Targeting higher intraoperative blood pressures does not reduce postoperative complications in at-risk patients undergoing noncardiac surgery, a new Swiss single-center randomized controlled trial (RCT) concluded.
However, it will take results from the “much larger” ongoing POISE-3 and GUARDIAN trials to draw conclusive findings, editorialists cautioned.
Results from the current study were published Monday online ahead of the Nov. 2 issue of the Journal of the American College of Cardiology, led by Patrick M. Wanner, MD – of Cantonal Hospital St. Gallen, Switzerland, at the time of the study, but now affiliated with University Hospital Basel.
Low blood pressure is strongly associated with postoperative major adverse cardiovascular events (MACE) and all-cause morbidity, but whether the opposite could be true – namely whether higher intraoperative blood pressures could mean better outcomes after surgery –had remained unclear.
The current study was, therefore, set up to determine whether targeting higher intraoperative mean arterial blood pressures (MAPs) could lower postoperative MACE rates at 30 days and 1 year in patients at cardiovascular risk following major noncardiac surgery.
The 458 adult patients over 45 years of age (intention-to-treat population: 451) were enrolled at the Cantonal Hospital St. Gallen, Switzerland, from March 7, 2016 to April 17, 2019, with last follow-up on April 17, 2020. They were randomized 1:1 in the preoperative anesthesia clinic to a European Society of Cardiology (ESC)/ European Society of Anaesthesiology (ESA)-recommended intraoperative MAP target of ≥60 mmHg (the control group) or a higher target of ≥75 mmHg.
These patients’ cardiovascular risk was defined as meeting at least one of six key criteria: history of coronary artery disease, peripheral artery disease, stroke or congestive heart failure; undergoing major vascular surgery (excluding arteriovenous shunt, vein stripping procedures, and carotid endarterectomies); or fulfillment of any three of the seven Lee criteria in the revised cardiac risk index.
The primary outcome was acute myocardial injury on postoperative days 0-3 and/or 30-day MACE/acute kidney injury (AKI) (acute coronary syndrome, congestive heart failure, coronary revascularization, stroke, AKI, and all-cause mortality).
Notably, hypotension time – during which MAP was below 65 mmHg – was 60% shorter for the target high blood pressure group, with a 9-minute median (interquartile range [IQR]: 3 to 24 minutes) compared to a 23-minute median (IQR: 8 to 49 minutes) for the group within ESC/ESA guidelines (P < 0.001).
Nevertheless, the primary outcome still occurred for 108 patients (48%) with higher target MAP ≥75 mmHg and 118 (52%) of the control group (risk difference -4.2.%; 95% confidence interval [CI]: -13% to +5%), with AKI as the primary contributor (44%).
Acute myocardial injury occurred in 33 (15%) of the higher target MAP group compared to 43 (19%) of the control subjects (risk difference: -4.4%; 95% CI: -11% to +2.5%), and MACE/AKI in 101 (45%) versus 105 (46%), with AKI present in 96 (43%) vs. 104 (46%) (risk difference: -3.4%; 95% CI: -13% to +5.8%), respectively.
The secondary outcome of 1-year MACE was seen in 17% of those with MAP ≥75 mmHg versus 15% of control (risk difference +2.7; 95% CI: -4% to +9.5%).
“These findings do not support universally targeting higher intraoperative blood pressures to reduce postoperative complications,” the authors concluded.
“Further studies examining the interplay of intraoperative hypotension, perioperative hemodynamic intervention, and postoperative outcomes with a focus on individualization are needed,” they added.
“Only once the mechanisms underlying perioperative cardiovascular complications are better understood will we be able to design meaningful interventions that could one day benefit our patients.”
However, editorialists stressed that despite the primary outcome of the trial not differing by statistically significant or clinically meaningful amounts in the current treatment groups, “clinicians should not interpret the results as ‘ruling out’ an important effect of hypotension on serious complications.”
Such a conclusion would require a much larger trial, said Daniel I. Sessler, MD, of Cleveland Clinic, and Timothy G. Short, MD, of The University of Auckland and Auckland District Health Board, New Zealand – namely the ongoing studies POISE-3 (PeriOperative ISchemic Evaluation-3 Trial) in 9,500 patients, and GUARDIAN (tight perioperative blood pressure management to reduce serious cardiovascular, renal, and cognitive complications) in 6,254 patients.
POISE-3 has just completed recruitment, while GUARDIAN has just started, they noted.
“In coming years, we should thus have robust information about the extent to which the association between hypotension and major organ injury is causal, and at what thresholds. In the meantime, clinicians would be prudent to avoid hypotension when practical.”
Wanner PM, Wulff DU, Djurdjevic M, et al. Targeting Higher Intraoperative Blood Pressures Does Not Reduce Adverse Cardiovascular Events Following Noncardiac Surgery. J Am Coll Cardiol 2021;78:1753-1764.
Sessler DI, Short TG. Intraoperative Hypotension and Complications. J Am Coll Cardiol 2021;78:1765-1767.
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