Abstract 3020: Established MRI Methods for Ejection Fraction and Myocardial Mass Quantification Produce Significantly Different Results Based on Trabecular and Papillary Volumes: Effects on Clinical Standards in Heart Failure
Background Left ventricular mass (LVM) and ejection fraction (EF) are of diagnostic and therapeutic importance in heart failure (CHF). Cardiac MRI (CMR) has been proposed as a standard for these indices. Prior CMR studies have variably included papillary muscles and trabeculae in either intracavitary or myocardial volumes. Effects of this methodological difference in CHF patients (pts) are unknown and may impact clinical management.
Methods We studied consecutive pts undergoing CMR (1.5T) with known CHF (echo or MUGA EF< 40%). Steady state free precession short axis images were acquired contiguously throughout the left ventricle (LV). LV volumes were quantitatively determined according to two established methods: Method 1 included papillary muscles and all trabeculae in cavity volume, method 2 included these in myocardial volume. Both methods were used for each pt with tracings superimposed to isolate papillary/trabecular volume and insure consistency of other endocardial contours. Readers applied methods in random order blinded to clinical findings and quantitative results of the other method.
Results 50 patients underwent CMR (61 ± 17 yrs, 76% men, 76% HTN, 68% coronary disease). LVM differed substantially by method (p < 0.0001) with mean relative difference of 20% (table⇓). LV end diastolic and end systolic volumes also differed (p < 0.0001) with mean EF difference of 3 points and absolute differences of ≥5 points in 16% of pts. LVM and EF differed in pts with or without CAD. Methodology of LV volume measurement affected proportions of pts meeting established criteria for LV hypertrophy (26% vs 56%, p<0.0001) and ICD implantation (EF < 30% in 64% vs 48%, p < 0.008).
Conclusions LVM and EF differ significantly between currently used CMR methods. Alternative inclusion of papillary/trabecular volumes in either cavitary or myocardial volumes produces significant differences in clinical and therapeutic indices that may affect management of CHF patients.