   Figure 5 Proportion of segments in which the results of thallium single-photon emission computed tomography (Tl-SPECT) and dobutamine echocardiography (DbE) were concordant (viable by both tests or nonviable by both tests) in each category of transmural extent of scar (TES). The overall concordance between Tl-SPECT and DbE is similar in each category of TES, increasing with TES >75%. Most segments that are viable by DbE are viable by Tl-SPECT when there is no scar (i.e., TES 0%), with more discrepancies as TES increases (p = 0.03). Segments that are nonviable by DbE show increasing concordance with increasing TES (p < 0.0001).