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553
VENTRICULAR GEOMETRY AND EJECTION FRACTION: AN ANALYSIS FROM THE OCCLUDED ARTERY TRIAL (OAT)
K Ramanathan, CE Buller, RG Carere, EA Cohen, WJ Canter, AY Fung, J Webb, J Mancini, JR Ross, DJ Atchison, S Forman, V Dzavik
New York, New York; Vancouver, British Columbia; Toronto, Ontario
BACKGROUND: Myocardial infarction (MI) leading to systolic left ventricular (LV) dysfunction may result in ventricular remodelling (VR). Morphologically, VR following MI consists of increases in LV volume (LVV) and loss of ellipsoidal LV shape, thereby increasing regional wall tension and stress. Such changes usually impair LV ejection fraction (EF). The degree of interdependence of LVEF and VR is unclear. Contrast left ventricular angiograms (LVA) from the Occluded Artery Trial (OAT) were used to examine this question.
METHODS: OAT patients manifest occluded (TIMI grade 0,1) infarct-related arteries (IRA) 3-28 days post-MI. Core laboratory measurements of LVEF (area/length method) and dimensions were undertaken in 999 patients with analyzable LVA at time of study entry. LV geometry was derived from a single plane right anterior oblique (30°) LVA at end systole (Sys) and end diastole (Dia). Sphericity indices were calculated as the ratio of the measured LVV and the volume of an imaginary sphere with the diameter equal to the LV long axis.
RESULTS: The IRA was identified as LAD in 335, LCX in 159, and RCA in 505 patients. LVEF was lower if the IRA was LAD (42%±12) vs LCX or RCA (52%±10), p<0.0001. Both Sys and Dia index correlated modestly with EF (R2=0.15 and 0.05 respectively; p<0.0001 for both). Correlation between Sys and Dia sphericity index was R=0.72. The correlation between LVEF and Sys index was largest when the IRA was LAD (R2=0.37; p<0.0001). The relationship between LVEF and Sys index was similar regardless of time from MI to LVA (
CONCLUSION: In patients with MI and LV dysfunction a correlation exists between LVEF and measures of VR with a single plane LVA. Shape indexes may provide insights that complement or refine the known, prognostic power of LVEF in occluded artery patients. The ongoing OAT provides an opportunity to resolve whether long-term clinical outcome is related to VR as well as LVEF.
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