Abstract 9637: Diverse Geometric Changes Related to Dynamic Left Ventricular Outflow Tract Obstruction Without Overt Hypertrophic Cardiomyopathy

Abstract

Background: Dynamic left ventricular (LV) outflow tract (LVOT) obstruction (DLVOTO) is not infrequently observed in older individuals without overt hypertrophic cardiomyopathy (HCM). We sought to investigate associated geometric changes and then evaluate their clinical characteristics. Method: A total of 168 patients with DLVOTO, which was defined as a trans-LVOT peak pressure gradient (PG) higher than 30 mmHg at rest or provoked by Valsalva maneuver (latent LVOTO) without fixed stenosis, were studied. Patients with classical HCM, acute myocardial infarction, stress induced cardiomyopathy or unstable hemodynamics which potentially induce transient-DLVOTO were excluded. Results: Their mean age was 71±11 years and 98 (58%) patients were women. Patients were classified as pure sigmoid septum (n=14) if they had basal septal bulging but diastolic thickness less than 15 mm, sigmoid septum with basal septal hypertrophy for a thickness ≥15 mm (n=85), prominent papillary muscle (PM) (n=20) defined by visually large PMs which occluded the LV cavity during systole, or as having a small LV cavity with concentric remodeling or hypertrophy (n=49). The prominent PM group was younger, had a higher S’and lower E/e’ than other groups. In all groups, a higher peak trans-LVOT PG was related to E/e’, right atrial pressure and pulmonary arterial systolic pressure. In multivariate analysis, resting trans-LVOT PG correlated to pulmonary arterial pressure (ß=0.200, p=0.016) after adjustment for E/e’, septal thickness and right atrial pressure. Conclusion: DLVOTO develops for various reasons, and patients with prominent PMs have distinct characteristics. DLVOTO-relieving medication may potentially reduce pulmonary pressure in this group of patients.