Relation of 99mTc-sestamibi washout with myocardial properties in patients with hypertrophic cardiomyopathy

We sought to determine the relationship between Tc-99m-sestamibi washout and myocardial properties in hypertrophic cardiomyopathy (HCM) patients. Twenty-four HCM patients underwent biventricular cardiac catheterization, with a micromanometer-tipped catheter, both at rest and during atrial pacing, echocardiography and myocardial Tc-99m-sestamibi scintigraphy at rest. The Tc-99m-sestamibi washout rate (WR) was calculated using initial and delayed planar images. The HCM patients were divided into two groups as follows: Group A consisted of 13 patients showing Tc-99m-sestamibi WR < 22.5%; group B of 11 patients showing Tc-99m-sestamibi WR a parts per thousand yen 22.5%. Significant correlations were observed between Tc-99m-sestamibi WR and percentage changes in pressure half-time (T (1/2)), as well as those in the maximum first derivative LV pressure (LV dP/dt (max)) (r = .43, P = .033; r = -.63, P = .001). The percentage changes in LV dP/dt (max) and those in T (1/2) were significantly more reduced in group B than in group A (P < .05). The biphasic force-frequency relation was more frequently observed in group B than in group A (82% vs. 18%). Increased Tc-99m-sestamibi washout is associated with an impaired contractile reserve and prolonged relaxation, suggesting that myocardial Tc-99m-sestamibi scintigraphy may be useful in noninvasively detecting the early impairment of myocardial function in HCM patients.