Article

Fast-track Primary Percutaneous Coronary Intervention in Patients with ST-elevation Myocardial Infarction

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In patients with ST-elevation myocardial infarction (STEMI), reperfusion can either be in the form of fibrinolysis or primary percutaneous coronary intervention (PCI). In recent years, several trials have proven the superiority of primary PCI compared with fibrinolysis,1-5 and it is estimated that primary PCI saves an extra 26 lives per 1,000 treated, when compared with fibrinolysis (Table 1).3 The interventional approach has proven superior even among most patients admitted to hospitals without catheterisation laboratory facilities, in these cases, transfer to an interventional hospital is necessary.1,6 Still, the time-dependent prognostic benefit of reperfusion is important to remember.7-10 Every hour of reduction in treatment delay may translate into an extra 15 to 20 lives saved per 1,000 treated (Table 1).10-13 The importance of prompt diagnosis and treatment necessitates that close attention is paid to every step in the procedure from symptom onset to reperfusion of the myocardium.

Optimisation of Patient Delay

Patient delay - time from onset of symptoms until calling for help - is still the major cause of treatment delay - time from onset of symptoms until initiation of reperfusion therapy. However, both American and European studies have shown that patient delay is very difficult to reduce and media campaigns have been unsuccessful.14,15 Although this is the case, people should still be encouraged to call for help as soon as possible after onset of chest discomfort and patients should be informed that contact to the emergency medical system is preferable to seeking primary care.16 Likewise, even though self-transportation results in earlier admission to local hospitals,17 it hampers the possibility of a fast-track re-routing of patients directly to interventional hospitals.

Optimisation of the Pre-hospital Triage

When a patient with chest discomfort calls for help it would be optimal if emergency vehicles were immediately dispatched to the patient, rather than a primary care physician spending time evaluating the patient. On arrival, acquisition of a pre-hospital electrocardiogram (ECG) is mandatory. If emergency vehicles are neither staffed with physicians nor paramedics trained in the establishment of pre-hospital diagnosis, a strategy of transmitting ECGs to a hospital-based physician for further analysis is recommended.18-22

When a diagnosis of STEMI is confirmed, patients should be re-routed to the nearest interventional hospital for primary PCI. In this setting, initial admission to a local hospital has been associated with a 30-50 minute delay before transfer.1 A re-routing strategy, e.g. bypassing the local hospital, would result in a substantial reduction in the cumulated treatment delay (Figure 1).4,5,22-26 A re-routing strategy, however, may imply that patients are transported for longer distances without accompanying physicians. This may require education of ambulance staff to higher level than at present. Alternatively, a strategy of rendezvous is possible, where the ambulance staff request a physician or nurse to meet them on the route to the interventional centre.

Optimisation of Local Hospital Strategy

If patients cannot be referred directly from the scene of the event to the interventional centre, a strategy for immediate transfer from the receiving local hospital should be implemented. It would be optimal, though, if a pre-hospital diagnosis was established. Thus, the local hospital would be alerted and prepared for transfer of the patient. It has also been shown that strict protocols for the treatment and transfer of patients with acute myocardial infarction (AMI), along with practical training of the staff at the receiving hospital can successfully reduce the arrival to departure time.27 A separate strategy should be devised for patients presenting themselves to the local hospital with chest pain, so that diagnosis is made quickly and reliably in order to start treatment and referral at once.23 The number of patients with AMI who make their initial contact to the emergency department of their own volition is relatively small in Europe, but constitutes almost half of the patients in the US.

Optimisation of Interventional Centre Strategy

In large-volume centres with round the clock catheterisation laboratory facilities, it has been documented that a door-to-balloon time of 30- minutes is achievable.1,4,5 This is in contrast to several studies and registries from the US that show door-to-balloon time consistently of 90 minutes or above. Thus, the benefits of large-volume centres are two-fold:

  1. physicians have enough cases to maintain their skills; and
  2. the centres have enough skilful physicians to offer a 24-hour/365-day primary PCI program, which is required to achieve optimal door-to-balloon times.

A recent study28 investigated the cause of delay in door-to-balloon time; and documented that the major difference in delay between top performing cardiology centres and lower performing centres is the time from diagnosis (ECG) to reperfusion. It demonstrated that optimising in-house transfer of patients to the catheterisation laboratory can result in timely reperfusion therapy by angioplasty. The authors recommend that referral from local hospitals should be co-ordinated in order for the interventional centre to be prepared for the procedure, making it possible to accept the patients directly at the cardiac catheterisation laboratory without the unnecessary delay of first admitting patients to the emergency department or coronary care unit. Ideally, the physician at the interventional hospital is available at the time of ambulance arrival. In this setting, it is recommended that the paramedics in the arriving ambulance alert the physician at time of departure from the local hospital or scene of event and when the estimated time to arrival at the interventional hospital is 10-15 minutes. The latter strategy can be made even more sophisticated by installing GPS transmitters on the ambulances in order for the interventional centre to monitor the position of several arriving ambulances continuously.

Conclusion

In the era of primary PCI, a successful reduction in treatment delay may save as many lives as any other adjunctive pharmacological or interventional treatment initiated in the acute phase. Pre-hospital diagnosis and re-routing of patients directly to interventional hospitals combined with a 24- hour/365-day primary PCI facility seems obligate to achieve such a goal.