Milrinone has been used in some children to reduce the risk of low cardiac output syndrome following congenital heart surgery. Data from adults have suggested a link between milrinone use and postoperative arrhythmias Researchers hypothesised that milrinone was also an independent risk factor for clinically significant tachyarrhythmias after congenital heart surgery.

This analysis involved 603 subjects enrolled in the ongoing prospective, observational PACS (Postoperative Arrhythmia in Congenital Heart Surgery) study, who were undergoing congenital heart surgery and were subsequently admitted to the paediatric cardiac intensive care unit (CICU) from July 2007 to September 2010.

The following findings were reported:

• The overall arrhythmia incidence was 50%, most commonly monomorphic ventricular tachycardia (n = 85, 12%), junctional ectopic tachycardia (n = 69, 10%), accelerated junctional rhythm (n = 58, 8%), and atrial tachyarrhythmias (including atrial fibrillation, atrial flutter, and ectopic or chaotic atrial tachycardia, n = 58.8%).

• Independent of age <1 month, the use of cardiopulmonary bypass, the duration of cardiopulmonary bypass, Risk Adjusted classification for Congenital Heart Surgery, version 1, score >3, and the use of adrenaline or dopamine, milrinone use on admission to the CICU remained independently associated with an increase in the odds of postoperative tachyarrhythmia resulting in an intervention (odds ratio 2.8, 95% CI, 1.3 to 6.0, p = 0.007).

The researchers conclude from these findings that “milrinone use is an independent risk factor for clinically significant tachyarrhythmias in the early postoperative period after congenital heart surgery.” They discuss the limitations of their study and acknowledge that the association described does not necessarily establish a causal relationship. They call for additional prospective, RCTs to confirm “an independent contributory association between an agent commonly used after congenital heart surgery and this clinically relevant postoperative morbidity.”