EVIDENCE-BASED ANSWER
Patients with moderate to high cardiac risk (a Revised Cardiac Risk Index [RCRI] score of 2 or higher [TABLE]) have a reduced risk of in-hospital death following perioperative beta-blocker therapy (strength of recommendation [SOR]: B, based on a large retrospective cohort study). There is, however, no proven benefit to perioperative beta-blocker therapy without prior cardiac risk stratification (SOR: A, based on systematic reviews).
Perioperative beta-blockers reduce cardiovascular risk even more when a long-acting beta-blocker (atenolol) is chosen over a shorter-acting one (metoprolol) (SOR: B, based on a retrospective cohort study), and when this therapy is titrated to a target heart rate of <65 BPM (SOR: B, based on cohort studies).
Perioperative beta-blocker therapy is most effective when initiated at least 30 days before surgery and continued throughout the hospital stay (SOR: C, expert opinion extrapolated from systematic review). Patients already on beta-blockers before surgery should continue at least through the perioperative period (SOR: C, expert opinion).
Clinical commentary
Who better than you to reduce your patient’s risk?
Vincent Lo, MD
San Joaquin Family Residency, French Camp, Calif
Family physicians are in an excellent position to assess and reduce their patients’ risks of complications from elective surgery.
While perioperative beta-blockers do not benefit every surgical patient, they do benefit certain high-risk patients. In fact, these same high-risk patients are often candidates for chronic beta-blocker therapy, according to current ACC/AHA guidelines. Thus, an upcoming surgery gives us another opportunity to identify these patients and get them treated.
Evidence summary
Studies without risk stratification find little benefit from beta-blockers
A systematic review including 25 randomized controlled trials (RCTs) evaluated perioperative beta-blocker therapy for noncardiac surgery in a total of 2722 patients who were not stratified according to cardiac risk status.1
Perioperative beta-blockers produced no significant effect on:
- all-cause mortality (odds ratio [OR]=0.78; 95% confidence interval [CI], 0.33–1.87),
- acute myocardial infarction (OR=0.59; 95% CI, 0.25–1.39),
- atrial fibrillation/flutter and other supraventricular arrhythmias (OR=0.43; 95% CI, 0.14–1.37), or
- length of hospital stay (weighted mean difference, –5.6 days; 95% CI, –12.2, 1.04).
However, in this review perioperative beta-blocker therapy reduced perioperative myocardial ischemia (OR=0.38; 95% CI, 0.21–0.69), and increased 2 adverse outcomes: hemodynamically significant bradycardia (OR=1.98; 95% CI, 1.08– 3.66) and hypotension requiring treatment (OR=2.52; 95% CI, 1.94–3.28).1 This study was limited by the inconsistent definition and assessment of outcomes among the individual trials.
No effect on total mortality, but a benefit in a composite outcome. An earlier systematic review with 22 RCTs and 2437 total patients, that was also not stratified according to cardiac risk status, found no effect from perioperative beta-blockers on total mortality or cardiovascular mortality alone. However, it did demonstrate a composite outcome of reduced cardiovascular mortality, reduced nonfatal myocardial infarction, and reduced nonfatal cardiac arrest (relative risk [RR]=0.44; 95% CI, 0.20–0.97) 30 days after surgery.2
Beta-blockers benefit certain high-risk patients
A retrospective cohort study evaluated the effect of perioperative beta-blocker therapy on perioperative mortality, according to preoperative RCRI assessment.3 The study population included 663,635 adults (mean age, 62 years) undergoing major noncardiac surgery at 329 US hospitals. Researchers calculated individual RCRI scores (TABLE).4 Half the patients had an RCRI of 0, 38% had an RCRI of 1, 10% had an RCRI of 2, and only 2% had an RCRI of 3 or greater.
Be wary of beta-blockers in low-risk patients. In the 580,665 patients with low cardiac risk, perioperative beta-blocker therapy increased the risk of in-hospital death: for all patients with an RCRI of 0: OR=1.36 (95% CI, 1.27–1.45); number needed to harm (NNH)=208; for all patients with an RCRI of 1: OR=1.09 (95% CI, 1.01–1.19); NNH=504).
A different story for high-risk cardiac patients. Perioperative beta-blocker therapy reduced the risk of in-hospital death in patients with an RCRI of 2 (OR=0.88; 95% CI, 0.80–0.98; number needed to treat [NNT]=227), an RCRI of 3 (OR=0.71; 95% CI, 0.63–0.80; NNT=62), or an RCRI of 4 or more (OR=0.58; 95% CI, 0.50–0.67; NNT=33).
TABLE
Before surgery, calculate your patient’s cardiac risk
| Assign 1 point for each of the following, and total: | ||
| ||
| POINTS | CLASS | RISK OF MAJOR CARDIAC EVENT* |
| 0 | I | 0.4% |
| 1 | II | 0.9% |
| 2 | III | 6.6% |
| 3+ | IV | 11% |
| *Major cardiac event includes myocardial infarction, pulmonary edema, ventricular fibrillation, primary cardiac arrest, and complete heart block. | ||
| Source: Lee et al, 1999.4 | ||