Abstract 3287: Association Between Morphologic Appearance on Echocardiography and Histopathology in Hypertrophic Obstructive Cardiomyopathy
Background: Hypertrophic cardiomyopathy (HCM) patients with dynamic left ventricular outflow tract obstruction (LVOTO) morphologically present with reverse septal curvature (RSC), sigmoid septum (SS) or concentric hypertrophy (CH). On histopathology (HP), there is presence of myocyte disarray (MD) and small intramural coronary arteriole dysplasia (SICAD), with associated interstitial fibrosis and myocyte hypertrophy. We sought to determine the association between these morphologic subtypes and various HP findings.
Methods: We studied 209 consecutive symptomatic patients with suspected HCM and dynamic LVOTO (51% men, age 54±14 years), referred for surgical myectomy between 1/07–7/08. Diagnosis of HCM was established in presence of hypertrophied LV, out of proportion to other diseases. Morphologic LV appearance was classified on baseline echocardiogram, using the ratio of basal 1/3rd of septum to posterior wall: RSC = ratio >1.3 (extending also to the mid septum), SS = ratio >1.3 (extending only to basal 1/3rd) and concentric = ratio ≤1.3. Maximal (resting or provokable) LVOT gradient and mitral regurgitation were recorded. HP findings were also recorded.
Results: Clinical, echocardiographic and HP findings are shown in Table 1⇓. Patients with SS/CH were older and hypertensive, while those with RSC had greater basal septal thickness. On multivariable logistic regression analysis, RSC significantly predicted MD or SICAD on HP (Wald χ2 statistic 7.9 for both, p-values for both 0.005, respectively).
Conclusion: Greater proportion of HCM patients with RSC have characteristic HP findings. However, these findings are also frequently seen in older patients with dynamic LVOTO and SS/CH. Hence, these HP features, considered characteristic of “classic HCM with RSC”, appear to be nonspecific. Further studies are necessary to determine if these findings are also associated with other known causes of hypertrophy, such as hypertensive heart disease of elderly.