Left and right ventricular strain–volume/area loops: an evaluation of intra-observer, inter-observer and test–retest reliability

Abstract INTRODUCTION Recent studies highlight that left (LV) and right ventricular (RV) strain–volume/area interactions, particularly systolic slope and coupling parameters, carry clinical and physiological relevance. This study evaluated the intra-observer, inter-observer and test–retest reliability of echocardiographic LV and RV strain–volume/area loops. METHODS 29 healthy adults underwent two transthoracic echocardiograms two hours apart after standardized preparation. One observer analysed the first scan twice (intra-observer reliability) and the second scan once (test–retest reliability). A second observer analysed the first scan once (inter-observer reliability). Observers were blinded and analysed data independently. Reliability was assessed for systolic (systolic slope (SS), peak strain (PS)) and coupling parameters (early (EarlyU) and late diastolic uncoupling (LateU)), using intraclass correlation coefficients (ICCs) and Bland–Altman analyses. RESULTS ICCs were generally higher for LV strain–volume than for RV strain–area loops. For LV, intra-/inter-observer and test–retest reliability was good-to-excellent for SS (ICCs: 0.84–0.92), moderate-to-good for PS and EarlyU (ICCs: 0.64–0.85 and 0.60–0.87, respectively), and poor-to-good for LateU (ICCs: 0.48–0.78). For RV, reliability was good for SS (ICCs: 0.78–0.89), poor-to-moderate for PS (ICCs: 0.19–0.59), moderate for EarlyU and LateU (ICCs: 0.53–0.68, and 0.60–0.73, respectively). Systematic bias was minimal. CONCLUSION Reliability was superior for LV-based parameters compared to RV. Both the LV and RV loops showed moderate-to-excellent reliability for SS and EarlyU, whilst reliability for PS and LateU varied from poor-to-good. These findings provide a methodological basis for future studies applying strain–volume and strain–area loops.