DALLAS, August 24 -- Because of the explosion of new knowledge about the treatment of heart attacks, the American College of Cardiology (ACC) and the American Heart Association have updated important sections of guidelines on heart attack treatment, previously published in November 1996. For the first time, the new recommendations will appear first on the web sites of the American Heart Association -- www.americanheart.org and the ACC -- www.acc.org. A summary of recommendations will be published in the Aug. 31 issue of Circulation: Journal of the American Heart Association. The full update will appear in the September issue of the Journal of the American College of Cardiology.
"This marks the first time we've updated guidelines using the Internet," says. Thomas J. Ryan, M.D., of Boston University Medical Center, chair of the joint ACC and American Heart Association committee responsible for the new guidelines. "We wanted to publish the new recommendations as quickly as possible because of the importance of this new information. Instead of rewriting the full document periodically," explains Ryan, "we have committed to reviewing guidelines every two years to evaluate the need for new recommendations. In the area of heart attack management, the pace of new knowledge drove our decision to reevaluate available diagnostic and treatment possibilities."
The version on the Internet allows readers to quickly find changes in the guidelines. Text that has been changed is identified by strikeout (strikeout) and new text by shading (shading). Some of the most significant highlights of the new guidelines are:
- The previous guidelines recognized that clot-dissolving drugs were not
effective in patients with unstable angina or a type of heart attack known as a
non-ST-segment elevation heart attack. This type of heart attack may seem low
risk at first, but, over a period of two years or so, it can be as life
threatening as other kinds of heart attacks. The new guidelines indicate that
newer classes of medicines -- glycoprotein IIb/IIIa inhibitors (platelet receptor
blockers, sometimes called 'super aspirins') and low molecular -- weight heparins
(anticlotting drugs) -- are now proven to be beneficial in these patients.
- The updated guidelines maintain the previous position that angioplasty
and clot dissolvers are equally effective in restoring blood flow, called
reperfusion, for heart attack patients in certain settings, such as in community
hospitals. However, the update goes further to recommend angioplasty as the
optimal therapy when patients are treated in a certain time frame and where
surgical back up is available. The 1996 document as well as the update also cite
the skill level of the physician and the procedural volume of the institution as
critical elements of the decision to perform angioplasty.
- Bypass surgery or angioplasty are the preferred treatments for patients
who are in cardiogenic shock and under 75 years of age. (Cardiogenic shock, in
which the heart cannot pump enough blood to the rest of the body, is the most
severe complication of heart attacks and is the number one cause of death among
heart attack patients who reach the hospital. Before the findings of a new
trial, known as SHOCK, were presented at the March 1999 ACC Annual Scientific
Session, data did not support the use of aggressive therapy in these patients.
This trial will be published in the New England Journal of Medicine on Aug. 26.)
- Hormone replacement therapy (HRT) for women should not be initiated
after a heart attack, but it may be continued in women who were already on HRT
before their heart attack.
- The intravenous administration of glucose, insulin, and potassium (GIK)
may be valuable in the treatment of heart attacks, particularly in the
developing world.
- The dose of standard heparin (an anticlotting agent) should be lowered
when used with fibrinolytic agents, which are clot-dissolving drugs such as TPA
and streptokinase.