REGIONAL LEFT-VENTRICULAR CONTRACTILE DYNAMICS IN HYPERTROPHIC CARDIOMYOPATHY EVALUATED BY MAGNETIC-RESONANCE-IMAGING

To assess regional myocardial function in hypertrophic cardiomyopathy (HCM), we examined systolic wall thickening (%WT) and percent change o f segmental wall area (%AR) by cine magnetic resonance imaging. We stu died 23 normal volunteers without evidence of heart disease (group 1) and 40 patients with HCM (group 2). Short-axis images of the left vent ricle were recorded at the base and the apex, and were divided into fi ve segments. There were no significant differences in %WT and %AR amon g the segments in group 1, while %WT and %AR at the apex were higher t han values for corresponding segments at the base. The patients with H CM (group 2) were classified into three groups according to end-diasto lic wall thickness: group 2a, less than 12 mm; group 2b, 12-15 mm and group 2c, greater than 15 mm. Both the %WT and %AR at the base were si gnificantly higher in group 2a than in the other groups, but were sign ificantly lower in group 2c than in group 1 or group 2a (%WT and %AR i n groups 1, 2a, 2b, and 2c, respectively: 51 +/- 29 and 19 +/- 17; 83 +/- 40 and 34 +/- 18, 47 +/- 38 and 16 +/- 14; and 32 +/- 21 and 9 +/- 8). Both %WT (40 +/- 24) and %AR (14 +/- 12) at the apex were signifi cantly lower in group 2c than in the other groups (87 +/- 45 and 38 +/ - 31 in group 1; 89 +/- 41 and 39 +/- 31 in group 2a; and 61 +/- 27 an d 24 +/- 15 in group 2b). Myocardial shortening in the normal voluntee rs was greater at the apex than at the base. In patients with HCM, reg ional myocardial function was decreased in association with the degree of hypertrophy, with the wall function of the normal segments appeari ng to be increased in a possible compensatory mechanism.