Data was partially missing for 275/1604 (17%) of participants. Between those with missing and no missing data, the groups were similar for all co-variates other than BMI (25.8 kg/m2 vs. 26.8 kg/m2, p = 0.003) and systolic blood pressure (133 mmHg vs. 137 mmHg, p = 0.009) which were higher in those with missing data. After multiple imputation of missing values, the effect sizes are similar to those from complete case analysis with the same CMR parameters realising significance. The complete case analysis detailed in the main manuscript provides more conservative results.