The purpose of this study was to determine whether the implementation of therapeutic guidelines effectively improves in-hospital mortality after an acute ST-elevation myocardial infarction (STEMI) in a metropolitan area, in this case Vienna, Austria.
This was based on (1) the then-recommended time intervals, and (2) the varying clinical status of individuals presenting with myocardial infarction. For this purpose, uniformity among catheterisation laboratories was created by the implementation of a central triage network via the Viennese Ambulance System (VAS) in conjunction with recommendations to initiate TT, either in-hospital or before arrival at the hospital, if PPCI could not be offered in a timely fashion, particularly in patients who had experienced symptoms <2 hours. At the same time, a prospective registry was established for control and quality assurance purposes.
In 2002, Vienna, a city with 1.8 million inhabitants, had only 1 catheterisation laboratory (at the Department of Cardiology, University of Vienna) which offered a 24-hour PPCI service on a routine basis (on-call) for patients with acute STEMI. This situation was profoundly reorganised by the implementation of (1) central triage for STEMI patients by the Viennese Ambulance System (VAS); (2) a second catheterisation laboratory open at night (Monday to Friday) by use of a rotation principle between 4 non-academic hospitals (on weekends [Friday afternoon to Monday morning], only 1 catheterisation centre was active during this preliminary network); and (3) pre-hospital or in-hospital TT if acute PPCI was unlikely to be offered within the recommended time intervals.
CHANGES IN REPERFUSION STRATEGIES
Implementation of guidelines resulted in an increased number of patients treated with one of the two reperfusion strategies (from 66% to 86.7%). Accordingly, the proportion of patients not receiving reperfusion therapy dropped from 34% to 13.4%. Management of patients via PPCI increased from 16% to almost 60%, whereas the use of TT decreased from 50% to 26.7% in the participating centres.
TREATMENT STRATEGIES SEGMENTED BY TIME-TO-TREATMENT
Adapted from Kalla et al. Circulation 2006; 113: 2398–2405.
PCI could only be offered to 14.6% of patients within the first 2 hours after symptom onset, whereas thrombolysis was offered to 50.5% of patients within the first 2 hours after symptom onset.
In-hospital mortality rates were lowest in patients treated within 2 hours of symptom onset. Although the differences were not statistically significant, there was a trend in favour of thrombolysis over PCI (PCI 7.8%, thrombolysis 5.1%; p=0.37). However, as time from symptom onset increased, there appeared to be an increasing survival benefit with PCI over thrombolysis.
- Implementation of guidelines for the treatment of acute STEMI by the organisation of a cooperating network within a large metropolitan area was associated with a significant improvement in clinical outcomes.
- Kalla et al. Circulation 2006; 113: 2398–2405.