New clinical trial data have prompted the American Heart Association and American College of Cardiology to update parts of their joint guidelines for care of patients with acute ST-elevation myocardial infarctions, with the revised guidelines to be published in the January 15 print issues of Circulation and Journal of the American College of Cardiology. The guidelines are currently available online at www.americanheart.org and www.acc.org.

Each year, almost half a million Americans have an ST-elevation infarction.
"Our recommendations for the initial treatment of ST-elevation MI continue to reinforce the goal of restoring blood flow to the heart as quickly as possible," said Elliott Antman, MD, chair of the guideline writing group, director of the coronary care unit at Brigham and Women's Hospital and professor of medicine Harvard Medical School. "Data show that better systems of care, leading to faster times to reperfusion, result in better outcomes for patients with STEMI. One underutilized but effective strategy for improving STEMI systems of care is to expand the use of prehospital 12-lead electrocardiography programs by emergency medical systems that provide advanced life support. This provides the early diagnosis that can set into motion the appropriate treatment strategy."

The recommendations clarified that emphasis on percutaneous coronary intervention (PCI) should not obscure the importance of fibrinolytic therapy. Patients presenting to a hospital with angioplasty capability should be treated with primary angioplasty within 90 minutes of first medical contact as a systems goal.

The same 90-minute goal applies for hospitals without angioplasty capability as long as a patient can be transferred and receive treatment within the 90-minute window. However, patients who cannot be transferred in time for treatment within 90 minutes should be treated with fibrinolytic therapy within 30 minutes of hospital presentation as a systems goal unless fibrinolytic therapy is contraindicated.

The update also includes clarification of which patients are candidates for early intravenous beta-blocker therapy, now noting that such treatment should not be administered to patients who have any of the following: 1) signs of heart failure; 2) evidence of a low output state; 3) increased risk for cardiogenic shock; or 4) other relative contraindications to beta blockade (including second- or third-degree heart block, active asthma, or reactive airway disease).

The update also includes new information on how to make the transition to catheterization lab for patients who initially received fibrinolytic treatment. This includes facilitated and rescue procedures. Facilitated percutaneous coronary intervention refers to a strategy of planned immediate intervention after administering fibrinolytic drugs before the procedure. Rescue procedures occur after fibrinolytic treatment has failed to restore blood flow to the affected portion of the heart.

According to the update, potential advantages of facilitated intervention include quicker restoration of blood flow, less myocardial damage, improved patient stability and greater procedural success. Potential risks include increased bleeding complications, especially in older patients.

Despite the potential advantages, clinical trials of facilitated intervention procedures have not demonstrated benefit in reducing infarct size or improving outcomes. Thus, the update states that full-dose fibrinolytic therapy followed by immediate angioplasty may be harmful. However, facilitated percutaneous coronary intervention using regimens other than full-dose fibrinolytic therapy might be considered for restoring blood flow when all of the following are present: 1) patients are at high risk; 2) procedure is not immediately available within 90 minutes; and 3) bleeding risk is low.

Rescue procedures are recommended for patients who have received fibrinolytic therapy and have any of the following: 1) cardiogenic shock in patients less than 75 years of age who are suitable candidates for revascularization; 2) severe congestive heart failure and/or pulmonary edema; 3) hemodynamically compromising ventricular arrhythmias.

The guidelines also include new recommendations on anticoagulants. Patients undergoing reperfusion with fibrinolytics should receive anticoagulant therapy for at least 48 hours and preferably for the duration of the initial hospital stay, up to eight days.

According to the update, clopidogrel should be added to aspirin in patients with ST-elevation infarcts regardless of whether they undergo reperfusion with fibrinolytic therapy or do not receive reperfusion therapy. Treatment with clopidogrel should continue for at least 14 days.

Recommendations regarding the initial treatment of acute infarctions retain the same goal - to restore blood flow to the heart as quickly as possible, primarily through percutaneous coronary intervention.

Finally, among the most notable changes in the update is the recommendation that patients who routinely use COX-2 inhibitors and non-steroidal anti-inflammatory drugs - except aspirin - should stop taking them while being treated for an acute infarction.

"The updated opinion on COX-2 inhibitors and other nonsteroidal anti-inflammatory drugs comes along with further clarification and updates on other drug treatments, such as intravenous beta blocker therapy, and new recommendations about new drug treatments that should be used in patients with St-elevation myocardial infarction," Antman said.

The update now says to stop nonsteroidal anti-inflammatory drugs and COX-2 inhibitors during the acute phase of treatment in patients with St-elevation infarction. After initial treatment, there are recommendations for a "rigorous review of any ongoing needs for pain control at the time of hospital discharge, followed by a five-step process for choosing appropriate pain medicines," Antman said. In all cases, the lowest effective doses should be used for the shortest possible time and COX-2 selective nonsteroidal anti-inflammatory drugs should be considered only as a last resort.