Renin-angiotensin blockade is associated with increased mortality after vascular surgery.
OBJECTIVE
The outcome of patients with preoperative renin-angiotensin system (RAS) blockade, achieved either by angiotensin converting enzyme inhibitors or angiotensin receptor blocking agents, was assessed using 30-day mortality as a primary end point.


METHODS
An observational cohort study of 883 consecutive patients undergoing elective open abdominal aortic aneurysm repair (AAA) was undertaken and analyzed using a propensity score matched study. The data collected included medical history, anesthetic techniques, and postoperative outcomes. Logistic regression analysis identified predictors of RAS blockade: hypertension, stroke, congestive heart failure, diabetes, and heart disease. A propensity score for RAS blockade was calculated for each subject using several factors: age, sex, serum creatinine, hypertension, heart disease, congestive heart failure, stroke, diabetes, and exposure to cardiovascular medications. Subjects and controls were matched using the calculated propensity score.


RESULTS
The overall 30-day mortality rate was 3.5% (31/883 patients). The crude mortality rate in RAS blocked patients was 5.8% (21/359) vs 1.9% (10/524) in unexposed patients (odds ratio 3.2, with 95% confidence intervals [CI(95)] 1.5-6.7; P < 0.001). Analysis of 261 propensity score matched pairs showed a 30-day mortality rate of 6.1% (16/261) in the RAS blocked group vs 1.5% (4/261) in unblocked patients (P = 0.008). The estimated odds ratio for 30-day mortality associated with RAS blockade was 5.0 (CI(95) 1.4-27).


CONCLUSIONS
Examination of 883 cases of AAA repair showed increased mortality associated with preoperative RAS blockade. A better understanding of perioperative pharmacology and physiology of RAS blockade is needed as well as future studies to identify causality.
Department of Anesthesia and Perioperative Medicine, London Health Sciences Centre, ON, Canada. Craig.Railton@lhsc.on.ca
Craig J
CJ
Railton
Jacob
J
Wolpin
Jenny
J
Lam-McCulloch
Susan E
SE
Belo
D000368:Aged; D000758:Anesthesia; D047228:Angiotensin II Type 1 Receptor Blockers / Q000009:adverse effects* / Q000627:therapeutic use; D000806:Angiotensin-Converting Enzyme Inhibitors / Q000009:adverse effects* / Q000627:therapeutic use; D017544:Aortic Aneurysm, Abdominal / Q000601:surgery; D015331:Cohort Studies; D023381:Endpoint Determination; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D011183:Postoperative Complications / Q000401:mortality*; D012084:Renin-Angiotensin System / Q000187:drug effects*; D018401:Sample Size; D014656:Vascular Surgical Procedures / Q000401:mortality*
D047228:Angiotensin II Type 1 Receptor Blockers; D000806:Angiotensin-Converting Enzyme Inhibitors