Technetium-99m sestamibi cavity/myocardium count ratio in the detection of left ventricular hypertrophy

Abstract

Background and hypothesis: Left ventricular hypertrophy (LVH) is an independent risk factor for cardiovascular mortality and morbidity. This study was designed to assess whether technetium-99m (99mTc) sestamibi cavity-to-myocardium count (c/m) ratio would differentiate LVH from normal geometry, and discriminate between the two patterns-concentric and eccentric--of LVH.

Methods: In all, 72 patients including 32 hypertensive patients with both normal 99mTc sestamibi single-photon emission computed tomography imaging and good-quality echocardiographic recordings were studied retrospectively. Four different patterns of left ventricular (LV) geometry were defined: normal (n = 47), concentric remodeling (n = 3), eccentric LVH (n = 13), and concentric LVH (n = 9).

Results: Left ventricular hypertrophy was detected in 22 of 32 hypertensive patients. The c/m ratio calculated on midventricular short-axis slices of dipyridamole-stress 99mTc sestamibi images was significantly decreased in patients with LVH compared with subjects with normal geometry (0.05 +/- 0.02 vs. 0.17 +/- 0.08, p = 0.001). A c/m ratio of <0.124 yielded a sensitivity of 86%, a specificity of 64%, and an overall diagnostic accuracy of 68% for detecting LVH. Negative correlations of c/m ratio were found to LV mass-index (r = -0.44, p = 0.004), septal width (r = -0.42, p = 0.008), posterior wall thickness (r = -0.39, p = 0.001), and relative wall thickness (r = -0.40, p = 0.001). Multiple linear regression analysis revealed that LV mass index was the single independent predictor of c/m ratio. Although both groups with concentric and eccentric LVH had a significantly lower mean c/m ratio than those with normal geometry (p = 0.01 and p = 0.01, respectively), no significant difference of c/m ratio was found between the two patterns of LVH.

Conclusion: A new index, c/m ratio on 99mTc sestamibi images, has a potential to discriminate between LVH and normal geometry in subjects free of myocardial ischemia.