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Now is the time to reappraise ACC/AHA guidelines on beta-blockers, noncardiac high-risk vascular surgery
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Perioperative MI and its subsequent consequences remain a dreaded complication after noncardiac vascular surgery. In the 1970s, recommendations were to avoid the perioperative use of beta-blockers due to possible harm secondary to beta-blocker–induced bradycardia and hypotension. However, subsequent data showed that there was a dose-related reduction in the incidence of MI after beta-blocker therapy.
In the 2002 American Heart Association/American College of Cardiology guidelines, the pendulum swung markedly, with recommendations to use beta-blockers perioperatively in the majority of patients. These guidelines were updated and endorsed in 2007 with Class IB to Class IIB indications for those with CAD, CAD equivalent, inducible ischemia and noncardiac vascular surgery.
However, published data do not substantiate these recommendations. In 2009, there is proven benefit of beta-blocker use after an MI, unstable angina and in patients with congestive HF with reduced left ventricular systolic function. Beta-blockers are also useful in patients with stable angina, as these agents relieve angina and exert anti-ischemic effects. In patients with atrial fibrillation, beta-blockers control ventricular response and provide symptomatic improvement. Patients with these conditions are often assigned to long-term beta-blocker therapy and are often continued on their therapy and invariably excluded from any outcome trials. In the absence of these indications, there are only a few small randomized studies and large observational studies with results that show benefit. Results of other large randomized, placebo-controlled studies show either no benefit or even harm with routine perioperative use of beta-blockers.
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Earlier double blind studies with atenolol and bisoprolol were carried out in only a small number of patients and have been recently criticized due to the small number of patients studied, few outcome events and inadequate accounting of events in the final analysis. Results of recent large randomized trials with metoprolol have either shown no benefit or an increase in mortality and stroke, despite a reduction in perioperative MI. Some of these studies have been criticized due to aggressive use of beta-blockers (IV and oral) immediately before surgery and during the immediate perioperative period after noncardiac vascular surgery. Severe bradycardia and hypotension after aggressive beta-blockade therapy have been blamed for the increase in mortality and nonfatal stroke rates compared with placebo in the POISE trial. It has been argued that only the use of oral beta-blockers with gradual titration to heart rates between 60 bpm and 70 bpm over a period of two to four weeks before vascular surgery is beneficial. These recommendations may appear reasonable but are not based on any large outcome trials.
A first principle of any therapy is to do no harm. In the absence of large outcome data confirming benefit of beta-blockers perioperatively, there remains confusion as to what to recommend. At present, routine use of beta-blockers perioperatively during noncardiac vascular surgery in the absence of a history of MI, unstable or stable angina, HF due to a reduced LV systolic function and AF with rapid ventricular response cannot be justified despite the presence of other known risk factors of poor perioperative outcomes after vascular surgery.
There is confusion out there, and I often wonder what a poor doctor is supposed to recommend in the absence of sound scientific data. Large placebo-controlled, adequately powered randomized trials in 50,000 to 100,000 patients are urgently needed to answer this important issue of public concern.
Udho Thadani, MD, MRCP, FRCPC, FACC, FAHA, is Professor Emeritus of Medicine and Consultant Cardiologist at the University of Oklahoma Medical Center and District VA Medical Center in Oklahoma City. He is also a member of the CHD and Prevention section of the Cardiology Today Editorial Board.
For more information:
- Chopra V. Am J Med. 2009;122:222-229.
- Feringa HHH. Circulation. 2006;114:I-344–I-349.
- Fleisher LA. Circulation. 2007;116:1971-1976.
- POISE Study Group. Lancet. 2008;371:1839-1847.
- Thadani U. Preoperative cardiac evaluation: What is the best medical therapy? Presented at: American College of Cardiology 58th Annual Scientific Session; March 28-31, 2009; Orlando, Fla.