Supplementary file 1. Detailed description of the cardiac magnetic resonance (CMR) method
The comprehensive CMR protocol included steady-state free precession end-expiratory breath- hold cines acquired in the vertical and horizontal long axis planes, with subsequent contiguous short-axis cines from the atrioventricular ring to the apex and acquisition of 2, 3, and 4-chamber and right ventricular (RV) outflow tract view cines, respectively. Slice thickness was 8 mm and a 2 mm-interslice gap was used in the short axis stack. Forty phases were acquired in each cine sequence and the average temporal resolution was 20 (2) ms. Typical sequence parameters were: repetition (TR, ms) to echo time (TE, ms) ratio, 2.7/1.12; flip angle (FA), 60o; matrix, 256*230; field of view (FoV), 350*263 mm; and acquisition time, 12 s. Through-plane breath- hold phase contrast sequences were acquired with a retrospectively ECG-triggered black-blood segmented gradient echo sequence at the level of the aortic and pulmonary valves (TR/TE, 4.54/2.5; FA, 20º; matrix/FoV, 192*108/360*270 mm; velocity encoding, 150 cm/s; and number of excitations = 1).
For T1 mapping imaging, end-expiratory single-shot, ECG-gated, motion-corrected, modified look-locker inversion recovery (MOLLI) sequences were acquired at end-diastole in the 4- chamber view and in three contiguous short axis slices with the following parameters: slice thickness, 8 mm; TR, 2.6 ms; TE, 1.06 ms; minimum TI, 100 ms with 80 ms-increments according to a 5(3)3 sampling scheme; matrix, 256*144; FoV, 350 x 263 mm; and FA, 35º.
T2 mapping was based on a gradient-recalled echo single shot fast low angle shot (FLASH) readout with multiple T2 preparations and recovery periods. ECG-gated, motion-corrected, end- expiratory sequences were acquired at end-diastole in the same views as T1 mapping with the following parameters: slice thickness, 8 mm; TR, 2.4 ms; TE, 1.28 ms; number of T2 preparations = 3 (0 ms, 35 ms, 55 ms); matrix size, 192*108; FOV, 360*288 mm; bandwidth, 1184 Hz/px; and flip angle, 70º. T2 mapping sequences were obtained only before contrast administration. Thereafter, a bolus of 0.15 mmol/kg gadoteric acid (Dotarem; Guerbet, France) was administered.
Coronary 3D TrueFISP was acquired at mid-diastole (TR/TE, 3.12/1.27; FA, 25°; matrix/FoV, 256*175/320*200 mm; spatial resolution, 1.5*1.25*1.5 mm3). Finally, T1-weighted ECG-gated breath-hold segmented inversion-recovery sequences (IR-FISP) with phase sensitive and magnitude reconstruction were acquired for LGE detection, starting 5-10 min after contrast administration in the same views as the cines (TR/TE, 2.88/1.19; matrix/FoV, 256*210/350x263 mm; inversion time, 300-400 ms; slice thickness, 8 mm; interslice gap, 2 mm). T1 mapping was repeated 15 min after contrast administration.
Images were analyzed with a specific software (Syngo, Siemens; Erlangen, Germany) by an experienced (>10 years) observer. End-diastole and end-systole were selected from the time- volume curve. Left (LV) and right ventricle (RV) endocardial and epicardial borders were manually delineated in all planes in end-diastole, while in end-systole only the respective LV/RV endocardial borders were delineated. LV papillary muscles were also delineated at end- diastole in all the planes in which they appeared.
LV mass was calculated from the end-diastolic frames. Papillary muscles were excluded when measuring ventricular volumes. End-diastole/systole volumes were calculated for both ventricles. Ejection fraction was calculated for each ventricle as (end-diastolic volume – end- systolic volume)/end-diastolic volume x 100.
First pass myocardial perfusion was assessed at rest. Presence of regional wall motion abnormalities and myocardial LGE were also investigated. Global native T1 and T2 values were obtained with the same software (SyngoVia, Siemens) at the level of the mid ventricular septum on the parametric map images. Segmental native T1 and T2 values were obtained for regions of interest (typically of 1cm2) manually drawn in each of the 16 myocardial segments.
