Author + information
- Cindy L. Grines, MD⁎ ( and )
- Theodore Schreiber, MD
- ↵⁎Reprint requests and correspondence:
Dr. Cindy L. Grines, Academic and Clinical Affairs, Detroit Medical Center Cardiovascular Institute, 3990 John R Street, Detroit, Michigan 48201
Primary percutaneous coronary intervention (PCI) has become the predominant reperfusion strategy for ST-segment elevation myocardial infarction (STEMI) throughout western healthcare systems. Recent estimates in the United States suggest that primary PCI is used in 85% of all STEMI cases that undergo reperfusion, with thrombolytic agents used in only 9% and the combination of thrombolytic agents with PCI in 6% (1). This dramatic switch from thrombolytic therapy to primary PCI was the result of several studies conducted in the early 1990s that demonstrated the superiority of primary PCI at reducing stroke and reinfarction as well as an absolute reduction in mortality by 2% (2). These benefits were achieved despite a median door-to-balloon time (D2BT) of 120 min in many of the studies (3). The ability to achieve early and complete reperfusion is important, with additional prognostic factors including age, comorbidities, previous myocardial infarction or congestive heart failure, and infarct size. Early reports demonstrated that prolonged D2BTs were associated with worse survival (4–7); however, little attention was paid to the fact that sicker patients have more delay. Moreover, the marked differences in survival could not have been due simply to a delay in reperfusion (40% reduction in survival with a 30-min delay) (4) because these mortality differences were greater than what would be expected if the patient never had reperfusion (8,9).
Because D2BT is easily determined, it quickly became a measure of quality of care. Initiatives such as Mission Lifeline and the D2B initiative, as well as widespread education, publishing of individual hospital D2BTs, and its use as a core measure of institutional quality, have dramatically improved delays in reperfusion. Conversely, some have argued that this intense focus on time to treatment has led to less time spent in thoughtful diagnosis. Unfortunately, rapid triage to the cath lab has contributed to misdiagnosis and inappropriate treatment in a minority of suspected STEMI cases. Furthermore, despite impressive reductions in D2BTs, the mortality of patients undergoing primary PCI has not fallen as much as expected. In fact, data from the state of Michigan demonstrate that despite a 37-min reduction in median D2BT from 113 to 76 min, mortality remained unchanged at 4% (10). These observations highlight the need to pause, reflect, and reconsider what options may further benefit the STEMI patient.
One potential explanation for the less-than-expected benefit with shorter D2BTs is that many patients who undergo primary PCI are young, have small to moderate-sized infarctions, and are treated more than 3 h from symptom onset; these patients may not be expected to have a mortality advantage from small improvements in time to reperfusion (11). Conversely, many patients with delay in reperfusion have high-risk features, such as diabetes, advanced age, heart failure, and respiratory distress (12), and these factors cannot be altered by improvements in the system of care.
In a paper in this issue of the Journal, a total of 82,678 STEMI patients enrolled in the National Cardiovascular Data Registry were analyzed for nonsystem (e.g., patient) delays (13). The data collection listed 4 possible reasons for nonsystem delay. As expected, these delays were more frequent in sicker patients (older, female, African American, greater comorbidities) and were associated with a marked increase in mortality (15.1% compared with 2.5% in primary PCI patients without a nonsystem delay).
Clearly, one would not expect a 6-fold difference in mortality with only a 30-min difference in the median D2BTs (92 min vs. 63 min in patients without delay) (13). Moreover, patients with cardiac arrest or who required intubation had the highest mortality despite the shortest D2BT (median: 84 min). The importance of this study is that it demonstrates that delay, in and of itself, is probably not responsible for huge differences in mortality. It is likely a marker for higher risk patients, and the extent of risk is difficult to ascertain in retrospective studies. However, the frail nature of patients with nonsystem delay was further demonstrated by the marked increase in noncardiac events such as stroke, bleeding, vascular complications, and renal failure; events that are not related to delay in reperfusion. Unfortunately, this study is limited by its retrospective, observational nature and the fact that 31% of the reasons for nonsystem delay were unclassified (“other”). Key information that may be useful in understanding these patients, such as the time from chest pain onset to presentation, delay in obtaining the electrocardiogram, and association with other “system” delays, was not provided.
Continuing our intense focus on D2BT may encourage some physicians to “game the system” by withholding primary PCI in patients who are sick or who are anticipated to have long D2BTs. Although these physicians may still satisfy the core measure of reperfusion by giving thrombolytic agents in this situation, this strategy may not be in the patient's best interest. Although we have dramatically shortened D2BTs and increased the proportion of STEMI patients treated with primary PCI (instead of thrombolytic therapy), the proportion of reperfusion-eligible STEMI patients who are not treated has remained unchanged over the past several years (14). To further improve prognosis, physicians need to focus more on providing primary PCI to more patients, especially the STEMI cases at highest risk.
We have come a long way in the management of the STEMI patient, but we should not rest on our laurels. Clearly, the worst prognosis is in patients in whom reperfusion therapy is withheld. As clinicians, we need to make a concerted effort to provide early reperfusion to more patients. More widespread use of pre-hospital electrocardiograms, bypassing a non-PCI center in preference for a tertiary care center, better public education about recognizing symptoms, and calling 911 are essential for continued improvement in the management of all STEMI patients. We hope that with advances in hemodynamic support, methods to reduce reperfusion injury, systemic cooling of the cardiac arrest patient, and stem cell myogenesis in the setting of large infarction, the prognosis may be further improved for those myocardial infarction patients at highest risk.
Both authors have reported that they have no relationships relevant to the contents of this paper to disclose.
↵⁎ Editorials published in the Journal of the American College of Cardiology reflect the views of the authors and do not necessarily represent the views of JACC or the American College of Cardiology.
- American College of Cardiology Foundation
- ↵Action Registry Data July 1, 2009 to June 30, 2010. http://www.cardiosource.org. Accessed February 26, 2013.
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