Will tPA force changes in cardiac care?

Will tPA force changes in cardiac care?

Federal approval of the clot-dissolving drug called tissue plasminogen activator, or tPA--announced just before researchers and clinicians gathered in Anaheim--made a big splash among cardiac physicians and economic analysts aware of the drug's potential market (SN: 11/21/87, p.325). Lauded as superior to current clot-dissolving drugs because of its specificity, tPA binds to and acts on certain proteins in the clot, rather than nonselectively destroying similar proteins also found circulating in the blood. The genetically engineered drug is expected to restore blood flow and thus minimize heart tissue damage in many thousands of heart attack victims. But observers say that tPA's endearing qualities may rattle medicine's approach to cardiac care.

Besides being so specific, tPA dissolves clots rapidly. But it must be administered quickly to be effective. Injection of the drug within six hours of the first symptoms is recommended, and researchers agree the sooner the better. But how, when many people do not realize at first that they are having a heart attack, can the drug be administered immediately? And what about the time it now takes to determine whether a patient in the emergency room has has an attack?

The public and physicians need a "raising of consciousness' regarding heart attacks, says Eugene M. Braunwald of Brigham and Women's Hospital in Boston. Along with this increased knowledge, however, hospital staff will see "a massive augmentation' of frightened patients whose chest pains are not due to a heart attack, predicts Alan M. Ross of George Washington University Hospital in Washington, D.C.

With tPA now available, there may be a need for specially trained emergency-room nurses to identify heart attack victims before the doctor comes, says Braunwald. But researchers suggest that the best therapy approach might be to give tPA before a patient even reaches the hospital. A recent study in West Germany found that important minutes were saved by tPA-injecting, ambulance-riding physicians. "We may have to start making house calls again,' says George A. Beller of the University of Virginia Medical Center in Charlottesville. As Ross says, the "fast conveyor belt' that now takes cardiac patients to the angioplasty room may be slowed by using tPA first. But clinical studies indicate that most tPA-treated patients still will eventually need angioplasty or bypass surgery, says Eric J. Topol of the University of Michigan in Ann Arbor.