Factors associated with mortality when chronic betablocker therapy is withdrawn in the peri-operative period in vascular surgical patients: a matched case–control study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The aim of this study was to examine risk factors associated with mortality in patients where chronic beta-blockade was withdrawn. METHODS: Two matched case–control studies were conducted, one of patients withdrawn from beta-blockade who survived and the other of patients who were maintained on beta-blockade and survived.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 ≥ 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. CONCLUSION: Use of a postoperative heart rate threshold may be clinically useful as an ‘early warning system’ in patients withdrawn from chronic beta-blockade in the peri-operative period.