Objective: Although transthoracic echocardiography (TTE) is the most commonly used technique to evaluate left ventricular (LV) parameters, cardiac magnetic resonance (CMR) is considered to provide more accurate measurements. The aim of this study was to compare LV end-diastolic volume (LVEDV), end-systolic volume (LVESV) and ejection fraction (LVEF) assessed by TTE with those parameters obtained by CMR. Design and method: The study included 100 patients who underwent both TTE and CMR between 2021 and 2023. Echocardiographic images were analysed retrospectively by three independent investigators (R1, R2, R3). The following parameters were obtained using Simpson's biplane method: LVEDV, LVESV and LVEF. The echocardiographic values assessed by each investigator were then compared with reference values obtained by CMR. Statistical analyses were performed using repeated measures ANOVA with post hoc pairwise t-tests with Bonferroni correction. Results: The mean age of the study population was 47±18 years, 64% were male, and the median time between TTE and CMR was 27 days. The most common indication for CMR was evaluation of suspected cardiomyopathy (42%), followed by suspected acute myocarditis (16%). The repeated measures ANOVA test showed that there was a significant difference between measurements (R1/R2/R3/CMR) of LVEDV (R1=132.47 ml, R2=132.38 ml, R3=122.69 ml, CMR=183.72 ml, p=0.002) and LVESV (R1=59.27 ml, R2=65.7 ml, R3=60.97 ml, CMR=80.23 ml, p=0.002). Post hoc analysis showed that the differences were only due to the discrepancy between each echocardiographer and magnetic resonance imaging. There was no significant difference in LVEF between measurements (R1=44.44%, R2=47.56%, R3=46.96%, CMR=48.5%, p=0.243). Conclusions: Our study shows that echocardiographic values of LV volumes and EF have low interobserver variability. TTE tends to underestimate LV volumes compared to CMR, but LVEF is similar with both techniques.
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