Decreased Risk of Severe Delayed Cerebral Ischemia after Aneurysmal Subarachnoid Hemorrhage in the Era of Intravenous Milrinone

Background The efficacy and optimal timing of intravenous (IV) milrinone for cerebral vasospasm (CVS) has not been definitively established. The purpose of this study was to investigate the effect of IV milrinone on delayed cerebral ischemia (DCI) when angiographic CVS was detected. Methods An institutional database of aSAH was queried for moderate or severe angiographic CVS from 2016 to 2024. Patients were classified into those who received IV milrinone and those who did not. After propensity score matching, study outcomes included DCI-related infarct, additional angioplasty, recurrent CVS requiring ≥3 subsequent endovascular treatments, and mortality. Effect sizes were adjusted in multiple regression and subgroup analyses. Results Among 619 patients with aSAH, 37% had moderate or severe angiographic CVS (n=230). IV milrinone was administered in 27% of patients (n=63/230). Of these patients, 78% were symptomatic, and 30% had initially severe CVS requiring angioplasty. Compared to baseline-matched patients, those who received IV milrinone had a lower incidence of subsequent DCI infarct (6.3% vs. 24%, P =.006). In multiple regression, IV milrinone was associated with a significantly decreased incidence of DCI infarct (aOR 0.08, 95%CI 0.02-0.42). DCI-related mortality was decreased in Hunt-Hess 4-5 patients on milrinone (4% vs. 32%, P =.03). Patients with severe CVS who received IV milrinone required less additional angioplasty than those who did not (5.3% vs. 37.5%, P =.03). Conclusion This study provides evidence that there is a lower risk of cerebral infarcts and DCI refractory to endovascular treatment in the era of IV milrinone.