Prevalence, clinical correlates, and prognosis of discrete upper septal thickening on echocardiography: the Framingham Heart Study

Abstract

The upper interventricular septum may be prominent in elderly individuals, a finding referred to as discrete upper septal thickening (DUST). We examined the prevalence, clinical and echocardiographic correlates, and prognostic significance of DUST in a community-based sample. We evaluated Framingham Study participants who underwent routine echocardiography. In 3562 Framingham Study participants (mean age 58 years, 57% women), DUST was observed in 52 participants. The clinical correlates of DUST were increasing age (odds ratio [OR] per 10 year increment 2.59, 95% confidence intervals [CI] 1.64-4.08) and systolic blood pressure (OR per SD increment 1.55, 95% CI 1.15-2.09). DUST was positively associated with left ventricular (LV) fractional shortening and mitral annular calcification but inversely with LV diastolic dimensions (P < 0.02 for all). On follow-up (mean 15 years), 732 individuals died (33 with DUST) and 560 experienced a cardiovascular disease (CVD) event (18 with DUST). Adjusting for cardiovascular risk factors, DUST was not associated with CVD or mortality risk (P > 0.30 for both). The follow-up component of our study suggests that DUST is not independently associated with adverse prognosis.

Figure 1

Exclusion criteria and derivation of study sample.

Figure 2

Schematic representation of criteria for DUST: discrete upper septal ‘knuckle’ on visual assessment, and upper septal diastolic thickness ≥1.4 cm (AA in Figure), and upper (AA)/mid-septum (BB) diastolic thickness ≥1.3 in the absence of septal wall motion abnormalities. CC represents the posterior wall.

Figure 3

Prevalence of DUST with age. No. of individuals with DUST by number of individuals in age groups (years): 55-<60: 2/2113; 60-<65: 3/386; 65-<70: 6/308; 70-<75: 17/385; 75-<80: 9/218; 80-<85: 7/107; 85 or more: 8/45.