Milrinone is often used to reduce the risk of low cardiac output syndrome, the investigators noted in a report published online September 7 in the American Journal of Cardiology.
However, emerging evidence suggests that in adults undergoing cardiac surgery, milrinone may be associated with postoperative arrhythmias.
To investigate that possibility in children, Dr. Andrew H. Smith and colleagues at the Monroe Carell Jr. Children’s Hospital and Vanderbilt University in Nashville enrolled 603 patients undergoing 724 congenital heart surgeries at their institution in an ongoing, prospective observational study. The median age of the subjects was 5.5 months.
At the discretion of the anesthesiologist and surgeon, milrinone was administered at the end of cardiopulmonary bypass and followed by continuous infusion. The drug was often used in patients who did not undergo cardiopulmonary bypass. In fact, the authors found, patients received milrinone in more than 70% of the operations, often in combination with other inotropes, including dopamine and epinephrine.
At least one arrhythmia was documented in 50% of operative procedures, and 65% of these were clinically significant and warranted therapeutic intervention, according to the report. Most often these were tachyarrhythmias, and most occurred on day 0.
On univariate analysis, the risk of clinically significant tachyarrhythmias was associated with patient characteristics such as age and weight, operative factors such as the use and duration of cardiopulmonary bypass, and with pharmacologic factors: administration of dopamine (odds ratio 1.7), epinephrine (OR 2.7) and milrinone (OR 7.1).
On multivariate analysis, milrinone administration on admission to the cardiac intensive care unit remained independently associated with the development of a tachyarrhythmia prompting intervention (OR 2.8; p=0.007).
The authors caution, “The association we have described between milrinone exposure after congenital heart surgery and postoperative tachyarrhythmias does not necessarily establish a causal relation.”
They note that milrinone use was “the rule and not the exception” in children having surgery at their hospital to repair heart defects. “As such, this makes a controlled comparison of milrinone use and any association with tachyarrhythmias among patients after specific operative procedures particularly difficult,” they wrote.
That being the case, they suggest, “Additional prospective, randomized, controlled investigations are warranted to confirm an independent contributory association between an agent commonly used after congenital heart surgery and this clinically relevant postoperative morbidity.”
Source: Reuters Health