Improving Door-to-Balloon Times in STEMI
Abstract & Commentary
By Jonathan Abrams, MD, Professor of Medicine, Division of Cardiology, University of New Mexico, Albuquerque. Dr. Abrams serves on the speaker's bureau for Merck, Pfizer, and Parke-Davis.
Synopsis: Significant reductions in door-to-balloon time for acute STEMI are accomplished by reducing the time required to activate the cardiac catherization lab.
Source: Bradley EH, et al. Strategies for Reducing the Door-to-Balloon Time in Acute Myocardial Infarction. N Engl J Med. 2006;355:2308-20.
Mortality rates for patients with acute st-segment elevation myocardial infarction (STEMI) have been stable for a number of years, and it has been difficult to lower death rates with current conventional therapies. A major advance was the recognition that immediate or early percutaneous intervention (PCI) or angioplasty is the preferred treatment for acute STEMI. This approach is more effective than the use of fibrinolytic therapy, particularly in patients presenting early. Nevertheless, improvements in PCI results in STEMI are desirable, particularly by improving the pathway from onset of chest pain to inflation of the balloon in the cardiac catheterization laboratory. This report is a cross-sectional analysis with respect to a number of hospital practices for the treatment of STEMI in 365 hospitals in the United States. The research was carried out via a survey document including 28 key hospital strategies utilized in the pathway of door-to-balloon time (DTBT). A detailed survey questionnaire was developed for hospital reporting "to determine the internal processes for identifying and treating patients with STEMI who undergo PCI." Eligible hospitals all utilized DTBT as a performance measure, and had a volume of at least 25 cases in 2004. The actual study period was April-September 2005. Medicare databases were used, as was web-based interactive communications with the hospitals. A total of 28 hospital strategies were defined as being potentially important in assessing DTBT in these hospitals; DTBT was reported as the median for each institution. Less than 25% of the hospitals were teaching or academic hospitals; 90% were located in urban areas. Rural and for-profit hospitals were significantly less likely to participate. Results: The annual number of PCIs performed was between 25 and > 60; 90% of hospitals had CABG capability. Thirty-five percent of institutions reported a median DTBT of < 90 minutes; half of the hospital cohort had a documented DTBT of between 90 and 120 minutes; 17% were > 120 minutes. A multi-variant model was developed utilizing a number of independent variables.
The data demonstrated a highly variable median DTBT, with most hospitals not meeting a DTBT < 90 minute interval, as recommended by AHA/ACC guidelines. Six of the 28 strategies identified to be associated with DTBT were related to a significantly lower DTBT, with several of the associations resulting in an estimated reduction of DTBT of 10-15 minutes. Hospitals that utilized a greater number of effective strategies "tended to have a shorter DTBT;" but these were generally in the minority.
Activation of the catheterization laboratory appeared to drive the DTBT, in general. Hospital practices related to this process are outlined in the text. By and large, they related to an emergency room physician activating the cath lab without prior consultation with the cardiologist, ideally utilizing a single call from the emergency department to a central page operator, who would then contact the cath lab staff as well as the interventional cardiologist. In addition, a priori expectations of prompt personnel arrival factored into shorter DTBT time; when staff was expected to arrive within 20 to 30 minutes after being paged, DTBT was shorter. Transmission of the electrocardiogram (ECG) before a patient arrived at the hospital was also an important factor in earlier activation of the cath lab and shorter DTBT. Hospitals that did not activate the system until a patient arrived had longer DTBT. Feedback of data to the emergency department and catheterization laboratory staff also resulted in faster DTBT. The more the key strategies employed by an institution, the shorter the median DTBT, with only a small minority of institutions achieving an average median time of < 90 minutes. The authors state that "many of the strategies are not commonly used in hospitals in the United States, which may account in part for the relatively poor performance of such hospitals in meeting guidelines…" Emergency room physician leadership as well as activation of the cath lab without involvement of a cardiologist were associated with reduced DTBT, but only utilized in 25% of hospitals. Similarly, a single call to a central page operator was a favorable process, but was used in only 15% of hospitals. Hospital coordination with emergency medical services was "strongly associated" with DTBT. The authors conclude that the survey information identified important specific policies and practices for facilitating rapid PCI in STEMI, and as such, correlated with median DTBT.
Commentary
The issue of rapid treatment of acute STEMI received considerable attention at the recent American Heart Association meeting in Chicago. This interesting report clearly documents that several core issues must be addressed by institutions that are willing and able to tackle the problem of delays in DTBT in STEMI. Specifically, increased reliance on emergency room personnel to start the chain of events resulting in activation of the cath lab and arrival of an interventional cardiologist and appropriate utilization of ECG information transmitted prior to hospital arrival are critical processes in the chain of events. Having cath lab staff and the interventional cardiologist arrive as quickly as possible makes obvious sense, and survey results confirm that this interval has a significant impact on reducing the DTBT. Nevertheless, it is unlikely that many hospitals will have an attending cardiologist in-house 24/7; cath lab personnel activation between 20-30 minutes would appear to be a reachable goal in most institutions.
Aside from raising the level of attention to this subject, there are some significant gaps in information arising from the survey approach. There is no discussion as to whether shorter DTBT resulted in better outcomes than those that are longer. No mortality and morbidity data are provided, thus making it difficult to assess whether the goal of a shorter DTBT does, in fact, make a difference in clinical outcomes. Furthermore, there is no information regarding the time from onset of chest pain to arrival to the hospital, a very substantial component of the chain of events leading from the onset of STEMI to the interventional procedure that is hoped to decrease the degree of myocardial damage. No cardiac function data are available that could be correlated with the median DTBT. As the authors note, this study does not include transfer patients from institutions without cath lab capability to the full-service institution. Information regarding need for repeat PCI and CABG is not available. It would be of considerable interest to see if there is a real connection between the reductions in the time from arriving at the hospital to opening the occluded vessel. Finally, it is clear that the proven strategies for reducing DTBT involve a commitment at all levels of the institution, including the emergency services, the emergency room, the cardiac cath lab, and the commitment of all individuals involved in this chain of events to improve our current practice. It is a sobering thought that the ideal < 90 minute time interval is reached so infrequently. Hospitals that were willing to participate in this survey had to utilize Medicare performance measures, and it is clear that, even in our best institutions with a major interest in this area, there is considerable room for improvement.
Interested readers should refer to a recently published review that deals with all aspects of STEMI interventions, including the use of 2B 3A agents, thrombotic therapies, and PCI. Ling HH, et al. Narrative Review: Reperfusion Strategies for ST-Segment Elevation Myocardial Infarction. Annals of Internal Medicine. 2006;145:610-7.
Significant reductions in door-to-balloon time for acute STEMI are accomplished by reducing the time required to activate the cardiac catherization lab.You have reached your article limit for the month. Subscribe now to access this article plus other member-only content.
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