Early invasive and conservative strategies for managing unstable angina or non-ST-segment-elevation myocardial infarction both received endorsements in the first guidelines on the topic from the American College of Cardiology and the American Heart Association since 2002.
Recommendation of a conservative, medically based option is a substantial change from the 2002 guidelines. The choice between an invasive or conservative strategy depends on patient stability, disease severity, other patient characteristics, and patient and physician preference. In contrast, the 2002 version presented the early-invasive strategy as the main option for most patients. The new guidelines were developed in collaboration with the American College of Physicians and other organizations (J. Am. Coll. Cardiol. 2007;50:652-726).
“What we're now saying is that a physician who chooses a conservative strategy is not a pariah. It's an acceptable strategy, except for unstable patients,” said Dr. Nanette K. Wenger, professor of medicine at Emory University, Atlanta, and a member of the guideline writing committee.
Other notable updates to the guidelines include a suggestion to use a formal scoring system to assess patient risk and help guide the choice between the two management options; longer use of the antiplatelet drug clopidogrel, for up to 1 year in all patients; and a broadening of the anticoagulant drug options to include two newer agents, fondaparinux and bivalirudin, in addition to the older drugs low-molecular-weight heparin and unfractionated heparin.
“It's a totally rewritten guideline, with 5 years worth of new evidence,” Dr. Wenger said in an interview.
Some of that evidence spoke to the efficacy of a conservative, noninvasive management strategy and a recognition that one approach does not fit all when treating patients with unstable angina or non-STEMI who do not have hemodynamic or electrical instability or persistent angina.
A key to making the conservative approach work is an early start to a broad range of medications during the first 24 hours of hospitalization, including aspirin, clopidogrel (Plavix), an anticoagulant, an oral β-blocker, and an oral ACE inhibitor. Other important steps include making sure that the patient is truly not at high risk by checking ventricular function with echocardiography or a nuclear test, and possibly by measuring serum levels of B-type natriuretic peptide, Dr. Wenger said.
“A lot of things applied early contribute to the safety of conservative management, which is what makes it an acceptable option,” said Dr. Wenger. “It's a sizable medical cocktail in the first 24 hours.” The guidelines noted that “use of aggressive anticoagulant and antiplatelet agents has reduced the incidence of adverse outcomes in patients managed conservatively.”
As backing for the conservative strategy, the guidelines cited results reported from the Invasive versus Conservative Treatment in Unstable Coronary Syndrome (ICTUS) trial, which showed that after 1 and 3 years of follow-up patients randomized to a selective invasive strategy had similar outcomes compared with patients managed with a routine invasive strategy (Lancet 2007;369:827-35). But the guidelines also noted that despite this finding in favor of a conservative strategy, a meta-analysis of seven trials including ICTUS found that overall an early invasive strategy led to fewer deaths or new coronary events (J. Am. Coll. Card. 2006;48:1319-25).
The guidelines call the conservative strategy preferable for certain patients, such as women who are at low risk of death or STEMI. That is because in low-risk women, the risk of complications from coronary catheterization, such as puncture site bleeding, exceeds the potential benefit from a percutaneous intervention, she said.
An important step when deciding between an invasive or conservative strategy is an early risk assessment of the patient. Although the guidelines allow physicians to make a qualitative assessment of high, intermediate, or low risk, on the basis of factors such as cardiac markers (especially troponin level), ECG, clinical findings, pain, and history, they recommend going further and using one of the formal scoring systems that have been validated during the past few years: the Thrombolysis in Myocardial Infarction (TIMI), the Global Registry of Acute Coronary Events (GRACE), or the Platelet IIb/IIIa in Unstable Angina: Receptor Suppression Using Integrilin Therapy (PURSUIT) scoring methods.
“We thought it was a little early to say that everyone has to use a formal scoring system on every patient, but we're pushing people in that direction,” said Dr. Jeffrey L. Anderson, associate chief of cardiology at LDS Hospital in Salt Lake City and chairman of the guidelines committee. “We hope that people will become more familiar with scoring over the next few years and that eventually” it will be used routinely, he said in an interview.
Other important, new elements in the guidelines deal with antiplatelet and anticoagulant therapy. In addition to daily aspirin, which is continued indefinitely, all patients should start on clopidogrel as soon as possible and continue on it for a year if they are treated conservatively or get a bare-metal coronary stent, and continue for at least a year on clopidogrel if they receive a drug-eluting coronary stent.