Abstract 1693: Gender Differences in Left Ventricular Parameters in a Normotensive Population: Impact of Indexation for Fat Free Mass
Gender differences in left ventricular (LV) parameters generally persist following indexation for body size using body surface area, height, or height2.7. LV mass (LVM) is strongly associated with fat-free mass (FFM) but the impact on gender differences of indexing by FFM has not been established.
Objective: To identify the impact on gender differences of indexing cardiovascular magnetic resonance (CMR) LV parameters for body size including FFM in a normotensive population.
Methods: We performed CMR in 1726 participants in the Framingham Heart Study Offspring Cohort, including 840 (age 36.7– 88.5 yrs; 336 M) subjects without HTN (no SBP > = 140 or DBP > = 90 mmHg at any cycle visit or on antihypertensive medication), no history of MI or heart failure, and no CMR wall motion abnormality. CMR was performed on a 1.5T scanner using a breath-hold steady state free precession (SSFP) sequence. Contiguous, 10mm-thick short-axis images were acquired from LV base to apex. FFM was estimated using the Kuch formula derived from bioelectric impedance measures. LV contours were manually segmented by a single expert observer and volumes and mass determined by summation of disks. Data were analyzed by sex and indexed by BSA, Ht, Ht2.7, and FFM. Sex differences were assessed by two-sample t-test.
Results: Ages were similar in men and women with men having slightly higher BP (Table⇓). Men had higher LV volumes, LVM, and cardiac output (CO) when normalized for BSA, Ht, and Ht2.7 (all p < 0.001 except p = NS for CO indexed for Ht2.7). In contrast, when normalized for FFM, women had higher LVEDV (p < 0.046), stroke volume and CO (both p < 0.001) but continued to have lower LVM (p < 0.001).
Conclusion: The direction of gender differences in LV volumes and LVM persists after indexing by BSA, Ht, and Ht2.7. Indexing by FFM reverses the direction of gender difference in LV volumes but not LVM. These data suggest that metabolic demand as reflected by FFM has differing impact on LV volumes and LVM in normotensive men and women.