Club 35 Moderated Poster Session - Part B: 11/12/2013, 09:30-16:00 * Location: Moderated Poster area

Background: Left atrial (LA) dysfunction and conduction alterations are observed in hypertrophic cardiomyopathy (HCM). P wave dispersion (PWD) reflects heterogenous atrial conduction. Another non-invasive method of assessing electrical events is the measurement of intra- and interatrial conduction times by tissue Doppler imaging (TDI). The aim of this study was to evaluate PWD, the intra- and interatrial asynchrony and their relations with LA volume index (LAVI), LA ejection fraction (LAEF) and plasma NT-proBNP levels in patients with HCM. Methods: Seventy patients with HCM and age and sex matched 70 subjects were enrolled. PWD was calculated on a high resolution computer screen after the magnification of ECG recordings. LA volume at end-ventricular systole (LAVmax) and end-atrial emptying (LAVmin) was assessed by TTE. LAEF was calculated as [(LAVmax-LAVmin)/LAVmax x 100]. Intra- and interatrial electromechanical conduction times were calculated by TDI. The time intervals from initiation of the P wave on ECG to the peak of the late diastolic TDI signal (A□) at the lateral border of the mitral (mitral PA□), septal (septal PA□) and the tricuspid annulus (tricuspid PA□) were measured. Interatrial asynchrony was defined as the difference between the mitral PA□ and tricuspid PA□ intervals, while intraatrial asynchrony as the difference between septal PA□ and tricuspid PA□ intervals. Plasma NT-proBNP levels were determined. Results: PWD was significantly higher in HCM group than in controls (43.5 ± 16.29 vs 37.07 ±10.61 ms, p=0.006). PWD correlated with LAVI (r=0.348, p=0.003) and LAEF (r=-0.242, p=0.044) but not related with log NT-proBNP levels (p=0.927). In HCM group interatrial electromechanical delay (42.29 ± 17.87 vs 27.64 ± 12.27 ms, p<0.001) and intraatrial electromechanical delay (25.43 ± 17.33 vs 13.57 ± 8.43 ms, p<0.001) were longer . Both intra- and interatrial asynchrony were not associated with LAVI, but significantly correlated with LAEF (r=-0.336, p=0.004 and r=-0.256, p=0.03, respectively). Intraatrial asynchrony was directly correlated with log NT-proBNP (r=0.309, p=0.012) in HCM group, while no association was detected between interatrial asynchrony and log NT-proBNP levels (p=0.102). Conclusion: Prolonged PWD, intra- and interatrial asynchrony were observed in patients with HCM and these parameters inversely correlated with LAEF. Intraatrial asynchrony was related to NT–proBNP levels. These observations seem to be related with fragmentation and slowing of atrial conduction activity which might be a result of atrial myopathy detected in HCM.