Lechner 2012.

Study characteristics
Methods	Study design: randomised controlled trial, parallel arm Setting: paediatric cardiac ICU, Children’s and Maternity Hospital, Linz, Austria Study start/end dates or study duration: between September 2007 and July 2009 Funding sources: Department of Anaesthesia and surgical intensive care of the AKH Linz (unpublished information) Declarations of interest: "The authors have not disclosed any potential conflicts of interest."
Participants	Sample size: 40 Patient age: milrinone group 63.9 ± 81.3 days, levosimendan group 78.4 ± 80.5 days Patient sex: 22 males, 18 females Diagnosis/severity: all with biventricular physiology, Aristotle complexity level 2‐4: ventricular septal defect, complete atrioventricular septal defect, total anomalous pulmonary venous connection, multiple ventricular septal defects, extended aortic coarctation, d‐transposition of the great arteries with or without ventricular septal defect Inclusion criteria: children younger than 1 yr of age scheduled for corrective open‐heart surgery
Interventions	Intervention 1: milrinone infusion at 0.5 μg/kg/min for 24 hours, starting at the time of weaning from CPB Intervention 2: levosimendan infusion at 0.1 μg/kg/min for 24 hours, starting at the time of weaning from CPB Co‐interventions: additional inotropic support at the discretion of the senior consultant in charge
Outcomes	Primary outcome(s): cardiac index assessed by transesophageal Doppler in the ventilated and sedated patient 2, 6, 9, 12, 18, 24, and 48 hours after initiation of the study drug Secondary outcome(s) Heart rate Systemic arterial pressure Left atrial pressure Mixed venous saturation Lactate concentrations Inotrope score Cerebral near infrared spectroscopy Echocardiographic fractional shortening Fluid requirement Urine output Duration of mechanical ventilation Length of stay in the intensive care unit Length of stay in hospital Inotrope score Follow‐up until hospital discharge, mortality follow‐up until 30 days
Notes	Intention‐to‐treat analysis: yes, plus per protocol analysis Trialists contacted: yes Unpublished information received: 30‐day mortality, incidence of MCS or heart transplant, funding, duration of mechanical ventilation, duration of ICU stay, hypokalaemia, inotrope score
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Computer‐generated random numbers
Allocation concealment (selection bias)	Low risk	Preparation and labelling of drugs by the local pharmacy on pharmacy premises
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Same infusion rates for both drugs, opaque black syringes and catheters. Record indicating the type of study drug was kept in a closed envelope in the patient’s chart to allow unblinding in case of emergency (never used throughout the study). All patients, parents, medical, and nursing staff members remained unaware of the study group assignments throughout the whole study period.
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Data were collected continuously before unblinding at the end of the study; statistical analysis by an external statistician. However, measurement of cardiac index by transoesophageal Doppler is not considered to be gold standard. Furthermore, it was not possible to obtain reliable standard deviations for inotropic score, as the information extracted from a figure (Figure 4 in this source) deviated from information provided by personal communication with the study author.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Study authors were contacted and asked for missing values. 3 dropouts not included in per‐protocol‐analysis (1 did not receive non‐milrinone study drug due to immediate reoperation).
Selective reporting (reporting bias)	Low risk	Study authors were contacted and asked for missing values.
Other bias	Low risk	No other bias suspected.