Timing is all: Therapy within 30 minutes ideal
Timing is all: Therapy within 30 minutes ideal
ED staff must act rapidly
Much of the medical-legal activity surrounding use of thrombolytics is focused on the timing of administration. No recognized standard exists for in-hospital thrombolytic administration for acute myocardial infarction (AMI), but the National Heart Attack Alert Program (NHAAP) Coordinating Committee, part of the National Heart, Lung, and Blood Institute in Rockville, MD, has recommended that eligible patients receive treatment within 30 minutes of arrival at a hospital.
That ideal has been labeled the "door-to-needle" time and is a recommendation, not a reality. Patients who present to the emergency department (ED) early give staff a special opportunity and responsibility to act rapidly.
The key to many thrombolytic-related malpractice lawsuits is an allegation of delay in administration, resulting in myocardial injury. In the past, the impact of a reperfusion delay on infarction has been difficult to prove.
However, a growing body of research has found a positive relationship between symptom duration before therapy and final infarction size, turning that around. Each 30-minute increase in symptom duration before thrombolytic therapy is associated with an increase in infarction size. It has been established that there is typically no additional myocardial injury associated with delay beyond the sixth hour.
Onus is on ED staff
The delivery of thrombolytic therapy in the ED is the key to avoiding expensive malpractice suits. Significant strides have been made recently in meeting set parameters, and door-to-needle times at various institutions range from 30 to 90 minutes. Although therapy within a 12-hour window is widely accepted, it’s clear that most benefit comes from treatment within the first few hours of symptoms.1,2
To move a step closer, treatment within the first hour or half-hour of symptoms confers an extraordinary benefit. There is modest but significant benefit for patients whose door-to-needle time for thrombolysis is six-to-12 hours after the onset of symptoms.
Whether any benefit exists in treatment beyond 12 hours is the subject of current research. Ongoing research may result in modification of that recommendation, but no research currently shows any benefit for administering the drugs after 12 hours.
Initiatives are under way at cardiac centers across the country to help patients recognize the symptoms of a heart attack sooner so they don’t delay getting to EDs for treatment.
"The whole point is to reduce delays and expedite time to treatment," says Mary Hand, RN, MSPH, coordinator of NHAAP. In 1991, when NHAAP began, the average door-to-needle time was 60 to 70 minutes. Now it is typically 39 minutes.
Early treatment of eligible AMI patients is critical because of the dramatic relationship between the onset of symptoms to coronary artery reperfusion and ultimate outcome. Pooled data from 42 randomized trials comparing thrombolytic therapy with placebo or conservative treatment 44,346 AMI patients and 4692 deaths convincingly demonstrates the strong relationship between time to treatment and the risk of cardiac rupture and death.3+
Hand says the four "D" time points critical in the thrombolytic process are as follows:
1. Door.
From the moment a patient enters the ED, protocols should be in place to assess the condition rapidly. EDs should have an explicit list of chief complaints that require immediate evaluation by a triage nurse. (See Assess AMI Stat box, p. 102.)
2. Data.
An electrocardiogram (EKG) should be obtained on potential heart attack patients within five minutes of it’s order.
3. Decision.
All hospital medical staff responsible for treating AMI patients should share in developing guidelines for initiating thrombolytic therapy.
4. Drug.
ED physicians should delegate authority to order thrombolytic therapy without having to obtain prior consultation.
[Free copies of the National Heart Attack Alert Program recommendations can be ordered from the National Heart, Lung, and Blood Institute Information Center, P.O. Box 30105, Bethesda, MD 20824-0105. Telephone: (301) 251-1222. Fax: (301) 251-1223.]
Reference
1. LATE Study Group. Late assessment of thrombolytic efficacy (LATE) study with alteplase 6-24 hours after onset of acute myocardial infarction. Lancet 1993; 342:759-766.
2. EMERAS (Estudio Multicentrico Estreptoquinasa Republicas de America del Sur) Collaborative Group. Randomized trial of late thrombolysis in patients with suspected acute myocardial infarction. Lancet 1993; 342A:767-772.
3. Honan HM, et al. Cardiac rupture, mortality and the timing of thrombolytic therapy: A meta-analysis. J Am Coll Cardiol 1990; 16:359-367.
Suggested reading
The National Heart Attack Alert Program Coordinating Committee 60 Minutes to Treatment Working Group. Emergency department: Rapid identification and treatment of patients with acute myocardial infarction. Ann Emerg Med 1994; 23:311-329.
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