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

Abstract

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. 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). 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. 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.