Objective: To examine the frequency and determinants of re-infarction after thrombolytic treatment of ST-elevation myocardial infarction (STEMI).
Design: Observational study of national registry.
Setting: Emergency ambulance services and admitting hospitals in England and Wales.
Patients: 35 356 patients with STEMI given thrombolytic treatment in 2005–6.
Main outcome measures: Re-infarction during hospital admission.
Results: For 22 391 patients (63.3%) the presence or absence of re-infarction was recorded, and 1460 (6.5%) had re-infarction. Re-infarction rates with in-hospital treatment were similar for reteplase (6.5%) and tenecteplase (6.4%). When the interval from pre-hospital treatment to hospital arrival was greater than 30 minutes re-infarction rates were 12.5% for reteplase, and 11.4% for tenecteplase. Overall, re-infarction rates were higher after pre-hospital treatment with tenecteplase than reteplase (9.6% vs 6.6%, p = 0.005). After multivariate analysis independent predictors of re-infarction for tenecteplase were pre-hospital treatment, OR 1.44 (95% CI 1.21 to 1.71, p<0.001) and weight in the highest quartile compared to the lowest, OR 1.66 (95% CI 1.19 to 2.31, p = 0.003). For reteplase neither factor predicted re-infarction. Bleeding was less common with pre-hospital treatment—overall 1.8% against 3.1%; intracerebral bleeding 0.4% against 0.7%.
Conclusion: Pre-hospital treatment with tenecteplase was associated with higher re-infarction rates. Longer intervals from pre-hospital treatment to arrival in hospital were associated with high re-infarction rates for both tenecteplase and reteplase. Differences in the use of adjunctive anti-thrombotic therapy in the two treatment environments may underlie the differences in re-infarction rates and bleeding complications observed between pre-hospital and in-hospital thrombolytic treatment.
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Competing interests: CW, JB and TQ have at various times received honoraria for acting as advisers to Boehringer Ingelheim on the early management of acute myocardial infarction and for lecturing at meetings sponsored by Boehringer Ingelheim.
Funding: MINAP receives core funding from the Healthcare Commission and is housed within the National Institute for Clinical Outcomes Research, University College London, London. The research presented here is independent of any influence of the funders of MINAP.
JB is the guarantor of the study.