Assessing the role of supine and prone positioning on left ventricular volumes, ejection fraction, and heart rate using ECG-gated [99mTc]Tc-MIBI myocardial perfusion scan

Introduction: Gated myocardial perfusion SPECT (GMPS) using [99mTc]Tc-MIBI allows the cardiac function assessment in addition to the myocardial perfusion. Although the prone position has been suggested as a complementary protocol in GMPS, there is no firm recommendation on its effect on function and physiologic conditions of cardiac. We aimed to evaluate the impact of supine and prone positions on left ventricular end-systolic volume (ESV), end-diastolic volume (EDV), ejection fraction (LVEF), and heart rate (HR). Methods: Ninety-six patients with no history of ischemic heart disease or cardiomyopathy participated in this study. Using GMPS at both supine and prone positions, volume-based cardiac function was evaluated. ESV, EDV, LVEF, and HR were obtained and compared between supine and prone positions. A two-tailed p-value of < 0.05 was considered significant. Results: Using GMPS, no significant difference in ESV, EDV, LVEF, and HR was demonstrated between the two positions (p-value>0.05). The mean LVEF results derived from the supine versus prone position were 67.22% (42-93%) vs. 64.22% (41-89%) (p-value=0.71). ESV results were 23.28 vs. 27.23 (p-value=0.39). EDV results were 65.78 vs. 70.33 (p-value=0.27). Furthermore, HR results were close to each other in supine 72.22 (45-106) and prone 74.99 (47-110) positions (p-value=0.68). Conclusion: It seems that prone positioning causes no considerable change in cardiac volumes. As a result, the prone position can be an acceptable alternative to the supine position when volume-based assessments are considered.