Background and Purpose

Left ventricular (LV) wall thickness increases with age. Inversely related to wall thickness, LV wall stress is a physiological index of cardiac compensation due to LV remodeling with ageing and disease. The interaction between age and sex on LV wall thickness and stress has not been well studied. We aimed to study the effects of sex and age on LV wall thickness and stress in normal subjects.

Methods

Single-centre study with prospective enrollment of volunteers without known cardiovascular disease, who all underwent cardiovascular magnetic resonance (CMR) imaging on a 3.0T scanner (Philips, Ingenia). LV end-diastolic (ED), end-systolic (ES) volumes and mass were calculated using Simpson’s method from semi-automatically derived endocardial and epicardial contours in stacks of LV short-axis cine CMR slices, with co-registered valve planes defined on LV long-axis views. Reconstructed temporally-resolved 3D endocardial and epicardial mesh coordinates were input into an in-house software (CardioWerkz) for analysis of LV regional wall thickness and peak systolic wall stress (PSWS) based on standard American Heart Association 17-segment heart model but omitting the apex, where thickness is assumed to approximate zero. PSWS was evaluated as 0.133*0.9*SBP*[(R/T)/(2+(1+T/2R)], where SBP is arm-cuff systolic blood pressure; and R and T respectively the regional LV radius and wall thickness calculated from 3D LV endocardial and epicardial geometries, where one-to-one correspondence of mesh vertices at all temporal phases were realized based on point-surface curvedness and conservation of energy. Global mean values of these parameters were compared, stratified by sex. Linear correlation analyses between age and the mean of these regional parameters were performed for the entire cohort, as well as within the male and female groups.

Results

We enrolled 210 subjects (age range 19 to 87 years; male-female ratio 111:99). Compared with males, females had significantly smaller body surface area and indexed LV volumes and mass (all P < 0.05), similar LV ejection fraction (P = NS), smaller wall thicknesses at both ED and ES phases, similar mean PSWS (P = 0.950) (Table 1), and similar regional PSWS at basal, mid and apical LV levels (Figure 1). Wall thickness correlated with age for the whole cohort, but only in females and not in males when analysis was stratified by sex (Table 2). No significant correlation was found between PSWS and age in the whole cohort, and within both male (r = -0.117, P = NS) and female groups (r = -0.065, P = NS).

Conclusion

In females without prior cardiovascular disease, mean LV wall thickness was smaller compared to males; and appeared to positively correlate with age, more so than in males. No significant difference was observed for mean PSWS between males and females, and no association was seen between mean PSWS and age, implying that noninvasive CMR-derived mean PSWS may be a suitable candidate index for early detection and longitudinal monitoring of sex- and age-independent myocardial decompensation in ageing and disease.

Acknowledgements

No acknowledgement found.

References

No reference found.