Participation in thrombolytic trials delays reperfusion therapy in acute myocardial infarction

Shortening the time delay at the beginning of treatment in ST-segment elevation myocardial infarction (STEMI) has proven to be clinically essential. Invasive vs. thrombolytic treatment strategy is currently under investigation, particularly in terms of the time from the onset of symptoms to treatment initiation. It is likely that enrolment to trials in STEMI may paradoxically prolong the time delay to treatment if randomisation procedures are too complex.

To evaluate time to the onset of reperfusion therapy (door-to-thrombolysis time - DtT) in patients randomised to trials (TT) or treated routinely with thrombolytics (Thrx).

We evaluated DtT in a group of 189 consecutive STEMI patients (TT: n = 96; Thrx: n = 93). The inclusion criteria for the analysis were identical in both groups: 1. STEMI diagnosis was given on admission. 2. Patients had no signs of heart failure. 3. Patients did not require any additional therapy prior to thrombolysis (no need for electrical cardioversion or blood pressure lowering). 4. There were no contraindications for immediate reperfusion therapy. The comparison of DtT between evaluated groups was performed. To find out the independent predictors of DtT prolongation, the impact of patients' age, gender, admission time, pre-hospital delay and trial participation has been evaluated in multivariate analysis.

Highly statistically longer mean value of DtT was measured in the entire TT group than in Thrx (41 ± 18 vs. 22 ± 8 min; p 〈 0.001). The difference was also significant for patients who constituted the subgroup of TT who were proposed and refused to participate in trials (37 ± 13 vs. 22 ± 8 min; p 〈 0.01). No differences in DtT were found between groups of patients enrolled to various trials. The participation in TT was found to be the strongest predictor of DtT prolongation over 30 min (OR 13.2; 95% CI 6.1-28.5; p 〈 0.001). The risk of over 30 min DtT prolongation was five times higher if patients were admitted in an early phase of the trial.

1. Participating in trials delays the beginning of reperfusion therapy. 2. This delay may be clinically important, particularly in patients hospitalised in a very early phase of STEMI. 3. The call for reappraisal of informed consent issues and randomisation procedures in the context of simplicity seems to be justified.