Comparison of Tissue Perfusion Measured by ST Segment Resolution between Thrombolysis and Primary Stenting in Acute ST Elevation Myocardial Infarction

ABSTRACT

BACKGROUND AND OBJECTIVES: The primary objective of reperfusion therapy in the acute ST elevation myocardial infarction (STEMI) is the recovery of myocardial perfusion in infarct tissue, as well as the restoration of epicardial blood flow. ST segment resolution on the ECG is an index, which represents adequate myocardial tissue perfusion following treatment. SUBJECTS AND METHODS: Patients with acute STEMI, arriving within 12 hours of the onset of symptom underwent either thrombolysis (n=40) or primary stenting (n=51) were used for this study. ST segments on the ECG were measured with hand-held electronic callipers and the results were analysed by a single observer. RESULTS: Thrombolysis therapy was started earlier than primary stenting, although this was not statistically significant (311+/-171 minutes vs 399+/-251 minutes, p=0.61). After treatment, thrombolysis achieved a higher rate of complete ST segment resolution (>or=70%) compared to primary stenting (20/40;50.0% vs 13/51;25.4%, p=0.016). However, when the data was corrected for time, the difference between the two modalities was not significant (p=0.119). ST segment resolution varied significantly (p=0.026) according to treatment time, regardless of treatment modality. At the 6 month follow up, patients with complete ST segment resolution had a lower rate of major cardiac event (2.1% vs 13.8% p=0.094). CONCLUSION: In this study, thrombolysis achieved a higher rate of complete ST resolution compared with primary stenting in acute STEMI. By ad hoc analysis, this result was attributed to the difference in treatment time between the two groups, suggesting successful tissue reperfusion in acute STEMI is determined primarily by the rapidity, rather than the type, of treatment.