Levosimendan, a drug used to prevent heart failure during heart surgery, was shown to not reduce adverse outcomes in patients at a high risk for low cardiac output syndrome in a new study debuted at the American College of Cardiology’s 66th Annual Scientific Sessions.

The drug, a calcium inotrope, is not approved in the U.S. yet, but is commonly used in many other countries. This trial is the first to examine the use of levosimendan before and after cardiac surgery and if it prevents low cardiac output syndrome and other adverse outcomes.

The trial included more than 880 patients at 70 centers throughout North America. All participants underwent surgery in which they put on a heart-lung machine and had a left ventricular ejection fraction less than 35 percent.

Patients were randomized to receive levosimendan or placebo starting just before and for the 24 hours after. Results showed that low cardiac output syndrome was less frequent with levosimendan. It occurred in only 18.2 percent of patients who took the drug and in 25.7 percent of patients on the placebo

“Based on the other promising data that exist for levosimendan in this setting, these results surprised us,” said John H. Alexander, MD, the lead author on the study and a cardiologist at Duke Clinical Research Institute, in a statement. “Given levosimendan’s lack of effect on clinically important outcomes in our study, it probably doesn’t make sense to use it routinely prophylactically in patients undergoing heart surgery. Other ongoing trials may help to further inform how levosimendan should be used in patients undergoing cardiac surgery.”