Source: Thrombolytic therapy vs primary percutaneous coronary intervention for myocardial infarction in patients presenting to hospitals without on-site cardiac surgery. JAMA 2002;287:1943-1951.
The availability of primary percutaneous coronary intervention (PCI) for acute myocardial infarction (MI) largely has been limited to hospitals with immediate surgical backup available in the event of complications. In this study, the authors report the findings of the Atlantic C-PORT (Cardiovascular Patient Outcomes Research Team) trial, which compared PCI vs. thrombolytic therapy for acute MI patients at hospitals that did not have backup cardiac surgery or bypass capability.
During the study period, from 1996 through 1999, 11 hospitals in Maryland and Massachusetts without cardiac surgery backup underwent a three-month training period to develop a primary PCI program for acute MI patients. This program included teaching and training of staff, initiation of practice standards, and the development of a quality management program (details are available at www.cport.org). Hospitals were required to have a coronary care unit, existing cardiac catheterization laboratory, intra-aortic balloon pump capability, ability to measure activated clotting times, and interventional operators with a minimum of 50 interventions per year.
At these sites, acute MI patients requiring reperfusion (ST elevation in contiguous leads or new left bundle-branch block [LBBB] in patients presenting with chest pain of 30 minutes to 12 hours in duration) were randomized to receive either accelerated-dose tissue plasminogen activator (tPA) (226 patients) or primary PCI (225 patients). Median time for tPA patients (door-to-drug) was 46 minutes, and for PCI patients (door-to-lab/balloon inflation) was 55/101.5 minutes. The investigators report that patients who underwent PCI had significantly lower rates of the combined endpoint of death, recurrent MI, or stroke at hospital discharge (9.8% vs 16.8%), 6 weeks (10.7% vs 17.7%), and 6 months (12.4% vs 19.9%).
This difference was most striking in the rates of recurrent MI. Accordingly, primary PCI patients had lower rates of subsequent cardiac catheterization and PCI (outside the study protocol) after their MI. There was a trend toward a lower rate of subsequent coronary artery bypass graft (CABG) in the primary PCI group as well. Interestingly, nearly twice as many PCI patients required blood transfusion compared with thrombolytic patients.
Based on their findings, the C-PORT investigators conclude that with an intensive development program, primary PCI can be performed safely and effectively in the community hospital setting without immediate cardiac surgery backup capability. Moreover, the authors conclude that such primary PCI is superior to accelerated thrombolytic therapy for the treatment of acute MI in this setting.
Commentary by Theodore C. Chan, MD, FACEP
This study represents the second largest randomized trial comparing primary PCI against thrombolytic therapy for acute MI reperfusion. Moreover, the C-PORT study is the only randomized trial in this country performed at hospitals without immediate cardiac surgery backup, once thought to be essential for the emergent mechanical reperfusion strategy.
This study adds to a growing body of literature suggesting that primary PCI results in improved clinical outcomes when compared to thrombolytic therapy.1 While not a requirement for this study, many of the patients in the PCI group were undoubtedly treated with stents and glycoprotein inhibitors, advances that likely played a role in the superior outcome in the PCI group. Further advances (such as coated stents) may continue to improve clinical outcomes associated with primary PCI.
The findings of this study, however, are limited, primarily by its small sample size. In fact, enrollment fell well below the investigators goal of 2550 subjects initially estimated to be needed by power analysis. As a result, this study sheds little light on the role of hospital volume and its impact on the PCI vs. thrombolytic debate.2
Moreover, no PCI patient actually required emergent CABG or cardiac surgery in this trial. With a larger population, some patients would have suffered these expected, though rare complications, such as perforation or dissection. How these hospitals would have cared for such a patient remains unclear (interestingly, two patients in the thrombolytic group did require CABG after PCI at another institution).
Finally, it remains to be determined whether large numbers of community hospitals are prepared to dedicate the resources needed to maintain primary PCI programs. The fact that the Atlantic C-PORT trial had to be suspended well short of its enrollment goals because funding could not be secured for its completion is a telling sign.
Dr. Chan, Associate Clinical Professor of Medicine, Emergency Medicine, University of California, San Diego, is on the Editorial Board of Emergency Medicine Alert.
References
1. Weaver WD, et al. Comparison of primary coronary angioplasty and intravenous thrombolytic therapy for AMI: A quantitative review. JAMA 1997;336:2093-2098.
2. Magid DJ, et al. Relation between hospital primary angioplasty volume and mortality for patients with acute MI treated with primary angioplasty vs thrombolytic therapy. JAMA 2000;284:3131-3138.
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