The Air Primary Angioplasty in Myocardial Infarction Study. - Air PAMI
Does early transfer for primary PTCA of patients with acute myocardial infarction (MI) result in better outcomes when compared with on-site thrombolysis?
The study population included patients with high risk MI (age >70 years, anterior MI, Killip class II/III, heart rate >100 beats/min, or systolic BP <100 mm Hg), who were eligible for thrombolytic therapy, and who presented to hospitals without on site PTCA. Patients were randomized to emergent transfer for primary PTCA or to on-site thrombolysis. The primary endpoint was a 30-days composite of major adverse cardiac events (MACE) including death, recurrent MI, and disabling stroke.
Due to poor recruitment, the study was terminated after enrollment of 138 patients (32% of the projected sample size). Of these, 67 patients were randomized to thrombolytic therapy, and 71 patients were randomized to emergency transfer and primary PTCA. The median door to therapy time were 51 minutes in the thrombolytic therapy group and 155 minutes in the transfer group. Most of the delay in treatment in the transfer group was due to initiation of transfer (43 minutes) and transport time (26 minutes), while time from arrival to hospital to catheterization laboratory (11 minutes) and time from catheterization laboratory arrival to treatment (14 minutes) were short. No deaths occurred during transfer. In the transfer group, 100% of patients underwent cardiac catheterization, 89% had primary PTCA, 2 patients were treated medically and 6 patients were referred for coronary artery bypass surgery. Coronary stents were used in 34% of patients. At 30-days follow-up, there was a non-significant trend toward a lower incidence of the combined endpoint in the transfer group when compared with the thrombolytic therapy group (8.4% versus 13.6% P = 0.331). Multivariate logistic regression analysis identified randomization to transfer as independent predictor of a reduction in the primary end-point (OR 0.159, 95% CI 0.031-0.820, p=0.028).
The results are interesting, but due to the small sample size, the incomplete recruitment, the short follow-up time, and lack of data on individual endpoints, it is not possible to draw definitive conclusions. Nonetheless, the study has important value in its attempt to further advance optimization of therapy for patients with acute myocardial infarction. It remains to be determined how this modality will position itself within the group of emerging strategies including primary PCI without surgical back up on site, facilitated PCI, and perhaps the development of “acute MI centers”.
Grines CL, Westerhausen DR, Grines LL et al. A Randomized Trial of Transfer for Primary Angioplasty vs. on-site Thrombolysis in Patients with High Risk Myocardial Infarction. The Air Primary Angioplasty in Myocardial Infarction Study. J Am Coll Cardiol 2002; 39:1713-9.
Keywords: Thrombolytic Therapy, Myocardial Infarction, Stroke, Cardiac Catheterization, Fibrinolytic Agents, Tissue Plasminogen Activator, Coronary Artery Bypass, Heart Rate, Logistic Models, Stents
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