By Christian J Terkelsen
Primary percutaneous coronary intervention (PPCI) has proven superior to fibrinolysis in the treatment of patients with ST-elevation myocardial infarction (STEMI), if initiated timely. However, PPCI is not universally available, and many patients are still prioritised for fibrinolysis. In Denmark, PPCI has been implemented as a national reperfusion strategy. How is this possible, and is it wise?
The guidelines state that delay from first medical contact to PPCI (FMC-to-PPCI) should be less than 120 minutes, otherwise fibrinolysis should be initiated. In this recommendation the guidelines do not take into account that fibrinolysis cannot be initiated instantaneously. Unfortunately, there is a general mixing of the terms “FMC-to-PPCI” and “PCI-related delay”. The latter term reflects the extra delay used to perform PPCI instead of administering fibrinolysis, i.e. the anticipated delay from drug administration to balloon-inflation if one chooses PPCI instead of fibrinolysis.
There is evidence to support that even if we spend more than 120 minutes to perform PPCI instead of administering fibrinolysis there will be a benefit from PPCI. Real-life data from Sweden even support a beneficial effect of PPCI if one uses up to extra four hours to perform PPCI instead of administering fibrinolysis. On the other hand, there is no single reference to support the guideline statement that fibrinolysis should be given at any circumstances if “FMC-to-PCI” is performed after 120 minutes. Even though the overall aim should be to keep “FMC-to-PCI” below 120 minutes, which has proven to be associated with lower mortality, PPCI will still be superior to fibrinolysis also at “FMC-to-PCI” over 120 minutes if the PCI-related delay is 120 minutes or less. Therefore, even late PPCI is superior to or comparable to early fibrinolysis.
In Denmark, we have learnt from the DANAMI-2 trial that transfer to PPCI is superior to fibrinolysis when looking at a combined endpoint, and later on it has been confirmed that also when looking at mortality there is a benefit of PPCI compared to fibrinolysis, even if it implies transfer of patients. Notably, during the DANAMI-2 trial, prehospital diagnosis was not implemented, and accordingly field-triage was not implemented either.
In 2003, PPCI was introduced as a national reperfusion strategy in Denmark. To ensure optimal “FMC-to-PPCI”, telemedicine was implemented for prehospital diagnosis and patients were prioritised for field-triage directly to invasive centres for PPCI. At present, we have 450 ambulance vehicles that transmit ECGs from the field to one of 15 telemedicine centres. In larger cities we have ambulance physicians, and when we field-triage patients directly to one of our four invasive centres we order rendezvous with the ambulance physicians so they meet the patient on the way to the centre.
This strategy has resulted in a gradual increase in the number of patients that are re-routed directly to the invasive centres. In a recent publication in Circulation Cardiovascular Intervention we presented 11 years of experience with PPCI in patients with STEMI in Western Denmark.
Currently, 75% of patients who are transported by ambulance vehicles are triaged directly to a PCI-centre, which is associated with one hour earlier initiation of reperfusion, and lower mortality when compared to patients not field-triaged. Our overall aim is to field-triage 90% of patients, which is almost achieved in areas with special focus on prehospital diagnosis and field-triage of patients.
In conclusion, we find this single reperfusion strategy to be ideal in Denmark. The prerequisite is the implementation of prehospital diagnosis and field-triage of patients directly to large-volume PPCI centres running 24/7. This guarantees experienced operators and enables door-to-balloon times below 30 minutes.