Preliminary results from the ASSENT-4 PCI ( Assessment of the Safety and Efficacy of a New Treatment Strategy for Acute Myocardial Infarction-4 Percutaneous Coronary Intervention ) study showed that mechanical reperfusion was not improved when patients were given full dose fibrinolysis before primary PCI.
Clinical outcomes were worse for patients who received combined pharmaco-mechanical reperfusion compared to those who received PCI alone.
The aim of the study was to determine if immediate fibrinolysis prior to delayed mechanical intervention would improve clinical outcomes.
Researchers randomised 4,000 patients from 24 centres with large acute myocardial infarction ( AMI ) for whom PCI was the planned reperfusion option to one of two groups.
The first group received a full-dose, single bolus of Tenecteplase( TNKase, Metalyse ) plus a single bolus of un-fractionated heparin followed by PCI between one and three hours.
The second group received un-fractionated heparin and PCI.
After 30 days, six per cent of people in the Tenecteplase plus PCI group had died, compared with 3.8 per cent in the PCI group (p=0.04).
Enrolment in the study was suspended on 22 April 2005, because the mortality rate in the PCI alone arm was far lower than expected.
William Wijns from Aalst, Belgium, said that one possible explanation for differences between the two groups was insufficient platelet inhibition.
This might offer an explanation for the lower than expected TIMI 3 flow rates prior to PCI, as well as the increased rate of peri-procedural ischaemic complications in the PCI plus thrombolysis group.
Source: European Society of Cardiology ( ESC ) Congress, 2005