ABSTRACTS Heart, Lung and Circulation Abstracts S51 2008;17S:S1–S209 E velocity, deceleration time (DT), IVRT, Doppler tissue imaging derived E ′ velocity are markers of ventricu- lar relaxation. E/E ′ correlates with LV filling pressures, but it is unknown if this relationship exists during ischaemia/infarction. Aim: To determine the impact of myocardial ischaemia and revascularisation on diastolic properties in subjects with STEMI. Methods: Twenty-eight consecutive patients presenting with their first STEMI, who underwent primary angio- plasty during office hours were prospectively studied with a rapid transthoracic echo protocol performed prior to pri- mary angioplasty. A comprehensive echocardiogram was performed at 3 days. LVEDP was measured prior to and following revascularization in a subset of patients. Results: The mean age of pts was 62 ± 11 years, 71% were males and anterior infarction was present in 11 patients (65%). LVEF improved following revascularisa- tion (47 ± 8% vs. 52 ± 8%; p = 0.002). Significant changes were noted in diastolic parameters following revascu- larization: Peak E-velocity decreased (77 ± 21 vs. 67 ± 15, p = 0.03) as did E ′ velocity (7 ± 2 vs. 6 ± 2, p = 0.002) while E/E ′ ratio (11 ± 2 vs. 12 ± 2, p = 0.02) and DT (168 ± 26 vs. 195 ± 47, p = 0.005) increased. No significant improvement was noted in the LVEDP immediately post-reperfusion (25.0 ± 8.1 vs. 21.3 ± 5.0 mmHg, p = 0.10). No correlation was noted between LVEDP and E/E ′ ratio during ischaemia (r = 0, p = 1.0). Conclusion: In this study, acute changes in diastolic indices were noted alongside improvement in systolic function with revascularization. E/E ′ may not correlate with LVEDP in the setting of acute ischaemia. doi:10.1016/j.hlc.2008.05.117 117 Optimal Reconstruction Phase For Demonstration of Maximal Coronary Sinus Area by Cardiac Computed Tomography Rohan Poulter ∗ , Camilla Wainwright, John F. Younger, Melanie Fuentes Royal Brisbane & Women’s Hospital, Brisbane, Australia Background: The cardiac venous system can be visualised with computed tomography (CT) prior to left ventricu- lar lead placement for cardiac resynchronisation therapy. The choice of reconstruction phase for CT coronary artery imaging relies on selecting the period of minimum cardiac motion, typically at end-diastole (70% of the cardiac cycle). The use of dose modulation, while limiting radiation dose, requires the prediction of the ideal reconstruction phase prior to scanning. However the diastolic phase may not be optimal for venous imaging due to changes in venous luminal diameter during the cardiac cycle. Aims: To establish the optimal CT reconstruction phase to demonstrate maximal cardiac venous area. Methods: 16 patients (11 male, 5 female; mean age 61.3 years) with complete data sets for 10 phases of the cardiac cycle were retrospectively analysed to establish a cross Figure 1. Mean CS Area. section of the coronary sinus (CS) and 159 interpretable images were available. The CS area was calculated from diameter measured in two orthogonal dimensions. Results: There was marked inter-individual variation in CS area (mean 81.5 mm 2 , S.D. 37.3 mm 2 ). There was a sig- nificant difference between maximal and minimal mean area (p = 0.0046) (Fig. 1). The interval between 30% and 50% of the cardiac cycle represented maximal CS area in 11 patients (69%). The maximal mean area occurred at 40% of the cardiac cycle (92.3 mm 2 , S.D. 41.6 mm 2 ). Conclusions: Maximal mean CS area occurs in the systolic phases of the cardiac cycle. Reconstruction at 40% may be preferable to typical diastolic (70%) reconstructions for venous imaging. doi:10.1016/j.hlc.2008.05.118 118 Increase in Left Atrial Volume in Mitral Regurgitation is mediated by an Increase in Passive Emptying with no Increase in Conduit or Active Emptying Volumes Jane Vidaic ∗ , Ee-May Chia, Anita Boyd, Liza Thomas, Dominic Y. Leung Liverpool Hospital, Sydney, NSW, Australia Background: Left atrial (LA) enlargement is well described in mitral regurgitation (MR) and is presumably due to the increased regurgitant volume. We sought to examine the phasic changes in LA volumes in varying grades of MR severity. Methods: Patients in sinus rhythm, with varying grades of MR, determined semi-quantitatively, were identified from the departmental database. Thirty patients in each of the categories of severe, moderate and mild MR were compared with ninety age-matched normal subjects. Max- imal/minimal left atrial volumes (LAV) and pre-p LAV were measured using Simpson’s bi-plane method. Pas- sive emptying, conduit, and active emptying volumes were calculated. Results: Maximal, minimal and pre-p LAV increased with increasing severity of MR that resulted in increased pas- sive LA emptying but no increase in passive emptying fraction. Conduit volume was reduced as a % of maximal LAV. There was no increase in active atrial emptying vol- ume with a resultant reduction in active emptying fraction. Subgroup analysis based on ischaemic versus valvular MR, demonstrated no significant difference in phasic atrial