Abstract
Background: Despite steady improvements in cardiac surgery-related outcomes, our understanding of the physiologic mechanisms leading to perioperative mortality remains incomplete. Intraoperative hypotension is an important risk factor for mortality after noncardiac surgery but remains relatively unexplored in the context of cardiac surgery. We examined whether the association between intraoperative hypotension and in-hospital mortality varied by patient and procedure characteristics, as defined by the validated Cardiac Anesthesia Risk Evaluation (CARE) mortality risk score. Methods: We conducted a retrospective cohort study of consecutive adult patients who underwent cardiac surgery requiring cardiopulmonary bypass (CPB) from November 2009–March 2015. Those who underwent off-pump, thoracic aorta, transplant and ventricular assist device procedures were excluded. The primary outcome was in-hospital mortality. Hypotension was categorized by mean arterial pressure (MAP) of <55 and between 55–64 mmHg before, during and after CPB. The relationship between hypotension and death was modeled using multivariable logistic regression in the intermediate and high-risk groups. Results: Among 6627 included patients, 131 (2%) died in-hospital. In-hospital mortality in patients with CARE scores of 1, 2, 3, 4 and 5 was 0 (0%), 7 (0.3%), 35 (1.3%), 41 (4.6%) and 48 (13.6%), respectively. In the intermediate-risk group (CARE = 3–4), MAP < 65 mmHg post-CPB was associated with increased odds of death in a dose-dependent fashion (adjusted OR 1.30, 95% CI 1.13–1.49, per 10 min exposure to MAP < 55 mmHg, p = 0.002; adjusted OR 1.18 [1.07–1.30] per 10 min exposure to MAP 55–64 mmHg, p = 0.001). We did not observe an association between hypotension and mortality in the high-risk group (CARE = 5). Conclusions: Post-CPB hypotension is a potentially modifiable risk factor for mortality in intermediate-risk patients. Our findings provide impetus for clinical trials to determine if hemodynamic goal-directed therapies could improve survival in these patients.
Highlights
Intraoperative hypotension is an established risk factor for in-hospital and one-year mortality after noncardiac procedures, and cardiovascular and renal-related complications after both cardiac and noncardiac surgery [1,2,3,4,5,6]
A recent multicenter study of major noncardiac surgery suggests that the association between intraoperative hypotension and postoperative risk of acute kidney injury (AKI) varies by baseline patient and procedure risk, such that AKI was not associated with hypotension in low-risk patients, whereas an association was found with severe hypotension in the medium-risk group, and with milder degrees of hypotension in the highest-risk group [7,8]
We examined whether the association between intraoperative hypotension and in-hospital mortality varied across different baseline risk profiles, as defined by individual patient and procedure characteristics
Summary
Intraoperative hypotension is an established risk factor for in-hospital and one-year mortality after noncardiac procedures, and cardiovascular and renal-related complications after both cardiac and noncardiac surgery [1,2,3,4,5,6]. Studies in patients undergoing major cardiac surgery reported an increase in the risk of 30-day mortality in low-risk patients who exhibited perioperative systolic blood pressure variation (which included hypotensive episodes) compared to high-risk patients [9]. Despite this evidence, the interaction between hypotension and baseline patient disease burden has not been clearly defined in cardiac surgery patients. We examined whether the association between intraoperative hypotension and in-hospital mortality varied across different baseline risk profiles, as defined by individual patient and procedure characteristics. Our findings provide impetus for clinical trials to determine if hemodynamic goal-directed therapies could improve survival in these patients
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