Evaluation of left ventricular function using acoustic quantification: Inter-institutional variability study

Acoustic quantification (AQ) is a validated technique for the evaluation of left ventricular performance. Multiple studies have determined its inter-observer variability within one Institution. However, there are subtleties in the technique that vary from institution to institution. The variability between institutions when studying the same subjects has not been determined. Methods. As part of a multicenter study aimed at obtaining normal values of acoustic quantification (NOVAQ), six centers performed AQ examinations on the same five subjects (age 23±5 yrs) in a single setting, using identical equipment (SONOS-2500, HP). Left ventricular area and volume waveforms were acquired from the parasternal short axis and apical four-chamber views, respectively, and videotaped continuously for 45 seconds. Videotapes were reviewed off-line, and values of the following parameters were obtained from three stable, non-consecutive beats and averaged: end-diastolic (ED) and end-systolic (ES) volume or area, ejection fraction (EF) or fractional area change (FAC), peak rate of emptying and filling (PER, PFR). In each subject, the absolute difference in percent of the mean between values obtained by songraphers from different institutions was computed for each variable. Results: ED ES EF/FAC PER PFR % absolute difference (area) 8.4% 13% 6.7% 10% 8.2% % absolute difference (volume) 13% 19% 9.7% 9.3% 9.2% Conclusion: LV performance indices (EF, FAC, PER, PFR) were reproducible within a narrow range of 10%. The interinstitutional variability in volume measurements was slightly higher. This may reflect the inter-institutional differences in setting gains and selecting imaging plane, which affect volume and area more than EF and FAC measurements.