There’s a revolution in AMI care: Reteplase could save time and lives

New drug gives heart attack patients a shot in the arm

The interventional cardiology staff at the University of Michigan Medical Center in Lansing is using a new thrombolytic on its acute myocardial infarction (AMI) patients and treating them more swiftly than ever before. Reteplase (r-PA, Penzberg, Germany-based Boehringer Mannheim’s Retavase) is the only FDA-approved thrombolytic that can be administered in a simple double-bolus dose. (See story on FDA approval, p. 7.)

"The new drug gives us the opportunity to treat patients rapidly in situations where every minute counts," explains Eva Kline-Rogers, MS, RN, a researcher there. By comparison, t-PA or alteplase (Genentech’s Activase) is administered as an initial bolus followed by a continuous infusion over 90 minutes. The double-bolus administration requires an hour less delivery time and is easier during an AMI emergency situation. Ease of administration translates into other cost advantages as well, such as reduced need for infusion pumps, tubing, and bags.

Door-to-needle time is of utmost importance with these patients. "You want to expedite the start of infusion from the time they hit the door," says Joanne Tolliver, PharmD, director of pharmacy services at Middletown (OH) Regional Hospital. "The lower that time, the less heart damage and morbidity."

And there’s another advantage to using reteplase. "If you transport a patient from the emergency department (ED) to the ICU while he or she is receiving the drug, you need to monitor the patient," says Tolliver. "You need to take all that equipment with you in transport. You can give one bolus of reteplase in the ED, transport the patient, then give the other bolus. It’s just easier."

The upfront cost of reteplase is about the same as that of other thrombolytics. Tolliver says her facility’s average wholesale price from VHA is $2,640. Other sources quoted prices of $2,200 for both reteplase and activase. "There was no cost savings when we changed from activase to reteplase," says Tolliver.

But Tolliver also noted that thrombolytic therapy in general may be in for some cost cutting soon. "There are a couple of new drugs out now in studies. They should hit the market by the end of next year, so the prices of thrombolytics could come down soon."

The Global Use of Strategies to Open Occluded Coronary Arteries (GUSTO III) clinical trial demonstrated the safety and efficacy of reteplase this past fall, and now investigators are exploring strategies to improve the time spent in diagnosis and treatment of AMI. (See related story on the GUSTO III trial, p. 6.) That will allow emergency medical service (EMS) and ED workers to administer reteplase quickly, even in prehospital settings. The quicker any thrombolytic is administered, the less damage to the heart muscle which results in reduced costs — fewer hospital days, fewer recurrent problems, and reduced morbidity rates — because of decreased tissue damage to the heart.

Duke University Medical Center in Durham, NC, was one of 800 hospitals participating in the GUSTO III clinical trial. Deborah D. Smith, RN, a staff nurse in the ED, says, "I haven’t observed signs or symptoms following reteplase administration that were any different from those following administration of other thrombolytic agents, such as t-PA. There’s nothing unusual."

Smith says, "At our institution, people receiving reteplase do so in connection with research studies, and they receive it within the confines of the hospital, not in the ambulance." (See story on prehospital field administration of reteplase, p. 4.) In other parts of the country, thrombolytic therapy is being administered en route to the hospital, but such prehospital administration is somewhat controversial.

"What I, as an ED nurse, like about reteplase is that with t-PA, you have to hang a 90-minute IV drip," says Smith. "You can give reteplase in two two-minute IV boluses 30 minutes apart. The newer drug doesn’t require an additional IV line."

You get by with two instead of three lines

Patients with heart attacks often have trouble perfusing. "It’s sometimes difficult to attach IV lines," continues Smith. "If we can get by with two instead of three lines, that’s a real benefit from a nursing perspective as well as from the perspective of the patient." An infusion of heparin, for example, can be stopped while the nurse gives the reteplase bolus. Then the line is flushed, and the nurse continues the heparin. Thirty minutes later, the second bolus of reteplase is given.

And there’s another benefit: A nurse has to stay at the bedside for the duration of therapy with these agents because patients are at high risk for arrhythmias. "If a patient has an occluded coronary artery opened by a thrombolytic agent, he or she may have a temporary reperfusion arrhythmia or ventricular tachycardia," explains Smith. The nurse’s bedside time is saved when the therapy can be administered in two boluses 30 minutes apart instead of one 90-minute infusion.

"It’s clear to me that if reteplase uses less resources and frees up a nurse, that’s a real benefit," says Smith. Conceptually those advantages exist, but clinical trials have not been run on saved nursing hours or nurse management issues.

"It takes work to switch from one drug to another," she continues. "You have to inservice the staff, and so on. That may be a potential roadblock to the use of reteplase. Even if nurses find reteplase easier to administer, if one lytic agent is not superior to another in other ways, and the cost is the same, institutions may tend to keep the older thrombolytics."

"The physicians are not concerned about a bleed following lytic therapy in these patients," says Esther Perez, a paramedic instructor for Ingham Region Medical Center in Lansing, MI. "We routinely take patients to the cath lab with heparin as well as thrombolytics on board. There’s a slightly higher risk of complications, but the patients are already screened for high-risk factors."

Perez is participating in a study that started in December that is investigating outcomes when percutaneous transluminal coronary angioplasties (PTCA) follow lytic use. "What we’re trying to demonstrate is that giving thrombolytics early, then going to the cath lab can save heart muscle. The lytic opens the vessel immediately, then patency is maintained with stents." (See story on the new-generation stents, p. 9.)

Three groups will be examined

One arm of the study will follow patients who received two prehospital doses of reteplase, then went to standard CCU procedures including the cath lab if necessary. The second arm will involve patients who received one dose of reteplase in the field, then went to immediate PTCA. The third arm will involve patients who don’t receive the lytic therapy and go to immediate catheterization. All three groups will have some heparin on board.

T-PA has a half life of five minutes, so it leaves the system quickly. Reteplase has a half life of 11 to 19 minutes, so 75 minutes after the bolus, it’s out of the system. If after the first bolus, it’s determined the patient needs to go to the cath lab, the second bolus isn’t given. The drug is effectively gone by the time the patient gets to the cath lab.