Which is better: thrombolysis (treatment with clot busting medication) or primary angioplasty (an invasive procedure for mechanical opening of the blocked artery)? Does it matter if the patient reaches very early to hospital (within 2-3 hours) or reaches late after onset of chest pain?
A number of studies have shown that in early period (within 2-3 hours of onset of chest pain), thrombolysis is as good or even better than primary angioplasty:
- FAST-MI study
- USIC 2000 registry
- CAPTIM trial and its 5 year results
- Vienna registry
- PRAGUE-2 study
- STREAM trial
- DANAMI-2 study Subgroup analysis of this study quoted by arkiaamu also showed clear benefit only in patients who had duration of chest pain > 4 hours.
Thrombolytic therapy (clot busting medicines e.g. tPA, also called fibrinolytics since they lyse fibrin strands of thrombi or clots) has major advantage in ease of administration. They are administered via intravenous route and hence can be give by nurses or paramedical personnel. The drug travels in the blood stream to reach arteries of the heart and lyses the thrombus (clot) there. Thrombolysis treatement can be given in ambulance while patients are being transported to hospitals or even at patient's home to save time. Tenecteplase, a type of thrombolytic therapy, can be given just as a bolus injection and does not even need infusion. Early after onset of heart attack, the thrombus is soft and possibly smaller in size and hence is more easily lysed by thrombolytic agents.
On the other hand, primary angioplasty needs a fully functioning cardiac catheterization laboratory which costs a lot and are available only in tertiary centers. Trained cardiologists and cath lab technician/nursing staff are needed to perform primary angioplasty. The access has to be through high pressure artery rather than simple vein for thrombolysis. The procedure itself is very complex since the coronary arteries of the heart have to be hooked, wires, balloon catheters, thrombo-suction devices and stents have to be passed into them to open the block caused by thrombus. The logistics of availablity are difficult, especially at nights and on weekends. Hence, the costs are also much more with primary angioplasty.
Because of all these reasons, we should not ignore the role of thrombolytic therapy in patients presenting early after onset of chest pain in acute heart attack. For patients presenting late, primary angioplasty has been shown to be more beneficial than thrombolytic treatment, presumably because the thrombus become more extensive and firm with time and is not easily lysed wih thrombolytic agents (http://www.ncbi.nlm.nih.gov/pubmed/12517460).
There are three types of heart attacks: unstable angina pectoris, non-ST-elevation myocardial infarct (NSTEMI) and ST-elevation myocardial infarct (STEMI). Choosing between thrombolysis and angioplasty matters only in the STEMI.
Which is better: thrombolysis (treatment with clot busting medication) or primary angioplasty (an invasive procedure for mechanical opening of the blocked artery)?
If the patient arrives within 2-3 hours to the hospital from the onset of the pain, "drug of choise" is angioplasty. The evidence is overwhelming. The largest study on this topic involves 1572 randomized to either thrombolysis or primary angioplasty. The latter was superior. Footnote includes other smaller studies on this topic.
The primary angioplasty is best to be performed in less than 120 minutes from the pain. After that, superiority over thrombolysis is not clear, as stated in this high quality meta-analysis.
Does it matter if the patient reaches very early to hospital (within 2-3 hours) or reaches late after onset of chest pain?
If paramedics reaches the patient rapidly after the onset of pain and the patient cannot be moved to a hospital capable performing angioplasty in less than 2-3 hours, it is preferable to perform thrombolysis on-site. This has been showed in many studies (1)(2). What is the optimal time cut-off remains to be shown.
Busk M, Maeng M, Rasmussen K ym. The Danish multicentre randomized study of fibrinolytic therapy vs. primary angioplasty in acute myocardial infarction (the DANAMI-2 trial): outcome after 3 years follow-up. Eur Heart J 2008;29(10):1259-66.
Widimsky P, Bilkova D, Penicka M ym. Long-term outcomes of patients with acute myocardial infarction presenting to hospitals without catheterization laboratory and randomized to immediate thrombolysis or interhospital transport for primary percutaneous coronary intervention. Five years' follow-up of the PRAGUE-2 Trial. Eur Heart J 2007;28(6):679-84.
Nunn CM, O'Neill WW, Rothbaum D ym. Long-term outcome after primary angioplasty: report from the primary angioplasty in myocardial infarction (PAMI-I) trial. J Am Coll Cardiol 1999;33(3):640-6.
Zijlstra F, Hoorntje JC, de Boer MJ ym. Long-term benefit of primary angioplasty as compared with thrombolytic therapy for acute myocardial infarction. N Engl J Med 1999;341(19):1413-9.
Bonnefoy E, Lapostolle F, Leizorovicz A ym. Primary angioplasty versus prehospital fibrinolysis in acute myocardial infarction: a randomised study. Lancet 2002;360(9336):825-9.
Bonnefoy E, Steg PG, Boutitie F ym. Comparison of primary angioplasty and pre-hospital fibrinolysis in acute myocardial infarction (CAPTIM) trial: a 5-year follow-up. Eur Heart J 2009;30(13):1598-606.
Keeley EC, Boura JA, Grines CL. Primary angioplasty versus intravenous thrombolytic therapy for acute myocardial infarction: a quantitative review of 23 randomised trials. Lancet 2003;361(9351):13-20.
Svensson L, Aasa M, Dellborg M ym. Comparison of very early treatment with either fibrinolysis or percutaneous coronary intervention facilitated with abciximab with respect to ST recovery and infarct-related artery epicardial flow in patients with acute ST-segment elevation myocardial infarction: the Swedish Early Decision (SWEDES) reperfusion trial. Am Heart J 2006;151(4):798.e1-7.
Many studie claim that primary angioplasty is better than thrombolyis, as short-time mortality and morbidity of angioplasty is significantly lower than with thrombolysis treatment. (1,3) Reaching late after onset of pain generally reduces effectiveness of any treatment. (2)
You may see this table : http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3377579/table/A01tab02/
 Primary angioplasty versus intravenous thrombolysis for acute myocardial infarction. - http://www.ncbi.nlm.nih.gov/pubmed/12917910
 Assessing the effectiveness of primary angioplasty compared with thrombolysis and its relationship to time delay: a Bayesian evidence synthesis. http://www.ncbi.nlm.nih.gov/pubmed/17277350
 Primary Angioplasty and Thrombolysis for the Treatment of Acute ST-Segment Elevated Myocardial Infarction http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3377579/