Physician's Weekly Article - A Focused Update for Managing STEMI Patients

       New data from clinical trials assessing various aspects of ST-elevation myocardial infarction, or STEMI, has led to an updated set of joint guidelines to improve outcomes in these patients.

      Almost 500,000 Americans each year have an ST-elevation myocardial infarction (STEMI), but these events can be quickly recognized and treated to reduce further heart damage. In 2004, the American College of Cardiology (ACC) and American Heart Association (AHA) released joint guidelines for treating STEMI. Since then, new clinical trial data on a variety of aspects of STEMI care have emerged, prompting ACC/AHA to update portions of the 2004 joint guidelines in late 2007. In addition to other data, late-breaking clinical trials presented at the 2005 and 2006 annual scientific meetings of the ACC, AHA, and European Society of Cardiology were reviewed to identify key information that has since impacted the guideline recommendations.

      Published in the January 15, 2008 issues of Circulation and the Journal of the American College of Cardiology (www.cardiosource.com/guidelines), the new ACC/AHA guidelines reinforce the goal of restoring blood flow to the heart as quickly as possible during the initial treatment of STEMI. “We have evidence showing that improved systems of care can lead to faster times to reperfusion, resulting in better outcomes for patients with STEMI,” says Elliott M. Antman, MD, FACC, FAHA, who chaired the guideline writing group.

      Facilitated & Rescue PCI

      The 2007 ACC/AHA guidelines for STEMI clarify data on administering a strategy of planned immediate PCI after an initial pharmacologic regimen has been given, also known as facilitated PCI. “Several regimens have been used to evaluate facilitated PCI,” Dr. Antman explains. “These include full-dose fibrinolytic therapy, a combination of a fibrinolytic therapy plus a glycoprotein (GP) IIb/IIIa, or a GP IIb/IIIa inhibitor alone. Despite promising initial results of small trials, there’s no evidence of their impact on improving mortality or reinfarction rates. In fact, these regimens increase the risk of bleeding, so the new guidelines recommend against a planned reperfusion strategy using full-dose fibrinolytic therapy followed by immediate PCI.” However, facilitated PCI using regimens other than full-dose fibrinolytic therapy should be considered only when patients are at high risk, when PCI is not available within 90 minutes, and when the bleeding risk is low. “This recommendation opens the door for some future research,” notes Dr. Antman.

      According to the guidelines, patients with STEMI presenting to a hospital with PCI capability should be treated with primary PCI within 90 minutes of first medical contact (Table 1). This systems goal also stands for hospitals without PCI capability, but only if patients can be transferred and receive treatment within the 90-minute window. On the other hand, patients who cannot be transferred to a PCI center and undergo PCI within 90 minutes should be treated with fibrinolytic therapy within 30 minutes of presenting to the hospital unless such therapy is contraindicated.

      The update also includes new information on rescue PCI, which refers to the need for PCI after fibrinolytic treatment has failed to restore blood flow to the heart. “The guidelines now recommend that proceeding with rescue PCI is reasonable in patients with hemodynamic or electrical instability and/or persistent ischemic symptoms,” Dr. Antman says. “In addition, PCI of a hemodynamically significant stenosis in infarct arteries more than 24 hours after STEMI may still be considered as part of an invasive strategy when fibrinolysis is successful or patients do not undergo primary reperfusion. However, the guidelines now recommend that PCI of a totally occluded infarct artery more than 24 hours after STEMI is not advisable in asymptomatic patients with one- or two-vessel disease if they are hemodynamically and electrically stable and do not have evidence of severe ischemia.”

      Clarifying ß-Blocker Use

      The 2007 ACC/AHA update also helps clarify which patients with STEMI are candidates for early intravenous (IV) ß-blocker therapy. STEMI patients with several characteristics should not be administered IV ß-blockers (Table 2). “The 2004 guidelines were based on studies that showed a reduced incidence of subsequent reinfarction and recurrent ischemia in patients receiving both fibrinolytic therapy and IV ß-blockers,” notes Dr. Antman. “However, more recent studies have uncovered uncertainty about the use of IV beta blockers in the setting of fibrinolytic therapy.” Two randomized trials of IV beta blockade found that early ß-blocker therapy in myocardial infarction did not significantly reduce mortality.

      Using Ancillary Therapies

      A series of new recommendations are available in the updated guidelines for ancillary therapies in STEMI patients. For example, selective cyclo-oxygenase-2 (COX-2) inhibitors and other nonselective nonsteroidal antiinflammatory drugs (NSAIDs) have been associated with increased heart risks; this risk appears to be amplified in patients with established heart disease (Table 3).

      An AHA scientific statement on the use of NSAIDs concluded that the risk of cardiovascular events is proportional to COX-2 selectivity and the underlying risk in STEMI patients. “Non-pharmacological approaches are recommended as the first line of treatment,” explains Dr. Antman, “followed by a stepped-care approach to pharmacological therapy. The updated guidelines now recommend discontinuing NSAIDs when patients present to the cardiac care unit with STEMI. When preparing STEMI patients for discharge, it’s recommended that physicians review the need for long-term musculoskeletal pain therapy. Essentially, the lowest effective doses should be used for the shortest possible time. COX-2 selective NSAIDs should be considered only as a last resort in all STEMI cases.”

      Elliott M. Antman, MD, FACC has indicated to Physician’s Weekly that he is a senior investigator in the TIMI Study Group. That study group has received grants from Accumetrics, Amgen, AstraZeneca, Bayer Healthcare, Beckman Coulter, Biosite, Bristol-Myers Squibb, CV Therapeutics, Eli Lilly, GlaxoSmithKline, Inotek Pharmaceuticals, Integrated Therapeutics, Merck, Millennium, the NIH, Novartis, Nuvelo, Ortho-Clinical Diagnostics, Pfizer, Roche Diagnostics, Roche Diagnostics GmbH, Sanofi-Aventis, Sanofi-Synthelabo Recherche, and Schering-Plough. Dr. Antman has also received honoraria from or been on the speaker’s bureau for Eli Lilly and Sanofi-Aventis. He has also worked as a consultant/advisory member for Sanofi-Aventis.