Management of prehospital thrombolytic therapy in ST-segment elevation acute coronary syndrome (<12 hours)

Acute myocardial infarction (AMI) is the prototype of a real emergency, and both efficacy and speed are necessary for effective management. The advent of thrombolysis therapy has transformed the care of these patients. In fact, the most frequent complication of AMI is sudden death which still occurs within the first hour after symptom onset. Thrombolytic therapy has been shown to reduce early and long term mortality about 20%. The mortality gain is dependent on the delay time of early reperfusion. A large number of studies have shown that this relationship is best described as exponential: in the first 1 to 2 hours after the onset of chest pain, the benefit of thrombolysis is greater. Reducing the time to thrombolysis must therefore be the main objective of prehospital treatment of AMI. In the last 10 years, a large number of strategies to reduce the time to reperfusion have been evaluated, including initiation of thrombolytic therapy prior to arrival to hospital. In France, prehospital emergency medicine is an integral part of the medical care system. The SAMU is a hospital department whose function is to centralize emergency medical calls and organise an appropriate response with the intention of ensuring the shortest delay between the initial call and the appropriate treatment. In the event of an emergency medical call concerning chest pain, the medical dispatcher of SAMU may decide to send a MICU (mobile intensive care unit). If a diagnosis of AMI is confirmed, clinical ECG criteria, prehospital thrombolysis is currently seen as the best treatment strategy. The SAMU experience has proven that prehospital thrombolysis is both safe and effective. During the last ten years to fifteen years the field of reperfusion during acute myocardial infarction was a real battlefield between the proponents of thrombolysis and those of primary percutaneous interventions. Nowadays there is a growing number of physicians who will consider that the best way forward is not to oppose these two effective methods but to find the most appropriate niche for each or even better to combine them to achieve reperfusion. In this respect, the concept of facilitated percutaneous intervention is a very attractive one which shows promising results. A large number of studies are now ongoing to demonstrate its efficacy and to help us to choosing the ideal combination of anti-thrombotic agents to be used. That is one of the main interests of the CAPTIM study. French trial comparing prehospital thrombolysis to primary angioplasty. There is no difference between the two strategies in term of primary end points. That could be the real life for acute myocardial infarction. We have to consider in this study the fact than 33% of the patients had a pre hospital thrombolysis followed by a fast angioplasty. The results are impressing: the 30 day mortality in the pre hospital thrombolysis arm is only 3.8%. But if the delay between pain to pre hospital thrombolysis is under 2 hours this 30 day mortality fall down to 2.2%. This is better

Than il all the recent trials published comparing on site thrombolysis to primary angioplasty (DANAM II, C Port, PRAGUE II). These good results in the CAPTIM study when the delay pain to treatment is less than 2 hours include also the occurrence of cardiogenic shock in favour of pre hospital thrombolysis (1.3%). The good strategy in a next future could be the association of pre hospital thrombolysis and angioplasty. In a recent French register (USIC 2000) including all the patients arriving in CICU during a month and regarding the one month mortality this strategy seems to be the best (3.6%). The arrival of TNK-tPA is now changing the general management of prehospital AMI by reducing the time to treatment. This is clearly now the new standard of prehospital treatment. The reduction of UHF dose is recommended and the LWMH is considered as the next step as recently demonstrated in the ASSENT 3 and 3+ trials. Several recent registries have shown than we offer reperfusion to only half of the patients and even more important, when we do not offer it, this is unjustified in nearly half of the cases and these patients , forgotten for reperfusion have all a very poor prognosis. The other major problem is that patients are treated too late mainly because the call the emergency system too late. The are several ways to improve the time to treatment : information of the patients , shortening of the intra-hospital delays by better organisation and finally and perhaps more importantly , pre hospital triage and treatment. The efficacy and safety of the pre hospital strategy is now recognised worldwide. The best strategy for acute myocardial infarction should involve emergency physicians and cardiologist in a real local task-force to join and coordinate their efforts. That is the way to open more arteries earlier, that is to say save myocardium and more lives.