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

Abstract

A localized hypertrophy of the subaortic segment of the ventricular septum - ventricular septal bulge (VSB) - has been frequently described in series of elderly persons, 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 26–95 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<.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% CI 1.03–1.10, p=0.0001). After multiple adjustments, participants with VSB as compared to 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 per minute, 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, determines enhanced left ventricular contractility, without any evident impact on exercise capacity.

Distinguishing ventricular septal bulge versus hypertrophic cardiomyopathy in the elderly

“…Indeed, in contemporary adult HCM populations, prevalence of hypertension ranges from 20% to 60% 20 21 23 25–29. The prevalence of hypertension in VSB observational studies ranges between 50% and 80%,1 14 15 thus slightly higher than that reported in HCM studies. However, considering that a conclusive independent association between hypertension and VSB has yet to be confirmed,1 14–16 a history of hypertension is currently of little help in differentiating VSB from HCM.…”

“…Patients with VSB did not display a sex preference,1 14 15 in contrast to HCM, which has been generally characterised by a 3:2 male predominance,6 at least at younger ages 20 21. A recent review of 969 consecutive American and Italian patients with HCM demonstrated a reversed 60% versus 30% female predominance only in patients older than 60 years of age 22.…”

“…They accounted for about 30% in a series of 277 patients with HCM,6 though this is probably an underestimate of the true prevalence 7 8 18 19. On the contrary, it is widely recognised that the prevalence of VSB increases with age,1 14 15 ranging from 4% to 8% in individuals ≥60 years of age and reaching 10% in the eighth decade of life 1 14 15. Thus, VSB seems to be diagnosed more frequently than HCM at older ages.…”

“…In general, elderly patients with HCM do present with exertional symptoms 6 7 9 30. On the contrary, the majority of VSB studies are retrospective in nature, where patients had been selected based on echocardiographic criteria and not because of their symptoms 1 14 15. Few case reports of symptomatic patients with VSB have been published in the literature 4 12.…”

“…Some Authors included subjects with sigmoid-shaped septum without hypertrophy,15 but most VSB cohorts comprised only individuals with a proximal septal wall thickness >12–13 mm,1 2 13 14 16 applying the same entry criterion used in contemporary HCM cohorts 20 21. Thus, a considerable overlap exists between the two conditions.…”