Potential risks in using midodrine for persistent hypotension after cardiac surgery: a comparative cohort study

Persistent hypotension is a frequent complication after cardiac surgery with cardiopulmonary bypass (CPB). Midodrine, an orally administered alpha agonist, could potentially reduce intravenous vasopressor use and accelerate ICU discharge of otherwise stable patients. The main objective of this study was to explore the clinical impacts of administering midodrine in patients with persistent hypotension after CPB. Our hypothesis was that midodrine would safely accelerate ICU discharge and be associated with more days free from ICU at 30 days.

We performed a retrospective cohort study that included all consecutive patients having received midodrine while being on vasopressor support in the ICU within the first week after cardiac surgery with CPB, between January 2014 and January 2018 at the Montreal Heart Institute. A contemporary propensity score matched control group that included patients who presented similarly prolonged hypotension after cardiac surgery was formed. After matching, 74 pairs of patients (1:1) fulfilled inclusion criteria for the study and control groups. Midodrine use was associated with fewer days free from ICU (25.8 [23.7-27.1] vs 27.2 [25.9-28] days, p = 0.002), higher mortality (10 (13.5%) vs 1 (1.4%), p = 0.036) and longer ICU length of stay (99 [68-146] vs 68 [48-99] hours, p = 0.001). There was no difference in length of intravenous vasopressors (63 [40-87] vs 44 [26-66] hours, p = 0.052), rate of ICU readmission (6 (8.1%) vs 2 (2.7%), p = 0.092) and occurrence of severe kidney injury (11 (14.9%) vs 10 (13.5%) patients, p = 0.462) between groups.

The administration of midodrine for sustained hypotension after cardiac surgery with CPB was associated with fewer days free from ICU and higher mortality. Routine prescription of midodrine to hasten ICU discharge after cardiac surgery should be used with caution until further prospective studies are conducted.