Between 2005 and 2011, rates of cardiac catheterization laboratory false activation doubled while mean door-to-balloon times for primary PCI declined.
We sought to evaluate trends in door-to-balloon (D2B) times and false activation rates for the cardiac catheterization laboratory (CCL) in patients presenting to the emergency department (ED) with acute ST-elevation myocardial infarction (STEMI). In patients with STEMI, national efforts have focused on reducing D2B times for primary percutaneous coronary intervention (P-PCI). This emphasis on time-to-treatment may increase the rate of false CCL activations and unnecessary healthcare utilization.
Retrospective quality improvement chart review.
We examined all emergent CCL activations for P-PCI between 2007 and 2011 at the University of Michigan Hospital. False activation was defined as emergent CCL activation when the patient did not require CCL care or emergent cardiology evaluation in the ED. Pre-hospital or ED false activation rates and mean D2B time were retrospectively determined by chart review.
The CCL was activated 717 times for suspected STEMI. The number of CCL activations increased from 96 in 2007 to 190 in 2011. False CCL activations accounted for 28% of all prehospital and 29% of all ED activations. The false activation rate increased from 15% of all cases in 2007 to 40% of all cases in 2011. The median D2B time decreased from 67 minutes in 2007 to 55 minutes in 2011.
Over a 5-year period with a strong emphasis on reducing D2B times, there has been an increased CCL false activation rate for P-PCI.
Am J Manag Care. 2013;19(8):671-675This study examined the trend in false activation of the cardiac catheterization laboratory for patients with ST-elevation myocardial infarction (STEMI) since the introduction of national door-to-balloon initiatives.
The American College of Cardiology/American Heart Association (ACC/AHA) guidelines for management of ST-elevation myocardial infarction (STEMI) recommend that patients should be treated with primary percutaneous coronary intervention (P-PCI) within 90 minutes of first medical contact.1,2 A national effort was started by the ACC in 2006 to reduce door-to-balloon (D2B) times, defined as the time from patient arrival at the hospital emergency department (ED) to reperfusion in the cardiac catheterization laboratory (CCL).3 This process included encouraging emergency medical service (EMS) providers (primarily paramedics) and ED physicians to activate the CCL prior to consultation with a staff cardiologist.3-6 Hospital D2B times are publically reported, so clinicians may feel pressure to rush and activate the CCL before a review of the patient’s presenting condition can be completed, and occasionally CCL may be activated when the patient does not have STEMI. While there is increasing awareness of false CCL activation, the change in false CCL activation over time has not been assessed since the ACC initiated the D2B Alliance campaign.
Goals of This Investigation
Our objective was to describe the trends in the rate of false CCL activation and D2B time at our institution over the 5 years following the national D2B initiative. We hypothesized that as D2B times have fallen, the rate of false CCL activations has increased.
METHODSSelection of Patients and Setting
Between January 1, 2007, and December 31, 2011, all adult patients with suspected STEMI that presented to the University of Michigan Health System ED were reviewed. This study was approved by the institutional review board at the University of Michigan, a large academic suburban hospital. Data were initially collected retrospectively in a quality improvement database by 1 author (JB) and then verified through the group paging system by another author (GDB). Additional data were abstracted from the chart using a predefined set of data elements by 2 authors (GDB, AK). Selected cases werereviewed by both abstractors, with any discrepancy resolved by consensus.
Study Design and Outcome Measures
For the purpose of this study, a false activation is defined as one in which the CCL was activated by EMS or the ED for new STEMI or left bundle branch block (LBBB), but the patient was determined by the interventional cardiologist to not require emergent transfer from the ED to the CCL for P-PCI. To be as inclusive as possible for other reasons for emergent activation of the CCL, patients deemed too unstable to transfer to the CCL, who refused cardiac catheterization, who presented with cardiac arrest, who died prior to arrival in the CCL, or who were taken to the CCL emergently for any other indication, were defined as true CCL activations. Findings in the CCL did not influence the determination of a true or false CCL activation. The decision to not take a patient to the CCL was made initially by the on-call interventional cardiology fellow and verified in all cases by the interventional cardiology attending.
The primary outcome was the rate of false CCL activation, defined as the number of false CCL activations divided by the total number of CCL activations. Discharge diagnoses, peak serum troponin levels, and results of any cardiac catheterization during the index hospitalization were reviewed for all patients and compared with the initial decision to proceed or not proceed emergently to the CCL. Patients were classified by the year they presented to the ED and by CCL activation location (pre-hospital or ED). Other variables examined included age and gender. The D2B time was calculated in minutes as the time from ED arrival until initial device deployment for reperfusion, when appropriate.
