Angioplasty vs Drug Therapy
When Time Is Key, Should One Wait For Angioplasty?
What is the problem and what is known about it so far?
Angioplasty, an invasive procedure using a balloon to open up blocked coronary arteries, has been shown to be superior to fibrinolysis, a non-invasive medical approach using chemicals to dissolve clots in heart blood vessels, in the treatment of new-onset heart attacks. This advantage was noted when patients were admitted to specialized hospitals that had the resources on-hand to perform angioplasty. Whether or not the benefit of performing angioplasty is maintained when patients have to be transferred from community hospitals is uncertain.
Why did the researchers do this particular study?
Transportation from a local hospital to a major medical center with angioplasty resources has been considered to be a major limitation on the widespread adoption of primary angioplasty as a first-line treatment for heart attacks. The researchers sought to understand if the delay in treatment posed by transportation would have an effect on a patient's overall outcome.
Who was studied?
This study was conducted in Denmark, involving hospitals that served a significant portion (62 percent) of the Danish population. From December 1997 to October 2001 heart-attack patients from 24 referral hospitals without angioplasty facilities and from 5 invasive-treatment centers with such services were recruited. At the time of the study's conclusion 1129 patients from referral hospitals and 443 patients from invasive-treatment centers had been evaluated.
How was the study done?
The trial consisted of two simultaneously conducted sub-studies, one involving patients drawn from the referral hospitals and the other involving patients from the invasive-treatment centers. Patients from both types of hospitals, upon admission for an acute heart attack, were initially randomized to receive either primary angioplasty or fibrinolysis. Patients were stabilized according to established protocols before receiving either fibrinolysis or angioplasty In the case of a patient requiring transfer a cut-off of 3 hours was established as the maximum amount of time allowed to complete the transfer to an invasive-treatment center. To determine the relative benefit of angioplasty versus fibrinolysis in their study the investigators measured the number of patients who died, suffered another heart attack, or suffered a disabling stroke 30 days following their course of treatment.
What did the researchers find?
Primary angioplasty was found to be superior to fibrinolysis, even when patients were admitted to a local hospital without angioplasty services and were then transported to an invasive-treatment center. The benefit that the researchers found in providing angioplasty was primarily shown by a reduction in the risk of a repeat heart attack; the risks for death and stroke were not significantly affected. The transfer of patients was found to be safe, with nearly all patients requiring transfer arriving at invasive-treatment center within two hours after being randomized for study.
What were the limitations of the study?
This study was designed to specifically minimize any delay in treatment. For example, patients bypassed emergency rooms and were admitted directly to coronary care units. Although the authors contend that their results are broadly applicable to most Western communities, it remains to be seen if the highly coordinated logistics applied in their study could be realistically implemented in the U.S. Even with rapid transfer to a specialized center, the true limitation for a beneficial outcome may be the experience of the team performing the angioplasty at that particular moment.
What are the implications of the study?
In this country transportation of a patient to a specialized treatment center poses significant practical and logistical issues. Fibrinolysis should still be considered for heart attack patients who present to hospitals without angioplasty services within 2 to 3 hours after the onset of symptoms. However, transfer to a specialized center should be strongly considered when the delay posed by transfer will require less than 60 minutes, or when more than 3 hours have elapsed since the onset of symptoms.
Summarized by Stanley Kang, College of Medicine, University of Vermont
Summarized from "A Comparison of Coronary Angioplasty with Fibrinolytic Therapy in Acute Myocardial Infarction". Andersen, H.R. et al. New England Journal of Medicine, August 21, 2003, Volume 349, Number 8, Pages 733-742.
