Volume 195 - Issue 3
Prehospital thrombolysis for STEMI: a strategy for town and country?
Author: David B Brieger
Med J Aust 2011; 195 (3): 157-158. || doi: 10.5694/j.1326-5377.2011.tb03252.x
Published online: 1 August 2011
Published online: 1 August 2011
To the Editor: A review by Harper and Lefkovits favoured increased use of prehospital thrombolysis (PHT) for the management of ST-elevation myocardial infarction (STEMI).1 The acknowledged importance of early reperfusion and the ready application of PHT make this a sound recommendation for settings that are remote from percutaneous coronary intervention (PCI) centres. However, the recommendation of using PHT for patients presenting within 2 hours of symptom onset in metropolitan areas is more controversial.
Recent enthusiasm for this strategy has been buoyed by the 5-year data from the randomised CAPTIM study that compared PHT with primary PCI.2 This French study, conducted from 1997 to 2000, was prematurely terminated after recruiting 840 of the planned 1200 patients. There was no difference in the primary composite end point at 30 days. A post-hoc analysis subsequently reported that among the 460 patients randomly assigned to PHT or PCI within 2 hours of symptom onset, there was a trend towards lower mortality among those receiving PHT (2.2% [five patients] v 5.7% [13 patients] at 30 days; P = 0.058).3 By 5 years, an additional eight patients receiving PHT and 12 patients receiving primary PCI had died, resulting in a P value of 0.04 for mortality difference.2 This result reflected one component of a composite end point in a post-hoc subgroup analysis from a prematurely terminated, underpowered trial.
Harper and Lefkovits comment that French registry data support the CAPTIM findings. However, data from a more than 10-fold larger Swedish registry do not.4
Important to the successful implementation of PHT is the transport of patients directly to PCI centres where early angiography can be performed if required. However, PCI and fibrinolysis do not make good bedfellows — a lesson learnt through the counterintuitive results of facilitated PCI trials, which showed no benefit and some harm when offering thrombolysis as a prelude to PCI.5,6 This adverse interaction is ameliorated if PCI is deferred for 3 to 24 hours after thrombolysis; however, there is a real risk that early PCI will be overused when STEMI patients arrive rapidly at a staffed PCI facility after receipt of PHT. We need stronger evidence than currently exists to be sure that, in metropolitan settings, the temptation for zealous application of PCI after PHT does not effectively result in over-application of a facilitated PCI strategy, with untoward consequences.
In metropolitan regions, the current focus on reducing delays from onset of symptoms to percutaneous revascularisation should remain. Based on the evidence to date, PHT may be a cost-effective but not clinically superior alternative for reperfusion, and should be encouraged as the strategy of choice in circumstances when logistic or resource constraints limit ready access to primary PCI.
References
- Harper RW, Lefkovits J. Prehospital thrombolysis followed by early angiography and percutaneous coronary intervention where appropriate — an underused strategy for the management of STEMI. Med J Aust 2010; 193: 234-237.
- Bonnefoy E, Steg PG, Boutite F, et al. Comparison of primary angioplasty and pre-hospital fibrinolysis in acute myocardial infarction (CAPTIM) trial: a 5-year follow-up. Eur Heart J 2009: 30: 1598-1606. i1095852
- Steg PG, Bonnefoy E, Chabaud S, et al. Impact of time to treatment on mortality after prehospital fibrinolysis or primary angioplasty: data from the CAPTIM randomized clinical trial. Circulation 2003; 108: 2851-2856. i1095854
- Stenestrand U, Lindbäck J, Wallentin L; RIKS-HIA Registry. Long-term outcome of primary percutaneous coronary intervention vs prehospital and in-hospital thrombolysis for patients with ST-elevation myocardial infarction. JAMA 2006; 296: 1749-1756. i1095856
- Ellis SG, Tendera M, de Belder MA, et al. Facilitated PCI in patients with ST-elevation myocardial infarction. N Engl J Med 2008; 358: 2205-2217. i1095858
- Assessment of the Safety and Efficacy of a New Treatment Strategy with Percutaneous Coronary Intervention (ASSENT-4 PCI) investigators. Primary versus tenecteplase-facilitated percutaneous coronary intervention in patients with ST-segment elevation acute myocardial infarction (ASSENT-4 PCI): randomised trial. Lancet 2006; 367: 569-578. i1095862