Approximately 100,000 of the 400,000 patients per year in the United States who undergo cardiac surgery and 1.5 million of the 30 million who undergo non-cardiac surgery suffer perioperative cardiovascular morbidity resulting in 50,000 myocardial infarctions and 20,000 deaths a year at a cost exceeding $20 billion annually.^1,2 Perioperative Cardiac Risk Reduction Therapy (PCRRT) using prophylactic beta-blockade administered perioperatively reduces the incidence of perioperative cardiac death between 50% and 90% in patients at risk who undergo non-cardiac surgery.^3,4 PCRRT with clonidine, an alpha-2 agonist, reduces the incidence of postoperative mortality death 50% in patients who undergo non-cardiac surgery.⁵

In 1996, the American Heart Association and the American College of Cardiology published medical guidelines6 and in 20037 they revised them, recommending the perioperative administration of beta-blockers to patients who required them in the recent past to control symptoms of angina or patients with symptomatic arrhythmias or hypertension, as well as to patients at high cardiac risk owing to the finding of ischemia on preoperative testing or who are undergoing vascular surgery. They also recommend that beta blockers be administered to patients with untreated hypertension, known coronary disease, or major risk factors for coronary disease (Class IIa). Alpha-2 agonist therapy is recommended for the same population as a Class IIb recommendation.

What is the justification for these recommendations by the American College of Cardiology? The initial efforts at reducing cardiac risk consisted of risk stratification.⁸ However, risk stratification merely identifies fixed risk factors (coronary artery disease, peripheral vascular disease, age, diabetes, smoking, hypercholesterolemia, hypertension) it does not actually reduce risk. In 1990, Mangano et. al. identified risk factors common to the risk stratification studies but also identified the additional risk factor of perioperative myocardial ischemia, a risk factor that could be modified.¹ Many authors tried to identify perioperative tests that could predict perioperative morbidity, but no preoperative test has been proven successful at predicting morbidity and mortality.^9,10 Moreover, even if a preoperative test were able to predict perioperative morbidity, what could be done to lower that risk? Any therapy designed to reduce cardiac risk must reduce total risk and it is difficult to add the risk of a procedure (CABG or PCI) to a second procedure (non-cardiac surgery) and get a lower total risk. The CARP trial definitively demonstrated that coronary-artery revascularization before elective vascular surgery does not significantly alter short or long-term outcome. ¹¹ On the basis of these data, the strategy of coronary-artery revascularization before elective vascular surgery among patients with stable cardiac symptoms cannot be recommended. ¹¹ Percutaneous coronary angioplasty with intracoronary stents (PCI) prior to elective surgery has been associated with a 20% operative mortality.¹² The MAS-II trial, a randomized trial comparing CABG, PCI, and medical therapy, showed a survival advantage to medical therapy at one year.¹³

Given the failure of standard cardiac risk stratification followed by coronary revascularization to reduce operative risk, a number of clinical trials of medical therapy have been completed.^3,14-22 This extensive search for a medical therapy to reduce perioperative myocardial ischemia and cardiac death identified two generic therapies which reduce the risk of perioperative cardiac morbidity and mortality (beta blockers^3,18,19,23 and clonidine²⁴). Prophylactic beta blocker therapy reduces perioperative mortality 50 to 90%.^3,18,19,23 Prophylactic clonidine therapy reduces 30 day mortality 7 fold.²⁴ The cost per life saved is between $3 and $600 depending on PO or IV therapy. The American Heart Association and American College of Cardiology recognized the profound importance of prophylactic perioperative beta blocker therapy and made it a level I indication in 1996 for patients with known coronary artery disease or known vascular disease (higher risk).

There has been some discussion of how to treat patients at lower risk (those with two risk factors). In the VA studies^3,14,24, treating patients with two risk factors reduced total operative mortality and improved long term survival. Other authors agree that higher risk patients should definitely be on beta blockers but are less certain of the benefits in lower risk patients.^25-27 London et. al. concluded that evidence for the efficacy of perioperative beta blockers is strong and the established clinical guidelines of the ACC/AHA should be used to guide the institution and maintenance of perioperative beta blocker therapy in patients at risk.²⁷