New cardiovascular guidelines contain some new recommendations on pharmacotherapy
According to the American College of Cardiology (ACC) and the American Heart Association (AHA), each year about one million people experience significant cardiac complications as a result of surgery. The ACC and AHA recognized that better screening and care could help prevent many of these complications, particularly for noncardiac surgeries, and they teamed up to create Guidelines for Perioperative Cardiovascular Evaluation for Noncardiac Surgery.
The two organizations have revised and updated the guidelines to include research results gathered since the last publication in 1996. Although many of the revisions involve physical evaluation and testing, some new drug information will be of interest to pharmacists.
Beta-blockers are the real heroes in this story. Several studies have indicated that these drugs prevent cardiac complications in patients undergoing surgery. They help keep blood pressure under control, which lowers the incidence of coronary ischemic episodes during and after surgery. They have been documented to reduce the occurrence of atrial fibrillation in the post-operative period, and also to effectively resolve supraventricular arrhythmias. Other studies have found that patients with coronary artery disease (CAD), or who are at risk for this condition, have lower mortality and cardiovascular complication risk when beta-blockers are started preoperatively.
The guidelines urge clinicians to start beta-blockers days or weeks before surgery, if possible, and to select a dose to achieve a resting heart rate of 50 to 60 beats per minute. This therapy is suggested for patients with hypertension, symptomatic arrhythmias, high cardiac risk (preoperative ischemia), and patients who have used beta-blockers for angina. It may also be beneficial for patients with CAD, or with risk factors for the disease.
"Beta-blockers seem to be the underlying theme," said Cynthia Sanoski, Pharm.D., after reviewing the changes to the guidelines. Sanoski is a cardiovascular clinical specialist and an assistant profes-sor of clinical pharmacy at the Philadelphia College of Pharmacy. Most of this information, she said, is already widely known and in use. Sanoski agreed with the ACC and AHA panel's assessment of beta-blockers. "It's one of those [classes of] drugs you can pretty much use for any cardiovascular disorder."
Untreated hypertension can greatly increase the risk of cardiac complications during surgery. "Unfortunately, all too few patients with hypertension are treated, and fewer yet have their hypertension controlled," said the ACC and AHA in the guidelines. Diagnosing these patients and getting their blood pressure under control is a much-desired side effect of presurgical evaluation. "Basically, I think it's great," said Mark Cziraky, Pharm.D., FAHA (Fellow of the American Heart Association), after reviewing the updated hypertension section. "[They're] trying to identify people who have not been identified," he said. "I think it's a great opportunity."
The guidelines do not recommend delaying surgery if hypertension is present. Instead, treatment of mild hypertension may begin after surgery. Patients with stage 3 hypertension (greater than 179 mmHg systolic or 109 mmHg diastolic) should be treated before surgery. Beta-blockers are recommended, of course.
Cziraky, a pharmacist at Health Core in Newark, Del., is concerned that elevated blood pressure before surgery may be situational and may or may not be present after surgery. This should be evaluated and treated, if necessary, postsurgery. He realizes the guidelines are geared toward getting the patient through surgery successfully and not necessarily aimed at long-term management of patients. "They're just focusing on controlling it at that point," he said, referring to the presurgery period. However, he is still very supportive of the guidelines' goal to identify and treat hypertensive patients.
Diabetes mellitus (DM) is another disease that can go undiagnosed for years. Preoperative evaluation is a good time to identify patients with DM. Hypertension, which is a common problem for diabetics, can be diagnosed and treated, and blood sugar levels can be addressed.
There are other concerns, too. Studies have found that people with diabetes are at increased risk for CAD and have a higher incidence of myocardial infarction and silent ischemia. Older patients with DM are also more likely to develop heart failure postsurgery, even if they are already being treated with ACE inhibitors.
In light of all this, the new guidelines have retracted the former recommendation regarding insulin therapy. Instead of loose control postsurgery to prevent hypoglycemia, the guidelines now recommend continuous insulin infusion for tighter control and prevention of cardiac complications. Phil Chase, R.Ph., CDE (Certified Diabetes Educator), agreed with this change. When patients undergo surgery, he said, blood glucose levels increase, and that decreases healing. Continuous administration of insulin and monitoring of patients should help counteract this effect. "It's more nursing, but it makes more sense," he said.
Chase, a pharmacist at Western State Hospital in Lakewood, Wash., also liked the fact that presurgical evaluation could help identify patients with DM and hypertension. He cited large-scale studies of DM patients that found that treating this group promptly and rigorously led to better long-term prognoses. "There are a lot of things with patients that you can't change, but you can change their blood pressure, you can change their lipids, you can change their blood glucose levels and other risk factors," Chase said. "By decreasing blood pressure, by decreasing lipids, and by controlling blood glucose, you can decrease risk factors and long-term complications."
The guidelines can be viewed at these Web sites:
Jillene Lewis. Guidelines for noncardiac surgery push beta-blockers. Drug Topics 2002;5:26.