Super Aspirin Boosts Clot-busting Therapy

	June 1, 1999 - A new heart attack treatment
may help patients for whom current clot-busting 
therapy does not work.
	Adding a drug called abciximab (Reopro) to 
the standard clot-dissolver called alteplase (TPA),
boosts the odds of restoring normal blood flow after
heart attack by 67%, according to a study published
Tuesday. Such drugs break up the clump of blood 
platelets and proteins that shut off blood flow to
a part of the heart, causing heart attack.
	The study (TIMI14) included 888 heart attack
patients at 63 hospitals. All patients got aspirin 
before being given clot buster drugs. The abciximab 
plus reduced-dose-alteplase patients were also given
low-dose or very-low-dose heparin. Four treatment 
groups were studied, all treated within 12 hours of 
heart attack:

1) 100mg accelerated-dose alteplase
2) abciximab 0.25mg/kg bolus plus 12-hour infusion at 
   0.125 mcg/kg/min
3) abciximab plus 20 to 65mg of alteplase
4) 500,000 to 1,500,000 U of streptokinase.
	
	An hour after treatment was started, 72% of 
patients getting both drugs had normal blood flow 
restored in the clogged artery, compared to 43% of those
getting TPA alone. After 90 minutes, the 2-drug group 
had a 77% success rate compared to 62% for those getting
only TPA.
	The double-drug treatment had a success rate 
nearly equal to an artery-clearing procedure called
balloon angioplasty. The TPA-ambicixmab treatment may 
become standard, reserving angioplasty for patients 
with bleeding disorders or other reasons why they should
not take the clot busting drugs.
	The drug combination is more effective because
abciximab targets platelets - sticky, disk-shaped blood
cells that make up a major part of blood clots. TPA 
works on a clot protein called fibrin. By attacking both
clot components, the drugs seem to dissolve it more
completely and quickly.
	TPA has the undesirable effect of activating
platelets, which may explain why some heart attack 
patients develop new clots after the first one dissolves.
Abciximab blocks this process. Aspirin, which is widely
used in heart attack care, also blocks platelet 
activiation but abciximab is more potent, which is why
the drug is often called a "super-aspirin."