麻豆传媒

Patients taking beta-blockers when they underwent noncardiac, nonvascular surgery had better outcomes than those not taking the drugs, an observational study showed.

Among patients included in Veterans Health Administration databases, use of a beta-blocker on the day of, or the day after, an operation was associated with a significantly lower risk of all-cause mortality at 30 days (RR 0.73, 95% CI 0.65 to 0.83), according to Martin London, MD, of the San Francisco VA Medical Center, and colleagues.

In addition, perioperative beta-blocker use was associated with a lower risk of the composite of Q-wave myocardial infarction (MI) or nonfatal cardiac arrest (RR 0.67, 95% CI 0.57 to 0.79), the researchers reported in the April 24 issue of the Journal of the American Medical Association.

Both associations were confined to patients undergoing nonvascular surgery with at least two of the following six Revised Cardiac Risk Index factors:

• High-risk surgery
• Cerebrovascular disease
• Ischemic heart disease
• Congestive heart failure
• Diabetes
• Renal insufficiency

"Although assessment of the cumulative number of Revised Cardiac Risk Index predictors might be helpful to clinicians in deciding whether to use perioperative beta-blockade, the current findings highlight a need for a randomized, multicenter trial of perioperative beta-blockade in low- to intermediate-risk patients scheduled for noncardiac surgery," London and colleagues wrote.

The study "basically forces us to reevaluate whether we should be giving beta-blockers routinely in all patients who are going for noncardiac surgery," commented Sabu Thomas, MD, of the University of Rochester Medical Center in New York.

The use of beta-blockers in the perioperative period among patients undergoing major noncardiac surgery is controversial, according to the researchers.

The POISE trial reported in 2007 showed that patients undergoing noncardiac surgery who were randomized to perioperative metoprolol, started 2 to 3 hours before the operation, had fewer MIs and atrial fibrillation events, but greater risks of death and severe stroke compared with those randomized to placebo.

Those findings prompted the American College of Cardiology and American Heart Association to revisit guidelines regarding the issue. Now, the only Class I indication in the guidelines is to continue use of beta-blockers in patients who are already taking them.

To further explore the issue, London and colleagues performed a retrospective analysis of data from system-wide VA healthcare databases. The study included 136,745 patients (mean age 64.4, 96.3% male) treated at 104 VA medical center from January 2005 through August 2010.

Overall, 40.3% of the patients were exposed to beta-blockers -- most commonly metoprolol tartrate and atenolol -- on the day of or day following surgery. The rate was higher among those undergoing vascular surgery than among those undergoing nonvascular surgery (66.7% versus 37.4%, P<0.001).

The rate also increased along with the number of Revised Cardiac Risk Index factors that were present, from 25.3% for no risk factors to 71.3% for at least four risk factors (P<0.001).

The rate of exposure dropped significantly during the study period, from 43.5% in 2006 to 36.2% in 2010 (P<0.001), probably related to the release of the POISE results and the resulting change to the recommendations, according to the researchers.

In the first 30 postoperative days, 1.1% of patients died from any cause and 0.9% had a Q-wave MI or nonfatal cardiac arrest.

After using propensity scoring to account for the patients' likelihood of being exposed to beta-blockers, perioperative beta-blocker use was associated with significantly reduced risks of both outcomes, but only among those with two or more of the Revised Cardiac Risk Index factors (for mortality) and two or three of the factors (for the composite cardiac morbidity outcome).

There was no association between beta-blocker exposure and stroke, which contrasts with the findings of the POISE trial.

"Analysis of existing randomized trials suggests that either timing of initiation and or dose of beta-blocker are important covariates," the authors wrote, noting that their analysis did not include dosing information.

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