Key result
Late reperfusion therapy (>6 hours) for acute myocardial infarction was associated with higher rates of infarct-related vessel occlusion (41% vs 17%; RR 2.50) and recurrent MI (27% vs 9%; RR 2.94).
Why the study?
Does late reperfusion therapy compared with early reperfusion therapy affect infarct-vessel patency and recurrent myocardial infarction in patients with acute myocardial infarction?
Cohort (n=301)
Does late reperfusion therapy compared with early reperfusion therapy affect infarct-vessel patency and recurrent myocardial infarction in patients with acute myocardial infarction?
Late reperfusion therapy (>6 hours) in AMI patients is associated with significantly lower infarct vessel patency and a higher rate of recurrent myocardial infarction compared to early treatment.
May warrant caution with late reperfusion in AMI; leaves open confirmation in randomized trials.
Patency of the infarct-related vessel is associated with a more favorable long-term prognosis after acute myocardial infarction (AMI). High infarct vessel patency is reported for early reperfusion therapy, but data on patency and its possible effect on clinical outcome are less abundant for patients presenting late after the acute event. The aim of this study was to investigate whether time to reperfusion is related to infarct-vessel patency and clinical outcome. This study compares 268 patients who presented with symptoms of AMI within six hours after the onset of symptoms (Early) with 33 patients who had reperfusion therapy for signs of ongoing ischemia more than six hours after the start of chest pain (Late). At follow-up coronary angiography, flow through the infarct-related vessel was assessed according to the thrombolysis in myocardial infarction (TIMI) classification. Vessels were considered occluded if TIMI flow grade 0 or 1 was present. Follow-up angiography was performed in 95% of patients after a mean of forty-eight days. The infarct-related vessel was occluded in 41% of the late-entry patients (13 of 32), and in 17% of those presenting early (44 of 252), (P = 0.01; relative risk [RR]: 2.50; 95% confidence interval [CI]: 1.26 to 6.83). This was associated with a higher rate of recurrent myocardial infarction in late-entry patients: 27% (9 of 33), compared with 9% (25 of 268) in the early group (P = 0.005; RR: 2.94; 95% CI: 1.50 to 5.81). Thus, in the present study, late reperfusion therapy (after six hours) was associated with a higher recurrent myocardial infarction rate and a lower infarct vessel patency rate, compared with early treatment of patients.
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Hof et al. (1997) conducted a cohort in Acute myocardial infarction (n=301). Late reperfusion therapy (>6 hours after symptom onset) vs. Early reperfusion therapy (≤6 hours after symptom onset) was evaluated on Infarct-related vessel occlusion (TIMI flow grade 0 or 1) (RR 2.50, 95% CI 1.26-6.83, p=0.01). Late reperfusion therapy (>6 hours) for acute myocardial infarction was associated with higher rates of infarct-related vessel occlusion (41% vs 17%; RR 2.50) and recurrent MI (27% vs 9%; RR 2.94).
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