Logistic regression analysis was conducted to demonstrate the relationship between year of presentation, location of CCL activation, and true/false CCL activation, as well as D2B time and year of presentation. Adjusted odds ratios were calculated by incorporating the patient’s age and gender into the logistic regression analysis, but these did not impact the final model and so are not presented. Model fit was assessed with the Hosmer-Lemeshow goodness of fit test.7 Logistic regression analysis was also conducted to demonstrate the relationship between year of presentation and location of CCL activation independent of true/false CCL activation status. Statistical analyses were conducted with the use of SPSS version 19 (Armonk, New York).
Between January 1, 2007, and December 31, 2011, the CCL was activated 717 times for possible STEMI. The average patient age was 61.4 (standard deviation [SD] 14.4) years and 72.4% were male. Pre-hospital CCL activations ranged from 33% in 2007 to 52% in 2011. For those patients who received P-PCI, the median D2B time decreased from 67 (SD 37.2) minutes in 2007 to 55 (SD 33.6) minutes in 2011 (3.74 min/year, 95% confidence interval [CI] 1.36-6.11 min/year, P = .002, ).
True and False CCL Activations
There were 513 (72%) true CCL activations and 204 (28%) false CCL activations. Of the true CCL activations, 73 (14%) patients were never taken to the CCL due to pulseless electrical activity, ventricular fibrillation, hemodynamic instability, refusal, or death. Yearly false CCL activation rates ranged from 15% in 2007 to 40% in 2011, a 37% per year increase in the odds of false CCL activation (95% CI 21-56%, P <.001, Figure). Of the 717 CCL activations, 315 (44%) were pre-hospital activations (33% in 2007 to 52% in 2011, ). False CCL activations were similar for ED versus pre-hospital location (odds ratio 1.12, 95% CI0.62-2.07, P = .71).
Reasons for False CCL Activation
A reason for not proceeding with emergent cardiac catheterization was documented in the medical chart for 181 of the 204 (89%) false activation cases. These included electrocardiogram (ECG) unchanged compared with prior ECG (27%), non-STEMI (13%), early repolarization (13%), atrial fibrillation or atrial flutter (11%), ECG reinterpretation as a prior MI (6%), pericarditis (4%), prolonged chest pain (4%), supraventricular tachycardia (1%), and other etiologies (10%). LBBB was present in 39 (5%) patients, 27 (11%) with false CCL activations and 12 (2.6%) with true CCL activations. Of the 717 CCL activations, 471 (66%) were transferred to the CCL, declining from 76% in 2007 to 53% in 2011 (Table). STEMI was confirmed based on coronary angiography in 385 (88%) of those transferred to the CCL.
Angiography was subsequently performed in 30/204 (15%) patients with false CCL activation during their hospitalization and 15 (7%) were treated with PCI. Of these 15 cases, 3 had evidence of subtotal or complete coronary occlusion consistent with STEMI; the remainder had nonocclusive disease that was amenable to PCI. No documented chest pain was found for 68 (33%) patients with false activation and 153 (75%) had negative cardiac biomarkers during hospitalization.
The major finding of our study is that there has been a striking increase in CCL activations between 2007 and 2011, an increase primarily driven by a marked rise in false CCL activations. There was a 300% increase in pre-hospital activation rates compared with a 50% increase in ED activation rates. While we cannot directly link the increase in false CCL activations with the initiation of national D2B efforts, their concurrence is notable.
Some centers have reported false CCL activation rates notably lower than ours. A recent report of CCL activations from a STEMI network of 14 PCI-capable hospitals and 85 referral hospitals demonstrated a 15% false CCL activation rate in 2009.8 Another report from Minneapolis described a 9.2% false activation rate between 2003 and 2006, before the ACC introduced the D2B Alliance campaign.9 A group from South Korea reported a 10% false CCL activation rate after initiating a single page system for STEMI patients between 2009 and 2011.10
Other groups, however, have reported experiences similar to ours. McCabe and colleagues describe a 36% false CCL activation rate at 2 urban hospitals in California between 2008 and 2011.11 Kontos and colleagues also report a 24% false CCL activation rate at their center between 2006 and 2008.12 Mixon and colleagues report a 28% false activation rate in their 6-county Texas cohort between 2009 and 2010.13 Although these studies did not report on changes over time, they do describe that the reported finding of frequent false CCL activation is not unique to 1 individual center. This is likely occurring at many centers across the United States.
