Several studies have examined the risks and benefits of perioperative beta blocker therapy. Although each study was designed to answer the same question, most resulted in different answers. It does appear that beta blocker therapy in the perioperative period decreases the number of cardiac events, such as myocardial infarction (MI). However, this benefit comes at the cost of increased hypotension, stroke, and, in some studies, composite death. The most recent systematic review examining the data came with the following recommendations [8]:

Statin therapy has been shown to be effective for primary and secondary prevention of cardiac events. Although most of the data related to statin therapy come from observational trials, the composite power suggests a protective effect on the preoperative use of these agents in either vascular surgery or high-risk patient populations [9]. The most recent guidelines therefore recommend that those on statins continue their therapy in the perioperative period. They also allow for the initiation of therapy in patients undergoing vascular surgery, as well as patients with clinical indications undergoing medium- or high-risk procedures. The mechanism of benefits from perioperative statin therapy are unknown, but are likely related to pleotropic, lipid lowering effects, as well as anti-inflammatory effects. Additionally, it is not known when is the optimal time to begin therapy, nor is it clear what the duration of therapy should be.

Early data on the role of alpha-2 agonists such as clonidine and mivazerol suggested that the perioperative use of these agents, especially in vascular surgery was protective. The POISE-2 (PeriOperative ISchemic Evaluation-2) trial—a large, multicenter, international, blinded study—was unable to demonstrate the benefit of clonidine. Additionally, it was found that clonidine use in the perioperative period was associated with an increase in the rate of nonfatal cardiac arrest and clinically significant hypotension. It is therefore not recommended to use alpha-2 agonists in the perioperative period for the prevention of cardiac events. Patients who are on alpha-2 agonists for other indications (such as hypertension) should continue their dose of medication; or ideally, be weaned off their medication and started on other therapies prior to surgery. The abrupt discontinuation of these medications can result in rebound hypertension, headache, agitation, and tremor.

The most current guidelines have no recommendations for starting calcium channel blockers in the perioperative period. A meta-analysis from 2003 examined the use of calcium channel blockers in patients with coronary disease and found trends toward reduced death and MI. It should be noted that these differences were mostly attributable to the use of diltiazem. Neither dihydropyridines nor verapamil had effects on mortality or MI; however, the use of either verapamil or diltiazem seemed to be protective for the development of perioperative supraventricular tachycardia (SVT). The authors note that the results are trends and that larger more robust studies are needed to confirm the results. As such, although it would be prudent to continue these medications in the perioperative period it is not recommended to begin therapy unless otherwise indicated.

Approved for multiple indications from hypertension to prevention of diabetic nephropathy, ACE andangiotensin receptor blockers (ARBs) are some of the most commonly prescribed medications. Perioperative data on the risk/benefit profile of continuation of these medications is limited mostly to observational data. The largest study examined almost 80,000 patients (of which 13% were on ACE-I) and found that patients on therapy had an increased frequency of intraoperative hypotension. This has been found in other studies as well, with one showing an incidence of hypotension of 50% in patients on therapy. Despite the increase in hypotension, there appears to be no increased incidence of death, MI, or renal failure. The evidence on discontinuation of these medications prior to surgery is poor. There is data, however, on the risks of not restarting these medications in the perioperative period, which seems to be the greatest risk of discontinuation. In fact, maintaining the continuity of these medications in the setting of treatment for heart failure or hypertension is supported by other guidelines. Additionally, a more recent cohort study including 30,000 patients found an increased risk of mortality in patients in whom restarting ARB therapy was delayed. Due to the lack of demonstration of real harm to patients who continue therapy in the perioperative period as well as the potential risks of discontinuation, continuing these medications in the perioperative period is reasonable. If ACE/ARB therapy must be withheld, it should be restarted as soon as possible.

Recommendations to discontinue oral diabetic medication remain controversial. While elevated blood sugar levels have been shown to retard wound healing, an ideal blood sugar level has not been determined. While many laboratory scales consider hyperglycemia to be values above 120 mg/dl, it is probably more important to consider the individual and the level at which he most usually functions. Thus, values of 150–170 mg/dl may be considered normal for many. Should testing indicate values exceeding 180 mg/dl, oral medications should be discontinued and an infusion of regular insulin commenced perioperatively. Further evaluation by an endocrinologist is indicated with repeated blood glucose checks.