Factors associated with mortality when chronic betablocker therapy is withdrawn in the peri-operative period in vascular surgical patients: a matched case-control study.
BACKGROUND
Withdrawal of chronic beta-blockade following vascular surgery is associated with peri-operative mortality. The aim of this study was to examine risk factors associated with mortality in patients where chronic beta-blockade was withdrawn.


METHODS
Two matched case-control studies were conducted, one of patients withdrawn from beta-blockade who survived and the other of patients who were maintained on beta-blockade and survived. Each case was matched with two controls. Three potential risk factors were analysed: the increase in heart rate postoperatively, the use of inotropes, and whether withdrawal for the first three postoperative days was more predictive than withdrawal for a single day. Multivariate conditional logistic regression was conducted.


RESULTS
The only independent predictor of in-hospital mortality was a change in the mean daily heart rate of > or = six beats per minute from the day of surgery to the third postoperative day, or death or discharge if this happened before the third day (OR 13.7, 95% CI: 1.7-110, p = 0.014). The area under the curve for the receiver operating characteristic curve was 0.787.


CONCLUSIONS
Use of a postoperative heart rate threshold may be clinically useful as an 'early warning system' in patients withdrawn from chronic beta-blockade in the peri-operative period.
Department of Anaesthetics, Nelson R Mandela School of Medicine and Inkosi Albert Luthuli Central Hospital, Durban, South Africa. biccardb@ukzn.ac.za
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Biccard
D000319:Adrenergic beta-Antagonists / Q000627:therapeutic use*; D000328:Adult; D005260:Female; D006331:Heart Diseases / Q000150:complications / Q000188:drug therapy / Q000401:mortality*; D017052:Hospital Mortality / Q000639:trends; D006801:Humans; D008297:Male; D008875:Middle Aged; D011300:Preoperative Care / Q000379:methods*; D057234:Preoperative Period; D012189:Retrospective Studies; D012307:Risk Factors; D013019:South Africa / Q000453:epidemiology; D015996:Survival Rate / Q000639:trends; D014652:Vascular Diseases / Q000150:complications / Q000601:surgery*; D014656:Vascular Surgical Procedures; D028761:Withholding Treatment
D000319:Adrenergic beta-Antagonists