56 Inter-atrial conduction delay is associated with la size in hypertrophic cardiomyopathy

Introduction Hypertrophic cardiomyopathy (HCM) results in diastolic dysfunction and left atrial (LA) dilatation. Little is known about whether LA size or function relate to the presence of inter-atrial conduction delay (IACD). Hence, our purpose was to assess the relationship between IACD, ventricular filling and LA size & function in HCM. Methodology: Routine clinical transthoracic echocardiography (TTE) images from a specialist tertiary hospital were retrospectively analysed by a consultant imaging cardiologist and a British Society of Echocardiography accredited cardiac Clinical Scientist. Electromechanical delay (EMD) was measured from the onset of the electrocardiogram (ECG) P-wave to the onset of the A-wave on pulsed-wave Doppler waveforms from the mitral and tricuspid valves. IACD = mitral EMD – tricuspid EMD. Diastolic filling ratio = length of diastole on mitral PW Doppler / R-R interval. LA biplane ejection fraction = [(LA volume max – LA volume min) / LA volume max] x 100. Inclusion criteria; cardiologist confirmed diagnosis of HCM, adequate image quality, adequate ECG quality. Exclusion criteria; atrial fibrillation or ventricular pacing with no preceding atrial pacing or p-wave, >moderate valvular regurgitation/stenosis. Statistical analyses were performed using MedCalc. P-values Results Data from 66 HCM patients were analysed. Mean age=56±13years, 79% were male, mean body surface area=2.0±0.2m2, mean heart rate=60±8bpm. 41% of all patients (27/66) had truncated mitral A-waves. IACD (≥30ms) was present in 24/66 (36%) of patients. P-wave duration was prolonged and maximal LA volume significantly higher in patients with IACD (Table 1). However, IACD presence was not associated with a statistically significant difference in; LA ejection fraction, LA minimum volume, diastolic filling ratio, estimated filling pressure (E/e’ ratio), PR-interval nor proportion of mitral A-wave truncation (Table 1). Conclusions One third of patients with HCM have evidence of IACD, with an association to LA volume but not global LA function. The independent effect of electrical delay upon diastolic function warrants further investigation. Conflict of Interest None