Cardiovascular magnetic resonance (CMR) is a precise tool for the assessment of cardiac anatomy, function, and tissue composition. However, studies providing CMR reference values in adolescence are scarce. We aim to provide sex-specific CMR reference values for biventricular and atrial dimensions and function and myocardial relaxation times in this population. Adolescents aged 15–18 years with no known cardiovascular disease underwent a non-contrast 3-T CMR scan between March 2021 and October 2021. The imaging protocol included a cine steady-state free-precession sequence for the analysis of chamber size and function, as well as T2-GraSE and native MOLLI T1-mapping for the characterization of myocardial tissue. CMR scans were performed in 123 adolescents (mean age 16 ± 0.5 years, 52% girls). Mean left and right ventricular end-diastolic indexed volumes were higher in boys than in girls (91.7 ± 11.6 vs 78.1 ± 8.3 ml/m², p < 0.001; and 101.3 ± 14.1 vs 84.1 ± 10.5 ml/m², p < 0.001), as was the indexed left ventricular mass (48.5 ± 9.6 vs 36.6 ± 6.0 g/m², p < 0.001). Left ventricular ejection fraction showed no significant difference by sex (62.2 ± 4.1 vs 62.8 ± 4.2%, p = 0.412), whereas right ventricular ejection fraction trended slightly lower in boys (55.4 ± 4.7 vs. 56.8 ± 4.4%, p = 0.085). Indexed atrial size and function parameters did not differ significantly between sexes. Global myocardial native T1 relaxation time was lower in boys than in girls (1215 ± 23 vs 1252 ± 28 ms, p < 0.001), whereas global myocardial T2 relaxation time did not differ by sex (44.4 ± 2.0 vs 44.1 ± 2.4 ms, p = 0.384). Sex-stratified comprehensive percentile tables are provided for most relevant cardiac parameters. This cross-sectional study provides overall and sex-stratified CMR reference values for cardiac dimensions and function, and myocardial tissue properties, in adolescents. This information is useful for clinical practice and may help in the differential diagnosis of cardiac diseases, such as cardiomyopathies and myocarditis, in this population. 10.13039/501100004587 Instituto de Salud Carlos III (PI19/01704).

Background: Coronary subclavian steal syndrome (CSSS) is an uncommon complication observed in patients after coronary artery bypass surgery with left internal mammary artery (LIMA) grafts. It is defined as coronary ischaemia due to reversal flow from the LIMA to the left subclavian artery (SA) when a proximal left SA stenosis is present. In practice, the entire clinical spectrum of ischaemic heart disease, ranging from asymptomatic patients to acute myocardial infarction, may be encountered. Case summary: Three cases of CSSS recently detected at our hospital are being described. Two patients presented with an acute coronary syndrome, so diagnosis was suspected based on coronary angiography findings, as retrograde blood flow from LIMA to the distal SA was present. Myocardial ischaemia was documented by myocardial perfusion scintigraphy in one case. The third patient was asymptomatic and CSSS was suspected during physical examination and confirmed by computed tomography (CT). Endovascular intervention with balloon-expandable stent implantation of the stenotic SA was performed by vascular surgeons in all patients. No periprocedural complications occurred, and complete resolution of symptoms was achieved. Discussion: In CSSS, subclavian angiography is the standard diagnostic test. However, other diagnostic techniques may be valuable to better clarify this challenging diagnosis. In the herein small series, the usefulness of a multimodality imaging approach including Doppler ultrasound, myocardial perfusion scintigraphy, and CT is well demonstrated. Furthermore, this study endorses the safety and utility of endovascular treatment in different clinical scenarios, including asymptomatic patients.