Midwall mechanics in physiologic and hypertensive concentric hypertrophy

OBJECTIVE: We sought to analyze and compare midwall fractional shortening (mFS), and its relations with circumferential end-systolic stress (cESS) and relative wall thickness (RWT), among subjects with physiologic concentric left ventricular (LV) hypertrophy, patients with hypertension and concentric LV hypertrophy, and control subjects. METHODS: A total of 51 normotensive athletes and 56 young patients with hypertension and echocardiographic evidence of concentric LV hypertrophy were enrolled. In addition, 49 age- and sex-matched control subjects were recruited. LV cavity size and wall thicknesses, LV mass, RWT, cESS, and mFS were determined by echocardiography. RESULTS: The 3 groups were similar in age, sex, height, weight, body surface area, LV diameters, and conventional indices of systolic function. LV thicknesses, RWT, LV mass, and LV mass index were similarly increased in the athletes and in the hypertensive group when compared with the control subjects. A similar depression in mFS was observed in both the athletes (22.4 +/- 2.6%) and hypertensive group (22.5 +/- 3.6%) in comparison with the control group (24.5 +/- 2.5%, P =.0003). The depression in mFS was still significant after taking into account the effect of cESS, but was no more evident after indexation of mFS by RWT or LV mass. At regression analysis, the relation between mFS and cESS showed a steeper negative slope in the patients with hypertension than in the other 2 groups. CONCLUSIONS: MFS is similarly depressed in physiologic and hypertensive concentric LV hypertrophy. The depression is abolished by adjustment for RWT or LV mass, suggesting that geometric factors are the major determinants of midwall performance in both types of concentric LV hypertrophy. However, an impaired response to different values of cESS seems to exist only in hypertensive concentric LV hypertrophy, because increasing levels of cESS may be associated with more evident mFS depression in patients with hypertension than in the athletes and control subjects.