Related Experiment Video
Updated: Aug 21, 2026
Prehospital Thrombolysis: A Manual from Berlin
Published on: November 27, 2013
Late thrombolytic therapy: mechanism of benefit and potential risk among patients treated beyond 6 hours
1Thrombosis Research Center, University of Massachusetts Medical School, Worcester 01655.
Insights
Delayed thrombolytic therapy, even beyond 12 hours from symptom onset, can reduce mortality in myocardial infarction patients. Further research is needed to optimize its use, especially for those presenting within 6 hours.
Area of Science:
- Cardiology
- Emergency Medicine
Background:
- Thrombolytic therapy is a primary treatment for myocardial infarction (MI), especially within 6 hours of symptom onset.
- Prompt treatment maximizes benefits, but the role of delayed thrombolysis is under investigation.
Purpose of the Study:
- To evaluate the efficacy and potential benefits of delayed thrombolytic therapy in myocardial infarction.
- To explore the mechanisms and risks associated with thrombolytic therapy administered beyond the traditional 6-hour window.
Main Methods:
- A comprehensive review of English-language literature was performed using MEDLINE, with references dating back to 1912.
- Analysis included findings from nonrandomized clinical studies and the randomized Late Assessment of Thrombolytic therapy Efficacy (LATE) study.
Main Results:
- Evidence suggests thrombolytic therapy may be beneficial up to 12 hours post-symptom onset.
- Potential benefits include myocardial salvage, reduced infarct expansion, improved healing, and decreased ventricular irritability.
- Risks such as myocardial rupture and thromboembolism increase with treatment delay.
Conclusions:
- Delayed thrombolysis, up to and potentially beyond 12 hours in specific patient groups, is associated with reduced mortality.
- Despite evidence, many eligible patients do not receive timely thrombolytic therapy.
- Further research, including the Benefits of Late Thrombolysis (BOLT) study, is crucial to refine treatment protocols.
Background:
Thrombolytic therapy is the treatment of choice for many patients with myocardial infarction, particularly those presenting to the hospital within 6 hours from symptom onset. Although prompt treatment promises to provide the greatest overall benefit, delayed thrombolysis (possibly beyond a time when myocardial salvage is achieved) may also have a role in current clinical practice.
Methods:
A review of the English-language literature was conducted by MEDLINE search. Pertinent references were found as far back as 1912.
Results:
Results of several nonrandomized clinical studies and one recently completed randomized study (the Late Assessment of Thrombolytic therapy Efficacy [LATE]) suggest that thrombolytic therapy may be beneficial up to 12 hours from the onset of symptoms. The mechanisms of benefit are poorly defined, but they may include myocardial salvage, reduced early infarct zone expansion, improved healing, and decreased ventricular irritability. These mechanisms are not necessarily exclusive of one another. An increased risk of myocardial rupture and thromboembolism may be incurred, limiting the usefulness of treatment with further delay.
Conclusions:
Delayed thrombolysis (up to and possibly beyond 12 hours from symptom onset in certain patient subgroups) reduces patient mortality. Despite increasing support, however, many patients, even those seeking medical treatment within 6 hours, are not being given thrombolytic therapy. Further investigation into this area must be undertaken. The Benefits of Late Thrombolysis (BOLT) study should provide much needed information.
Related Concept Videos
01:30Anticoagulant Drugs: Low-Molecular-Weight Heparins
01:16Clot Retraction and Fibrinolysis
01:30Acute Coronary Syndrome I: Introduction
01:29Venous Thrombosis III: Interprofessional Care
01:29Pulmonary Embolism II: Diagnostic Studies and Interprofessional Care
01:15Ischemic Stroke ll: Pathophysiology