Update on goals for fibrinolytic therapy
You’ll need to become accustomed to some new terminology: The term "fibrinolytic" is now used instead of "thrombolytic," according to new guidelines published by the Dallas-based American Heart Association (AHA).
Fibrinolytic therapy has been adopted as a standard of care, and has shown a reduction in mortality for eligible patients with acute coronary syndromes or ischemic stroke, notes Darlene Bradley, RN, MSN, MAOM, CCRN, CEN, director of emergency/trauma services at UCI Medical Center at University of California-Irvine.
"If the thrombus occludes the coronary vessels for a prolonged period of time, the result may be a Q-wave myocardial infarction," she explains. "The clot formation is made of thrombin and fibrin. In this case, fibrinolytic therapy is beneficial."
Fibrinolytics are a key part of management for patients with acute coronary syndromes, says Mary Fran Hazinski, RN, MSN, FAAN, senior science editor for the AHA’s emergency cardiovascular care programs and clinical specialist in the division of trauma in the departments of surgery and pediatrics at Vanderbilt University Medical Center in Nashville, TN. "We now realize that acute coronary ischemia actually starts when there is rupture of a lipid laden plaque. There is an inflammatory component in the vessel and plaque ruptures, and that attracts additional platelets."
Fibrinogen cross-links the platelets, and a partially occluding thrombus can form and cause ischemia, says Hazinski. "At that point, the thrombus is sensitive to antiplatelet agents or new glycoprotein IIb/IIIa receptor inhibitors or aspirin," she explains. "The thrombus may enlarge and throw off microemboli to distal vessels, causing myocardial infarction [MI]."
If the thrombus occludes a coronary vessel for a long period, an MI can occur, Hazinski explains.
The guidelines also recommend use of fibrinolytics in patients with acute ischemic stroke, notes Hazinski. "If patients receive this therapy within three hours of the onset of stroke symptoms, their recovery can be much better," she says.
Fibrinolytics can minimize neurologic damage in patients with stroke and myocardial damage in patients with MI, but the key is that this therapy must be given within a few hours of onset of symptoms, Hazinski stresses. "That’s why it’s imperative that the lay public recognize symptoms and get to a medical center capable of providing advanced therapy as soon as possible," she says.
ED nurses play a critical role in increasing the likelihood that these patients will be eligible for this therapy by identifying patients at triage and facilitating rapid evaluation with appropriate diagnostics, adds Hazinski. Patients with MIs are triaged according to their 12-lead electrocardiogram results, she says. "The ED nurse needs to ensure that it’s obtained and interpreted to help classify the patient for therapy," Hazinski explains.
Currently, only about 7% of stroke patients are evaluated in a time period that would enable them to receive thrombolytic therapy, says Hazinski. "This concern also applies to patients with MIs," she adds. "We have a lot of work to do to reduce the time to arrival in the ED and triage and [evaluation] with therapy."
Fibrinolytic therapy for ST elevation MI is the standard of care, notes John M. Field, MD, FACC, FACEP, associate professor of medicine and surgery at Pennsylvania State University College of Medicine in Hershey, and ACLS science editor at AHA. "Percutaneous coronary intervention-angioplasty/stent is an acceptable alternative," he says. "There is a 30-minute goal for door-to-drug, and a two-hour goal for door-to-balloon."
In patients younger than age 75 who are in shock or in heart failure with large MI, triaging to a facility capable of performing percutaneous coronary intervention is Class I (highest recommendation) when available, says Field.
Prehospital electrocardiograms are recommended (Class I) when the receiving hospital is notified and acute MI is identified, says Field. "Fibrinolytic therapy for stroke candidates who qualify has been moved from Class IIA recommendation to Class I, when a computerized tomography scan and drug can be administered within three hours of symptom onset."
The guidelines state that intravenous recombinant tissue plasminogen activator (rTPA) improves neurological outcome when administered within three hours of stroke onset in patients who meet fibrinolytic therapy criteria, says Rebecca L. Stark-Johnson, CRNA, APNP, anesthesia manager at Fort Atkinson (WI) Memorial Health Services, and a regional faculty instructor for the AHA’s ACLS Program. "The urgency should equal that of an acute MI with ST segment elevation," she stresses.
The use of rTPA in patients with symptoms of three to six hours is under investigation, notes Stark-Johnson. "Prourokinase has been found to improve neurologic outcome in patients treated within three
to six hours in one study," she reports.1
Emergency medical services systems should implement a prehospital stroke protocol to rapidly identify patients who may benefit from fibrinolytic treatment, she recommends.
Reference
1. Del Zoppo GJ, Higashida RT, Furlan AJ, et al. Prolyse in Acute Cerebral Thromboembolism (PROACT) Investigators. PROACT: A phase II randomized trial of recombinant Prourokinase by direct arterial delivery in acute middle cerebral artery stroke. Stroke 1998; 29:4-11.
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