Use of thrombolytic treatment in patients with acute myocardial infarction in Spain.: Observations from the PRIAMHO study

Introduction and objectives. Scarce information is actually available in our country regarding the use of thrombolytic treatment in patients with acute myocardial infarction and how consistently the recommendations of the clinical guidelines are being implemented. Methods. Cohort study with one year follow-up of patients with acute myocardial infarction admitted in 24 Spanish hospitals in 1995. Differences in clinical characteristics and prognosis from patients treated with or without thrombolysis were compared. Results. 2,191 of the 5,242 patients (42%) admitted with an acute myocardial infarction received thrombolytic therapy (range: 23%-63%). Reasons for exclusion in the rest were the absence of ST segment elevation (35%), contraindications (16%), prehospital delay >12 h (35%), and other causes (15%). Thrombolysis treated patients were at lower risk in general because they had shorter prehospital delays and were younger, more likely to be male, less frequently diabetic, with less prior history of angina or infarction. The average delay in administering therapy was of 3 hours while the average in-hospital delay was 50 minutes and depended only on the hospital where patients where admitted, as it was shorter in small centers. t-PA was administered in 49% of patients, streptoquinase in 46% and other drugs in 5%. Although t-PA was given more often to younger patients, smokers, anterior and Q-wave infarctions, and to patients with shorter prehospital delays, the determinant factor was the admission hospital with a frequency ranging from 9% to 96%. Patients not treated with thrombolytics had more complications during the acute phase, and required more invasive procedures. They also had a higher mortality at 28 days (17% vs. 10%, p < 0.0001) and at one-year follow-up (27% vs. 15%, p < 0.0001). Furthermore, a correlation was observed between mortality and delay of treatment application. In multivariate analysis, thrombolytic treatment was an independent predictor of survival at one year, with an odds ratio for mortality of 0.8 (95% CI: 0.66-0.96). Conclusion. Thrombolytic therapy in Spain does not yet conform to the recommendations of the actual guidelines for the treatment of patients with acute myocardial infarction because it is underused, especially in high-risk patients, the prehospital and in-hospital delays are too long, and a huge variability exists between hospitals in the frequency and delays of administration and selection of the drug that are not sufficiently explained by the characteristics of the patients. In spite of this, mortality of treated patients was 20% lower in comparison to the nontreated patients, after adjusting for the other clinical factors with demonstrated prognostic value.