(152) Timing of Renin-Angiotensin-Aldosterone Inhibitor Administration and Vasoplegia Post-Cardiac Surgery

Introduction: Current literature suggests an association between preoperative continuation of renin-angiotensin-aldosterone system inhibitors (RAASi) prior to cardiac surgery and an increased risk of vasoplegia. Evidence is lacking regarding the optimal timing of preoperative RAASi discontinuation. The aim of this study was to determine the incidence of vasoplegia post cardiac surgery based upon the timing of preoperative administration of RAASi.

Methods: Retrospective chart review was conducted on 107 patients undergoing non-emergent cardiac surgery. Outcomes were compared based on RAASi administration less than 24 hours ( < 24h group) versus greater than 24 hours (>24h group) before surgery. The primary outcome of vasoplegia was defined by hemodynamic criteria including cardiac index (CI) >2.1 L/kg/m2, systemic vascular resistance (SVR) < 800 dynes/cm5, and a mean arterial pressure < 65 mmHg or systolic blood pressure < 90 mmHg. Patients who received inotropes were excluded.

Results: A total of 107 patients were included, 34 in the < 24h group and 73 in >24h group. Incidence of vasoplegia was similar between groups at 38.2% versus 32.9% respectively (p=0.587), and there was a trend in time to vasoplegia at 8 hours post-surgery evident in the < 24 hours group. Significantly more patients underwent an isolated CABG in the < 24h group at 94.1% versus 78.1% (P < 0.034). Cardiopulmonary bypass times (98.6 ± 38.8 min vs 93.6 ± 35.5 min, p=0.512) and aortic cross clamp times (62.6 ± 26.5 min vs 62.2 ± 29.1 min, p=0.946) were similar between groups. There were higher rates of vasopressor requirements in the < 24h group, though not statistically significant (91.2% vs 61.8%, p=0.225). There were no significant differences in 30-day mortality or morbidity between groups, but the < 24h group trended toward a significantly longer hospital length of stay (13.0 ± 7.6 days vs 8 ± 8.1 days, p=0.0003).

Conclusions: RAASi administration less than 24 hours versus greater than 24 hours before non-emergent cardiac surgery did not result in a significantly higher incidence of vasoplegia. The less than 24 hours group had a longer hospital length of stay and trended toward higher rates of vasopressor requirements post-operatively.