Positive Correlation between Transient Left Ventricular Dilation and Reversible Perfusion Abnormality on Dipyridamole Thallium-201 Scintigraphy

Received 1/4/2005; revised 3/9/2005; accepted 3/10/2005. For correspondence or reprints contact: Guang-Uei Hung, M.D., Department of Nuclear Medicine, Changhua Christian Hospital, 135 Nan-Shiao Street, Changhua 500, Taiwan. Tel: (886)4-7238595 ext. 3091, Fax: (886)4-7232942, E-mail: [email protected] Purpose: Transient left ventricular dilation (TLVD) during dipyridamole-stress myocardial perfusion imaging (MPI) has been postulated as an indicator of severe coronary artery disease and predictors of cardiac events. In this paper, the correlation between dipyridamole-induced TLVD and perfusion abnormalities on thallium-201 (Tl) single photon emission computed tomography (SPECT) was assessed and the underlying mechanisms of TLVD were discussed. Methods: Ninety-four consecutive patients undergoing dipyridamole-stress Tl MPI were enrolled for analysis. The myocardium was divided into 17 segments, and perfusion was scored on a 4-point scale (scores, 0-3 for normal to severe decrease). The ischemia score (IS score) and infarction score (IF score) were defined as the sum of the perfusion scores of segments with reversible and non-reversible perfusion abnormalities, respectively. TLVD was graded on a 3-point scale: D0 = no dilation; D1 = mild dilation; D2 = severe dilation. Results: Fifty-five of the total 94 patients showed TLVD; of which 43 patients were mild (D1) and 12 patients were severe (D2). The one-way ANOVA showed that IS scores were significantly different (D0 = 0.90 ± 1.39, D1 = 4.51 ± 2.15, D2 = 14.25 ± 4.48; P < 0.001) between D0, D1, and D2 groups. Post hoc tests showed that D1 group had significantly higher IS scores than D0 group (P < 0.001), and D2 group had significantly higher IS scores than D1 group (P < 0.001). There is no significant difference for IF score between the three groups (D0 = 3.28 ± 3.00, D1 = 2.44 ± 2.56, D2 = 3.08 ± 3.18; P = 0.394). Conclusion: Transient left ventricular dilation (TLVD) during dipyridamole-stress Tl imaging was significantly correlated to the extent and severity of reversible perfusion abnormality, but not to non-reversible one. These observations may suggest that dipyridamole-induced regional myocardial ischemia is responsible for the development of TLVD.