Prevalence and Clinical Correlates of Aortic Dilation in Hypertrophic Cardiomyopathy

Aortic dilation has been associated with various cardiac conditions, although its prevalence and clinical correlates in hypertrophic cardiomyopathy (HCM) remain unclear.

The purposes of this study were to define the prevalence of ascending aortic dilation in a large referral population of patients with HCM and to determine clinical and echocardiographic correlates of aortic dilation.

A total of 1,698 patients with HCM underwent echocardiographic measurement of the tubular ascending aorta (proximal and midlevel) during index evaluation at a tertiary HCM referral center. End-diastolic ascending aorta dimension was indexed to body surface area, with dilation defined for the tubular ascending aorta as 2 SD above the mean (>19 mm/m²) and independently as greater than published age-, sex-, and body surface area- adjusted norms (for the sinus of Valsalva and midlevel). Aortic size and presence of aortic enlargement were correlated with clinical and echocardiographic parameters.

Tubular ascending aortic dilation >19 mm/m² was present in 303 patients with HCM (18%), and dilation above adjusted norms was present in 210 patients with HCM (13%). The median indexed tubular ascending thoracic aortic dimension was 16.5 (interquartile range, 14.8-18.2) mm/m². Indexed dimension increased linearly with age (R = 0.53, P < .0001). Women and patients with a history of systemic hypertension were more likely to have tubular aortic enlargement >19 mm/m² (29.8% vs 9.9% and 24.1% vs 10.5%, respectively, P < .0001 for both). Patients with obstructive physiology were more likely to have tubular aortic enlargement >19 mm/m² than those without resting or provocable obstruction (19.6% vs 14.4%, P = .007). Using adjusted norms, aortic enlargement was more frequent at the midlevel compared with the sinus of Valsalva (71% vs 29%), more common in patients with hypertension (15.4% vs 10.6%, P = .009), and more common in patients with paroxysmal atrial fibrillation (16.3% vs 11.5%, P = .036), but no other relationships remained statistically significant.

In this large cohort of patients with HCM, aortic dilation was common. The key correlate of tubular aortic enlargement >19 mm/m², and aortic enlargement greater than adjusted norms included a history of systemic hypertension. Given an increased prevalence of aortic dilation in HCM, further study is needed on the clinical impact of aortic dilation.