Prevalence, Clinical Correlates, and Functional Impact of Subaortic Ventricular Septal Bulge (from the Baltimore Longitudinal Study of Aging)

A localized hypertrophy of the subaortic segment of the ventricular septum—ventricular septal bulge (VSB)—has been frequently described in series of elderly population, but its prevalence with age, clinical correlates, and impact on cardiac function and exercise capacity remain uncertain. We explored these associations in a cross-sectional sample without known cardiac disease from the Baltimore Longitudinal Study of Aging. We randomly selected 700 participants (50% men, mean age 64 ± 15, range 26 to 95 years) and reviewed their echocardiograms. We identified 28 men and 21 women with VSB (7% overall prevalence). The prevalence of VSB significantly increased with age in both genders (p <0.0001). In multivariate logistic regression including hypertension and other cardiovascular risk factors, only age displayed a significant independent association with VSB (OR 1.06 per year, 95% confidence interval 1.03 to 1.10, p = 0.0001). After multiple adjustments, participants with VSB compared with those without had enhanced global left ventricular contractility (fractional shortening 41 ± 1.3 vs 38 ± 0.3%, p = 0.04; ejection fraction 71 ± 1.6 vs 67 ± 0.4%, p = 0.06; systolic velocity of the mitral annulus 8.4 ± 0.1 vs 8.9 ± 0.3, p = 0.06), and larger aortic root diameters (3.3 ± 0.06 vs 3.1 ± 0.02 cm, p = 0.02). In subgroup of participants who completed a maximal treadmill test (177 women and 196 men), those with VSB (19, 5.1%) had significantly lower peak oxygen consumption than their counterparts (19.6 ± 3.8 vs 22.9 ± 6.6 ml/kg/min, p = 0.03). However, this association was no longer significant after multiple adjustments. In conclusion, the presence of VSB is independently associated with older age and determines enhanced left ventricular contractility, without any evident impact on exercise capacity.