Reasonable "door-to-needle" time for thrombolytic therapy

Canadian Medical Association Journal 1996; 155: 11-20


The recent article "Recommendations for ensuring early thrombolytic therapy for acute myocardial infarction" (CMAJ 1996; 154: 483-487 [full text / résumé], by the Heart and Stroke Foundation of Canada, the Canadian Cardiovascular Society and the Canadian Association of Emergency Physicians, for the Emergency Cardiac Care Coalition) and the accompanying editorial "Initiating thrombolytic therapy for acute myocardial infarction: Whose job is it anyway?" (CMAJ 1996; 154: 509-511 [full text / résumé], by Drs. Eric Letovsky and Tim Allen) focus on practical steps to reduce the rates of illness and death associated with acute myocardial infarction (AMI). Most of the recommendations are thoughtful and, if followed, will result in better care for patients with AMI.

However, I object strongly to one of the recommendations. The authors believe that "thrombolytic therapy can, and should, be administered to a patient with AMI within 30 minutes of arrival to hospital." The editorial makes a similar statement. I find these statements surprising and worrisome, especially since they are made by respected, practising emergency physicians. A 30-minute "door-to-needle time" may be more than reasonable under ideal conditions in patients with uncomplicated AMI. Such a time is very unreasonable for a substantial number of patients with more complex problems, who are seen in crowded emergency departments. Although a multitude of clinical trials has shown the important relation between time to thrombolytic therapy and death rates, I am not aware of any trial in which the standard of care was a door-to-needle time of 30 minutes. Several clinical trials involved a time of 60 to 90 minutes,[1-4] and one study involved a median time of 50 minutes.[5] To dogmatically adopt 30 minutes as the time interval during which all eligible patients are to receive thrombolytic therapy may well result in as many as half the patients receiving less than the recommended care. A more reasonable approach would be to try to treat all patients with uncomplicated AMI within half an hour and all other patients within an hour.

I sympathize with the intent of the recommendations; however, setting unrealistic goals for emergency physicians and nurses will only compound our frustration in being unable to improve the care of these patients and will expose us all to unnecessary litigation.

Anton F. Grunfeld, MD, FRCPC
Department of Emergency Medicine
Vancouver Hospital and Health Sciences Centre
Vancouver, BC


  1. Kereiakes DJ, Weaver WD, Anderson JL et al: Time delays in the diagnosis and treatment of acute myocardial infarction: a tale of eight cities. Report from the Pre-Hospital Study Group and the Cincinnati Heart Project. Am Heart J 1990; 120: 773-780
  2. Sharkey SE, Brunette DD, Ruiz E et al: An analysis of time delays preceding thrombolysis for acute myocardial infarction. JAMA 1989; 262: 3171-3174
  3. Kline EM, Smith DD, Martin JS et al: In-hospital treatment delays in patients treated with thrombolytic therapy: a report of the GUSTO Time to Treatment Substudy. [abstract] Circulation l992; 86 (4 suppl 1): 1-702
  4. Moses HW, Bartolozzi JJ, Koester DL et al: Reducing delay in the emergency room in the administration of thrombolytic therapy for myocardial infarction associated with ST segment elevation. Am J Cardiol 1991; 68: 251-253
  5. Gonzales ER, Jones LA, Ornato JP et al (Virginia Thrombolytic Study Group): Hospital delays and problems with thrombolytic administration in patients receiving thrombolytic therapy: a multicenter prospective assessment. Ann Emerg Med 1992; 21: 1215-1221

[Two of the authors respond:]

The Emergency Cardiac Care Coalition agreed to recommend a 30-minute door-to-needle time only after considerable reflection, discussion and reference to what has been proven possible in the real world. Abundant evidence makes it clear that the earlier thrombolytic therapy is administered, the greater the benefit. Since emergency departments cannot directly affect prehospital delays, we must minimize in-hospital delay in order to provide optimal care.

Several members of the coalition are practising emergency physicians, nurses and other health care professionals with experience in busy urban teaching hospitals, as well as in sparsely staffed rural hospitals, so we are acutely aware that a door-to- needle time of 30 minutes is difficult to achieve and cannot be achieved simply through good intentions.

In reviewing the literature, we identified factors that produce delay as well as protocols and policies that minimize delay. It is correct, as Dr. Grunfeld states, that departments that do not specifically address and monitor thrombolytic therapy times do not reach the 30-minute goal. But several departments have addressed the causes of delay and found ways to overcome it to meet the 30-minute target. MacCallum and colleagues,[l] after instituting policies to minimize delay and monitor performance, reported a median door-to-needle time of 17 minutes for 50 consecutive patients. In a Seattle study, prehospital identification of eligible patients reduced the mean hospital treatment time from 60 to 20 minutes.[2] In a rural community hospital in Pennsylvania, the introduction of a prehospital electrocardiogram protocol decreased hospital treatment times from a mean of 51 minutes to a mean of 22 minutes.[3] Closer to home, physicians and nurses at the Scarborough Centenary Hospital, a busy urban hospital in Ontario, collaborated to reduce time to thrombolysis from 72 to 29 minutes.[4] These and other studies have shown that the causes of delay can be identified and successfully addressed. In the United States, the National Heart Attack Alert Program undertook an intensive review of delay and its causes, and adopted 30 minutes as a realistic goal for the administration of thrombolytic therapy for patients with a clear diagnosis of AMI.[5]

We believe that 30 minutes is a reasonable and realistic goal, which can be achieved for most patients. If the goal of 30 minutes cannot be achieved among some patients, there should be adequate reasons for the additional time. The fact that an emergency department is busy or crowded should not excuse the staff from providing prompt care.

We emphasize that most hospital delay is caused not by patient factors but by hospital factors. If hospitals set up a system to ensure that patients with a clear diagnosis of AMI can be treated within 30 minutes, then patients in whom the diagnosis is less clear will also benefit.

Michael Shuster, MD, DABEM, FRCPC
Emergency Cardiac Care Coalition
Heart and Stroke Foundation of Canada
Emergency medicine
Mineral Springs Hospital
Banff, Alta.

Garth Dickinson, MD, FRCPC
Canadian Association of Emergency Physicians
Assistant professor
Division of Emergency Medicine
University of Ottawa
Ottawa, Ont.


  1. MacCallum AG, Stafford PJ, Jones C et al: Reduction in hospital time to thrombolytic therapy by audit of policy guidelines. Eur Heart J 1990; 11 (suppl F): 48-52
  2. Weaver WD, Cerqueira M, Hallstrom AP et al (for the Myocardial Infarction Triage and Intervention Project Group): Prehospital-initiated vs hospital-initiated thrombolytic therapy: the Myocardial Infarction Triage and Intervention Trial. JAMA 1993; 270: 1211-1216
  3. Foster DB, Dufendach JH, Barkdoll CM et al: Prehospital recognition of AMI using independent nurse/paramedic 12 lead ECG evaluation: impact on in-hospital times to thrombolysis in a rural community hospital. Am J Emerg Med 1994; 12: 25-31
  4. Heart-felt change: improving the care of acute myocardial infarction patients. Informed 1996; 2 (2): 11-12
  5. 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

| CMAJ July 1, 1996 (vol 155, no 1) |