Effect of prone versus supine positioning on left ventricular ejection fraction (LVEF) and heart rate using ECG gated Tl-201 myocardial perfusion scans and gated cardiac blood pool scans.

Introduction: There is limited data on the effect of posture on LVEF. The study aim was to determine any difference in LVEF using gated cardiac blood pool scanning (GCBPS) and Tl-201 gated myocardial perfusion scanning (MPS) in prone or supine positions.

Method: In 50 patients undergoing evaluation for varying heart conditions, automated LVEF, end diastolic volume (EDV), end systolic volume (ESV) measurements were obtained at rest during gated MPS on Discovery NM 530c (GE Healthcare). In another 50 patients, semi-automated LVEF measurements were obtained using GCBPS on dual-headed gamma cameras. Average heart rate (HR) was recorded. Differences between prone and supine LVEF, HR, EDV and ESV were compared using paired two-tailed t-tests (P < 0.05 considered significant). Pearson's correlation, difference plots, mean, standard deviation and 95% confidence interval of the differences were also derived to analyse LVEF results.

Results: Using GCPBS or MPS, no significant difference in LVEF or LV volumes (from gated MPS) was demonstrated between postures. Increased HR was noted in prone positioning.

Conclusion: Posture did not affect measured LVEF or LV volumes. However HR was higher on prone imaging.