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This Article Full Text Full Text (PDF) All Versions of this Article: 295/6/H2522    most recent 00761.2008v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Baldwa, S. Articles by Fallavollita, J. A. Search for Related Content PubMed PubMed Citation Articles by Baldwa, S. Articles by Fallavollita, J. A.

Comparison of thallium deposition with segmental perfusion in pigs with chronic hibernating myocardium

¹Veterans Affairs Western New York Health Care System at Buffalo, ²Canandaigua Veteran Affairs Medical Center, ³Center for Research in Cardiovascular Medicine, and Departments of ⁴Medicine and ⁵Physiology & Biophysics at the University at Buffalo, Buffalo, New York

Submitted 21 July 2008 ; accepted in final form 20 October 2008

Viable, chronically dysfunctional myocardium with reduced resting flow (or hibernating myocardium) is an important prognostic factor in ischemic heart disease. Although thallium-201 imaging is frequently used to assess myocardial viability in patients with ischemic cardiomyopathy, there are limited data regarding its deposition in hibernating myocardium, and this data suggest that thallium retention may be supernormal compared with control myocardium. Accordingly, pigs (n = 7) were chronically instrumented with a 1.5 mm Delrin stenosis on the proximal left anterior descending coronary artery (LAD) to produce hibernating myocardium. Four months later, severe anteroapical hypokinesis was documented with contrast ventriculography (wall motion score, 0.7 ± 0.8; normal = 3), and microsphere measurements confirmed reduced resting flow (LAD subendocardium, 0.78 ± 0.34 vs. 0.96 ± 0.24 ml·min^–1·g^–1 in remote; P < 0.001). Absolute deposition of thallium-201 and insulin-stimulated [¹⁸F]-2 fluoro-2-deoxyglucose (FDG) were assessed over 1 h and compared with resting flow (n = 704 samples). Thallium-201 deposition was only weakly correlated with perfusion (r² = 0.20; P < 0.001) and was more homogeneously distributed (relative dispersion, 0.12 ± 0.03 vs. 0.29 ± 0.10 for microsphere flow; P < 0.01). Thus after 1 h relative thallium-201 (subendocardium LAD/remote, 0.96 ± 0.16) overestimated relative perfusion (0.78 ± 0.32; P < 0.0001) and underestimated the relative reduction in flow. Viability was confirmed by both histology and preserved FDG uptake. We conclude that under resting conditions, thallium-201 redistribution in hibernating myocardium is nearly complete within 1 h, with similar deposition to remote myocardium despite regional differences in flow. These data suggest that in this time frame thallium-201 deposition may not discriminate hibernating myocardium from dysfunction myocardium with normal resting flow. Since hibernating myocardium has been associated with a worse prognosis, this limitation could have significant clinical implications.

Thallium-201; [¹⁸F]-fluorodeoxyglucose; myocardial viability; coronary artery disease