Background: Left ventricular mass (LV mass) is an independent prognostic indicator of cardiovascular complications, and its regression due to therapy translates to positive clinical outcomes. Good correlation of LV mass between qualitative ECG-gated SPECT (QGS) and plain 2-dimensional echocardiography (2D-Echo) has been published, and this study aims to verify if such relationship applies in the local setting.
Methods: Forty-eight patients with normal myocardial perfusion SPECT and recent (within 30 days) plain 2D-echocardiograms (both done in the Philippine Heart Center) were recruited, and the LV masses of the two modalities were compared using Pearson correlation.
Results: Data showed a significant, but weak correlation (y = 0.28x + 78.01, r = 0.53, p < 0.001) between the LV mass of the two imaging modalities, which was also observed in the Tl-201 group (n = 45; y = 0.25x + 81.60, r = 0.48, p < 0.001), but not in the Tc-99m sestamibi group (n = 3; y = 0.47x + 46.11, r = 0.59, p = 0.601). The mean LV mass by QGS (122.01 ± 24.57) is significantly smaller compared with the mean LV mass by 2D-Echo (156.41 ± 46.52), and the difference between the two procedures (mean ± SD: 38.15 ± 35.68, p<0.001) is significantly different among all subjects, and in the Tl-201 group.
Conclusion: The LV mass generated by QGS correlates with 2D-Echo estimations, but are statistically different, with QGS significantly underestimating the echocardiographic values. Post-hoc analysis showed no significant correlation of the LV masses in the non-hypertensive Tl-201 sub-group due to relatively fewer non-hypertensive subjects. The use of Tl-201 and the consequently low count, low resolution images in this study may have contributed to the disparity and relatively weaker correlation between LV mass by QGS and 2D-Echo when compared with the published studies, which used radiotracers tagged with Tc-99m.