Abstract 14461: Impact of Intermittent vs Persistent Left Ventricle Outflow Tract Obstruction on Left Atrial Strain and Diastolic Function in a Young Hypertrophic Cardiomyopathy Cohort

Abstract

Background: Adolescents and young adults with hypertrophic cardiomyopathy (HCM) and persistent left ventricular outflow tract obstruction (LVOTO) have larger left atrial volume (LAV) and abnormal diastolic function and left atrial (LA) strain compared to those without resting LVOTO. It is unknown whether intermittent LVOTO with exercise results in smaller LAV and improved diastolic function and LA strain indices compared to persistent LVOTO. Methods: All HCM patients with echo and exercise stress echocardiography (ESE) from 2014-2022 at a single center were enrolled. The cohort was divided into 3 ESE hemodynamics groups: 1) No LVOTO (all gradients < 30 mmHg, n=48); 2) Intermittent LVOTO (no rest gradient, exercise ≥30 mmHg, n=41); 3) Persistent LVOTO (rest/exercise ≥30mm Hg, n=29). LAV (biplane method), LAV Z scores, LV lateral e’, lateral e’ Z scores, LA reservoir (LASr), conduit (LAScd), and contractile (LASct) strain (TOMTEC Arena AutoSTRAIN) were analyzed. For each parameter, mean values were compared across groups using one-way analysis of variance. The Bonferroni method was used to compare Group 2 to 1 and 3. Results: 118 patients (31% F, median age 17 yrs, range 7-39) formed the cohort. Mean LAV was 64.9, 65.1, and 79.5 ml in Groups 1, 2, and 3 respectively. Differences in group means were found for LAV Z score, lateral e’, lateral e’ Z score, LASr, and LAScd (all p≤0.01). In Group 2 vs 3, LAV Z score was significantly lower (0.46 v 1.89) and LV lateral e’, lateral e’ Z score, and LAScd were significantly higher (lateral e’: 13.1 v 9.0 cm/s; lateral e’ Z score: -2.0 v -3.4; LAScd: 26.0 v 21.1%) (Fig 1). LASr did not differ significantly in Group 2 vs 3. No significant differences were found in Group 2 vs 1. Conclusion: In one of the largest young HCM cohorts, intermittent obstruction was associated with smaller LAV, better diastolic indices, and higher LA conduit strain versus persistent obstruction. Longer follow-up is needed to assess change as those with intermittent LVOTO age.