Objective: To determine demographic and clinical factors associated with delayed thrombolysis in patients with acute myocardial infarction.
Design: A retrospective cohort.
Setting: 37 Minnesota hospitals during the time periods October 1992-July 1993 and July 1995-April 1996.
Patients: We reviewed the medical records of 776 older patients aged 65 or older hospitalized with an admission diagnosis of acute myocardial infarction, suspected acute myocardial infarction, or rule-out acute myocardial infarction, who were treated with a thrombolytic agent.
Measurement: We used multivariate logistic regression models to examine the association between selected study characteristics and time between hospital presentation and administration of thrombolytic treatment. Early thrombolysis was defined as less than 60 minutes after hospital presentation and late thrombolysis as 60+ minutes.
Results: Of 776 study patients, 57.5% (n = 446) received early thrombolysis. Of the remaining 330 patients receiving late treatment, 12.1% (n = 94) were thrombolyzed more than 2 hours after hospital presentation. After controlling for other factors, the odds of delayed thrombolysis among patients aged 75 or older were 1.48 compared with younger individuals (95% CI, 1.17-1.88). The odds of delayed thrombolysis among patients with severe comorbidity were 1.46 (95% CI, 1.10-1.94) compared with individuals without severe comorbidity. Predictors of early thrombolytic treatment included hospital arrival via emergency transport (ORdelay = 0.46; 95% CI, 0.34-0.63) and chest discomfort at admission (ORdelay = 0.40; 95% CI, 0.18-0.86).
Conclusions: The present study indicates that patients of advanced age and with severe comorbidity are more likely to experience delayed thrombolytic treatment after hospital presentation. These are the patients who suffer the highest morbidity from acute myocardial infarction and for whom expeditious treatment may enhance therapeutic benefit.