Sensitivity analyses
First, we performed a sensitivity analysis excluding patients from 2016, as only four patients received levosimendan this particular year (9% of total of patients eligible to our study in 2016), whereas the proportion of patients receiving levosimendan in 2017, 2018, and 2019 was quite stable (comprised between 26 and 38%), and to assess whether change in clinical practice may have affected the per-protocol estimate of effect of levosimendan on the primary outcome. Then, we used Fine and Gray’s competing risks model to estimate the subdistribution hazard ratio for ECMO weaning success (sHR) [