Risk of False CCL Activation
While some might argue that an increase in false CCL activations is the expected cost of efforts to decrease D2B times, it is not clear whether this assumption is valid. Despite a 37-minute decline in the median D2B time between 2003 and 2008, there has been no decline in mortality for STEMI patients in Michigan.14 While reperfusion therapy delays are associated with worse outcomes,15-17 inaccurate diagnosis also has potential clinical repercussions. When the CCL is activated emergently, resources must be collected and CCL prepared for a potential patient. During off hours, this often requires bringing in a full CCL team to begin preparing the CCL. During regular business hours, other patients’ cases are often delayed in order to create availability in the CCL for the emergent case.
High rates of false CCL activation can have negative effects on providers. There is reasonable concern for the “boy who cried wolf” phenomenon, sleep deprivation affecting clinical activities on the subsequent day, and potential lost productivity when CCL space is being prepared for a false CCL activation.13,18-20
Quality Improvement Process
When the national effort to reduce D2B times was started in 2006, our institution made significant changes to expedite care of patients with chest pain. In 2007, there was a large process shift from having cardiology consulted in the ED to having EMS or an ED physician activate the CCL independently. To ensure lower D2B times, the CCL staff and ED leadership encouraged ED physicians to activate the CCL “liberally,” including any patient with a reasonable cardiac presentation who presented with a positive troponin and/or concerning ECG changes. Since that time, a team of ED and CCL providers have met regularly to review cases and develop protocols.
Noting the increase in false activations, a multi-disciplinary group of ED and cardiology physicians, nurses, quality improvement staff, and EMS representatives have met to develop proposed changes to maintain low D2B times while decreasing false activation rates. Changes include making urgent cardiology consultation available in the ED for cases without a clear-cut STEMI presentation. We are also considering many of the suggestions put forth by Mixon and colleagues, which include EMS and ED education around ECG interpretation, investigating opportunities for ECG transmission for review, minimizing pre-hospital activation in the setting of LBBB, using a more formalized review process, and emphasizing the importance of chest pain in the clinical presentation.13 The importance of a multi-disciplinary team with strong partnership between cardiology, ED, and EMS providers must be emphasized.
Our study has a few limitations. First, this is a single-center report and may or may not be generalizable to other hospitals or systems. However, a few recent reports have described similarly high rates of false CCL activation.11,12 Second, retrospective data collection might induce a certain degree of bias.Third, D2B times are the results of a number of system effects, including access to rapid ECG on ED arrival, expedited ECG review by ED staff, rapid notification of the CCL team by the EMS or ED staff, and expedited movement of a patient from the ED to the CCL. While all of these were focused on during the 5-year study period and likely influenced the changing mean D2B time, we were not able to quantify them for this analysis. Care must be taken to not confuse the presented odds ratios with relative risk in this study, as the rate of false activation was not a rare event. Last, the reason for CCL cancellation was inferred from the ED admission and discharge documentation. While there often was not direct documentation from the cardiology consultant as to their reasoning for not pursuing P-PCI, we explored the ED documentation, subsequent inpatient documentation, any subsequent CCL documentation, and hospital discharge documentation to explore the reasons for emergent CCL cancellation.
In summary, although D2B times have decreased since 2007, the rate of false activations has risen. Quality improvement initiatives aimed at decreasing the false activation rate of the CCL for STEMI patients are needed. Studies demonstrating effective tools and healthcare system interventions to decrease false CCL activation rates while maintaining low D2B times would be beneficial. Author Affiliations: From Division of Cardiovascular Medicine, Department of Internal Medicine (GDB, SJC, ERB, HSG), Department of Internal Medicine (AK), Department of Emergency Medicine (JSD, SLK), and Quality Improvement Office (JB), University of Michigan Health System, Ann Arbor, MI.
Funding Source: None.
Author Disclosures: Dr Bates reports board membership of the AHA Mission Lifeline Science Task Force. The other authors (GDB, AK, JSD, SLK, JB, SJC, HSG) report no relationship or financial interest with any entity that would pose a conflict of interest with the subject matter of this article.
Authorship Information: Concept and design (GDB, JSD, SJC, HSG); acquisition of data (GDB, AK, SLK, JB); analysis and interpretation of data (GDB, AK, JSD, SLK, ERB, HSG); drafting of the manuscript (GDB); critical revision of the manuscript for important intellectual content (GDB, AK, JSD, JB, SJC, ERB, HSG); statistical analysis (GDB, SLK); administrative, technical, or logistic support (JB); and supervision (SLK, SJC, ERB).
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