Relation of Tc-sestamibi washout with myocardial properties in patients with hypertrophic cardiomyopathy.

Background: We sought to determine the relationship between Tc-sestamibi washout and myocardial properties in hypertrophic cardiomyopathy (HCM) patients. Methods and Results: Twenty-four HCM patients underwent biventricular cardiac catheterization, with a micromanometer-tipped catheter, both at rest and during atrial pacing, echocardiography and myocardial Tc-sestamibi scintigraphy at rest. The Tc-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-sestamibi WR < 22.5%; group B of 11 patients showing Tc-sestamibi WR ≥ 22.5%. Significant correlations were observed between Tc-sestamibi WR and percentage changes in pressure half-time ( T), as well as those in the maximum first derivative LV pressure (LV d P/d t) ( r = .43, P = .033; r = −.63, P = .001). The percentage changes in LV d P/d t and those in T 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%). Conclusion: Increased Tc-sestamibi washout is associated with an impaired contractile reserve and prolonged relaxation, suggesting that myocardial Tc-sestamibi scintigraphy may be useful in noninvasively detecting the early impairment of myocardial function in HCM patients. [ABSTRACT FROM AUTHOR]