Regional Transfer Programs for Primary Percutaneous Coronary Intervention
David M. Larson
Timothy D. Henry
Primary percutaneous coronary intervention (PCI) is the preferred reperfusion strategy in patients with ST-elevation myocardial infarction (STEMI) who present to hospitals with cardiac catheterization labs (1,2). Availability is the major limitation to widespread adoption of this strategy because 25% of hospitals in the United States have the ability to perform primary PCI (3). Delays resulting from the transfer of STEMI patients may offset the expected benefits of primary PCI in mortality and morbidity (4). One approach to expand the availability of primary PCI is the use of prehospital electrocardiogram (EKG) for early diagnosis of STEMI and to then bypass non-PCI hospitals (2). However, 50% of STEMI patients in the United States do not present by ambulance and would require ad hoc interhospital transfer to benefit from primary PCI (5). In rural communities, this strategy would result in long transfer times prior to the initial medical assessment, definitive diagnosis, and use of adjunctive medications. Therefore, an alternative approach is to transfer STEMI patients who present at rural and community hospitals without PCI capability to PCI centers. Recent data suggest an organized, integrated regional transfer system can expand the potential benefits of primary PCI to a large segment of the population (6).
Transfer for Primary PCI Trials
Several European trials have demonstrated that transfer of STEMI patients from community hospitals for primary PCI is safe and effective. The first of these was the Primary Angioplasty After Transport of Patients from General Community Hospitals to Catheterization Units With/Without Thrombolysis Infusion (PRAGUE-1) study (7). In this trial, patients with STEMI from the Czech Republic were randomized to one of three groups. Patients in Group A received intravenous streptokinase (SK) and were admitted to the community hospital; Group B patients received SK and were transferred immediately for primary PCI; and Group C patients were transferred to the PCI center without fibrinolytics for primary PCI. The combined primary endpoint of death/reinfarction/stroke at 30 days was 23% in Group A, 15% in Group B, and 8% in Group C (P <0.02). There were no deaths during transfer, and the average door-to-balloon time from the community hospital in Group C was 95 minutes.
Subsequently a larger, multicenter, nationwide trial (PRAGUE-2) randomized 850 STEMI patients presenting to community hospitals without cardiac catheterization laboratory to SK versus immediate transfer for primary PCI (8). The primary endpoint was 30-day mortality, and the maximum transfer distance was 120 km. There was a trend toward reduction in mortality in the transfer group based on intent to treat (6.8% vs. 10.0%; P = 0.12). However, the mortality difference in the 360 patients who actually underwent primary PCI was 6.0% versus 10.4% in those who received fibrinolysis (P <0.05). Subgroup analysis demonstrated that those patients randomized <3 hours from symptom onset had no difference in mortality, and those patients randomized at >3 hours had a significant reduction in mortality favoring transfer for primary PCI (6.0% vs. 15.3%; P <0.02) (8).
A French multicenter study (CAPTIM) utilizing mobile emergency care units (SAMU) staffed by physicians randomized 840 STEMI patients to prehospital fibrinolysis with accelerated alteplase versus primary PCI (9). All patients were transferred immediately to PCI centers. The primary endpoint, the composite of death, nonfatal reinfarction, and nonfatal disabling stroke at 30 days was 6.2% in the primary PCI group versus 8.2% in the prehospital fibrinolysis group (P = 0.29). Mortality rates were not different in the two groups, but there was a trend toward increased stroke and nonfatal recurrent infarction in the fibrinolysis group. Rescue PCI was performed in 26% of the prehospital fibrinolysis patients. The median time from randomization to treatment was 27 minutes for fibrinolysis versus 82 minutes for primary PCI. At 1 year the composite endpoint was 16.4% for prehospital fibrinolysis versus 14% for primary PCI (P = NS); however, the overall costs were less for the primary PCI group both during the in-hospital period and at 1-year follow-up due to a high rate of subsequent revascularization in the fibrinolysis group (10).
The largest transfer for primary PCI trial, the Danish Multicenter Randomized Trial on Thrombolytic Therapy Versus Acute Coronary Angioplasty in Myocardial Infarction (DANAMI-2), randomized 1,572 STEMI patients presenting to both PCI centers and community hospitals to front-loaded alteplase versus primary PCI (11). The primary endpoint was the composite of death, reinfarction, or disabling stroke at 30 days. Of the 1,129 patients randomized at the non-PCI hospitals, the primary endpoint was 8.5% in the transfer for primary PCI group and 14.2% in the fibrinolysis group (P = 0.002). There was no significant difference in mortality (6.6% in the primary PCI group vs. 7.8% in the fibrinolysis group; P = 0.35) or stroke (1.1% vs. 2.0%; P = 0.15); however, there was a significant reduction in the rate of reinfarction (1.6% vs. 6.3%; P < 0.001). In the patients who were transferred for primary PCI (distance, 3–150 km), the median time from arrival at the community hospital to transfer was 50 minutes, transport time 32 minutes, and arrival at PCI center to balloon was 26 minutes. There were no deaths during transfer, but eight patients had ventricular fibrillation requiring cardioversion.
The Air Primary Angioplasty in Myocardial Infarction (Air-PAMI) Study was a predominantly U.S. trial that randomized high-risk STEMI patients to transfer for primary PCI versus on-site fibrinolysis (12). Difficulties in recruitment resulted in termination of the study after only 138 patients (32% of anticipated sample size) were randomized. The primary endpoint of major adverse cardiac events was 8.4% in the primary PCI group versus 13.6% in the fibrinolysis group. Because of the small sample size, this did not reach statistical significance (P = 0.331). Compared with the European trials, the Air-PAMI trials had greater delays in time to treatment (arrival at the community hospital to balloon inflation at PCI hospital was 155 min).
Each of the aforementioned trials was included in a recent meta-analysis of six trials (3,750 patients) comparing transfer for PCI versus fibrinolysis (13). The combined endpoint of death/reinfarction/stroke at 30 days was reduced by 42% (95% CI, 29% to 53%, P <0.001) favoring transfer for primary PCI. There was also a trend toward reduction of all cause mortality by 19% (95% CI, −3% to 36%; P = 0.08) (Fig. 3-1A,B). If the CAPTIM trial (actually prehospital fibrinolysis with a high rate of rescue PCI) is excluded from this meta-analysis, the mortality benefit for transfer for primary PCI is also significant.
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