Fig. 2. Kaplan-Meier Survival curves for different patterns of use of perioperative β-adrenergic receptor blockade (β-blockade) over time. The None group consisted of patients who did not receive β-blockers before, during, or after surgery. The Addition group included patients who did not have β-blockers before surgery but who received at least one dose of β-blockers after surgery as either an inpatient or outpatient. The Withdrawal group consisted of patients who were receiving β-blockers before surgery but did not receive a single dose after surgery. The Continuous group included patients who were receiving β-blockers before surgery and who received at least one dose after surgery.