Primary angioplasty in acute myocardial infarction: differences between referred patients and those treated in hospitals with on-site facilities?

Background: Primary angioplasty for acute myocardial infarction (AMI) can only be performed in a limited number of centers. Therefore, some patients will be referred for this procedure.
Design: We analyzed the data of the prospective observational MITRA trial, which took place at 54 hospitals in southwest Germany, to describe current practices and outcomes in referred patients compared to patients treated on-site.
Results: Out of 491 patients treated with primary angioplasty, 63 (12.8%) were referred. Out of 46 hospitals without facilities to perform primary angioplasty, 29 (63%) never referred patients. Referred patients were less often male (60.3% versus 75.9%; p = 0.013), suffered more often from anterior wall infarction (62.9% versus 45.8%; p = 0.014), and more often had absolute contraindications against thrombolysis (11.1% versus 2.8%; p = 0.006). In-hospital time to treatment was 80 minutes in patients treated on-site compared to 190 minutes in referred patients (p = 0.001). There was a non-significant difference of in-hospital mortality between the two groups (11.1% for referred versus 7.5% on-site; p = 0.319). Referred patients had a higher hospital morbidity as expressed by a higher proportion of post-infarction angina (28.6% versus 4.2%; p = 0.001), a more frequent need for urgent revascularization (43.8% versus 16.4%; p = 0.001) and a higher proportion of advanced heart failure (11.1% versus 4.4%; p = 0.062).
Conclusions: Referral of patients with AMI for primary angioplasty is used only in a minority of hospitals. The referred patients represent a selected, more ill subgroup, resulting in a higher hospital morbidity compared to patients treated on-site. Continuous efforts should be undertaken to decrease the time delay from admission at the initial hospital to the beginning of revascularization.