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Introduction Cardiovascular magnetic resonance (CMR) is established as the reference standard for cardiac volumetric assessment. Despite its accuracy and robustness, steady-state free precession (SSFP) cine imaging may prove challenging in patients with arrhythmia or in those who cannot perform repeated breath holds. An alternative method is a free-breathing real-time cine sequence. We have previously demonstrated good-excellent agreement of this technique in 202 clinical patients compared to standard SSFP in the same sitting. 1 However, the repeatability of real-time cine between studies is unknown. This is pertinent for assessing serial changes in cardiac function following therapeutic interventions such as drug/device therapy or revascularisation. In this study, we investigated the repeatability of real-time cine imaging in patients with suspected coronary artery disease (CAD).Methods In this single-centre, prospective study, consecutive adults with suspected CAD underwent two research 3-Tesla CMR scans on different days. Subjects underwent a free-breathing, multi-slice, electrocardiogram-triggered, retrogated, real-time cine sequence that acquired an entire left ventricular (LV) short-axis stack in approximately 1 minute. Short-axis image dataset pairs were separated and blindly analysed using cvi42 software (Circle Cardiovascular Imaging, Calgary, Canada). Volumetric assessment utilised the cvi42 automated contouring tool with visual inspection and adjustments when necessary. LV end-diastolic volume (EDV), end-systolic volume (ESV), ejection fraction (EF) and LV mass (LVM) were calculated. Paired sample t-tests were used to compare within group differences, and agreement, using intraclass correlation coefficient (ICC) [95% confidence interval] and Bland-Altman plots. Interobserver variability was assessed by an external observer analysing a subset of 15 scans, blinded to previous results.Results Fifty patients (mean age 67 ± 10 years, 40% female) were studied. Baseline characteristics are presented in table 1. The median interval between CMR exams was 2 days [Q1-Q3, 1–3]. Baseline heart rate and systolic blood pressure were similar between studies (p=0.502 and p=0.772 respectively). There were no significant differences in EDV (151.2±31.6ml vs. 154.7±33.4ml, p=0.193), ESV (60.4±22.3ml vs. 62.8±23.2ml, p=0.083), EF (60.7±8.9% vs. 60.1±8.1%, p=0.304) or LVM (97.7±28.4g vs. 95.9±27.9g, p=0.370) between exams. All LV volumetric measurements exhibited good agreement between both real-time scans (EDV: ICC 0.83 [0.71–0.90], ESV: 0.91 [0.84–0.95], EF: 0.87 [0.78–0.92] and LVM: 0.87 [0.79–0.93]) with good interobserver agreement (table 2, figure 1A and B).Abstract 6-020 Table 1Baseline characteristics Patients with suspected CAD, n=50 Demographics Age, years 67 ± 10 Female 20 (40%) Body mass index, kg/m2 29.6 ± 4.2 Risk factors Ever smoked tobacco 24 (48%) Type II diabetes 8 (16%) Hypertension 33 (66%) Hypercholesterolemia 27 (54%) Family history of premature CAD 22 (44%) Abstract 6-020 Table 2Comparison of LV volumetric measurements and ICC between real-time scans Mean Difference [95% CI] P-value ICC [95% CI] Interobserver variability ICC [95% CI] EDV, ml -3.6 [-9.0–1.9] 0.193 0.83 [0.71–0.90] 0.85 [0.60–0.95] ESV, ml -2.4 [-5.2–0.3] 0.083 0.91 [0.84–0.95] 0.93 [0.82–0.98] EF, % 0.6 [-0.6–1.9] 0.304 0.87 [0.78–0.92] 0.91 [0.75–0.97] LVM, g 1.8 [-2.2–5.8] 0.370 0.87 [0.79–0.93] 0.86 [0.63–0.95] Abstract 6-020 Figure 1(A) Bland-altman plots illustrating agreement of EDV and ESV between real-time scans; (B) Bland-Altman plots illustrating agreement of EF and LVM between real-time scansConclusions In patients with suspected CAD, real-time cine imaging demonstrates good repeatability for LV volumetric assessment. This accelerated imaging technique shows promise for routine integration within clinical practice, improving the tolerability and efficiency of CMR, whilst providing an accurate serial measure of cardiac function.Reference El Shibly M, Parke K, England R, Budgeon CA, Grafton-Clarke C, Xue H, et al. Comparison of standard breath-hold ssfp cardiac MRI with free-breathing real-time cine imaging among patients with known or suspected cardiac disease. Journal of Cardiovascular Magnetic Resonance. 2024;26.