Effect of Prehospital Cardiac Catheterization Lab Activation on Door-to-Balloon Time, Mortality, and False-Positive Activation

A mobile application for STEMI care optimization: Pilot implementation project report

BACKGROUND

Clinical outcomes of patients presenting with STEMI are significantly improved by reducing time from vessel occlusion to coronary blood flow restoration. In an effort to improve outcomes, we developed a secure mobile application, STEMIcathAID, and designed a pilot project implementing the app into the workflow for STEMI patients transfer. The aim of the study is to assess the impact of the app on key metrics for STEMI transfer before (historic) and after app launch.

METHODS

The pilot project included physicians, nurses and technicians from the Emergency Medicine and Nursing Departments at the referring center, the catheterization laboratory and transfer center. From July 2021 to February 2023, the referring center activated STEMIcathAID alarms in parallel with the previously established STEMI activation with traditional phone call to transfer center.

RESULTS

One hundred eleven suspected STEMI calls were activated through the app with 66 accepted and 45 rejected cases; thirty-one STEMI cases with available device time were compared with 42 STEMIs activated through the traditional pathway before the app implementation. Median door-to-device time for STEMIcathAID-assisted transfer decreased from 106 to 86 min (p < 0.001). The significant improvement, 20 min (19%), of the key metric for interhospital transfer resulted in all STEMI cases meeting the AHA goal of door-to-device time ≤ 120 min. In addition, median door-in-door-out time at the referral hospital decreased from 56 to 50 min (p = 0.01).

CONCLUSIONS

Implementation of a mobile app into STEMI workflow of a large urban healthcare system significantly improved the quality of care for transfer of STEMI patients.

TRIAL REGISTRATION

AHA Get With The Guidelines-Coronary Artery Disease® (GWTG-CAD) registry is a national quality improvement program and is not subject to the institutional review board approval.

Ethnic Disparities of Arrival Following ST Elevation Myocardial Infarction in South Israel

Background: Early activation of the emergency medical service (EMS) is crucial for the care of patients with STEMI. Methods: A retrospective cohort study of patients hospitalized with STEMI was conducted. Two groups of patients were compared: Bedouins and Jews. The primary outcome was one-year mortality. The secondary endpoints were 30-day mortality, mode of transportation and door-to-balloon time. Results: There were 445 Bedouin patients (BPs) and 1103 Jewish patients (JPs). BPs with STEMI were significantly younger than JPs, had more diabetes and higher rates of smoking. More JPs arrived at the hospital by ambulance compared to BPs (56.9% vs. 31.9%, p < 0.001). Direct transportation to the catheterization laboratory was observed in 51.9% of JPs and in 43.6% of BsP, p = 0.003. Door-to-balloon time was longer in BPs compared to JPs (median 65 min vs. 62 min, p = 0.044). There were no differences in one-year, 30-day and in-hospital mortality between the two groups. After adjustment by propensity score analysis for JPs vs. BPs, there was a protective factor for one-year mortality (hazard ratio (HR), 0.68; 95% CI 0.48-0.97), p = 0.034. Thirty-day and one-year mortality in the subgroup of BPs that arrived at the hospital from the outpatient clinic was higher compared to JPs (7.1% vs. 4.4%, p = 0.004 and 10.4% vs. 5.6%, p < 0.001, relatively) Conclusions: Underuse of EMS by BPs with STEMI compared to JPs resulted in a delay in direct transportation to the catheterization laboratory, longer door-to-balloon time and a higher 30-day and one-year mortality in the subgroup of BPs who arrived at the hospital after visiting an outpatient clinic.

Artificial Intelligence Driven Prehospital ECG Interpretation for the Reduction of False Positive Emergent Cardiac Catheterization Lab Activations: A Retrospective Cohort Study

OBJECTIVES

Data suggest patients suffering acute coronary occlusion myocardial infarction (OMI) benefit from prompt primary percutaneous intervention (PPCI). Many emergency medical services (EMS) activate catheterization labs to reduce time to PPCI, but suffer a high burden of inappropriate activations. Artificial intelligence (AI) algorithms show promise to improve electrocardiogram (ECG) interpretation. The primary objective was to evaluate the potential of AI to reduce false positive activations without missing OMI.

METHODS

Electrocardiograms were categorized by (1) STEMI criteria, (2) ECG integrated device software and (3) a proprietary AI algorithm (Queen of Hearts (QOH), Powerful Medical). If multiple ECGs were obtained and any one tracing was positive for a given method, that diagnostic method was considered positive. The primary outcome was OMI defined as an angiographic culprit lesion with either TIMI 0-2 flow; or TIMI 3 flow with either peak high sensitivity troponin-I > 5000 ng/L or new wall motion abnormality. The primary analysis was per-patient proportion of false positives.

RESULTS

A total of 140 patients were screened and 117 met criteria. Of these, 48 met the primary outcome criteria of OMI. There were 80 positives by STEMI criteria, 88 by device algorithm, and 77 by AI software. All approaches reduced false positives, 27% for STEMI, 22% for device software, and 34% for AI (p < 0.01 for all). The reduction in false positives did not significantly differ between STEMI criteria and AI software (p = 0.19) but STEMI criteria missed 6 (5%) OMIs, while AI missed none (p = 0.01).

CONCLUSIONS

In this single-center retrospective study, an AI-driven algorithm reduced false positive diagnoses of OMI compared to EMS clinician gestalt. Compared to AI (which missed no OMI), STEMI criteria also reduced false positives but missed 6 true OMI. External validation of these findings in prospective cohorts is indicated.

A Novel Algorithm for Improving the Prehospital Diagnostic Accuracy of ST-Segment Elevation Myocardial Infarction

INTRODUCTION

Early detection of ST-segment elevation myocardial infarction (STEMI) on the prehospital electrocardiogram (ECG) improves patient outcomes. Current software algorithms optimize sensitivity but have a high false-positive rate. The authors propose an algorithm to improve the specificity of STEMI diagnosis in the prehospital setting.

METHODS

A dataset of prehospital ECGs with verified outcomes was used to validate an algorithm to identify true and false-positive software interpretations of STEMI. Four criteria implicated in prior research to differentiate STEMI true positives were applied: heart rate <130, QRS <100, verification of ST-segment elevation, and absence of artifact. The test characteristics were calculated and regression analysis was used to examine the association between the number of criteria included and test characteristics.

RESULTS

There were 44,611 cases available. Of these, 1,193 were identified as STEMI by the software interpretation. Applying all four criteria had the highest positive likelihood ratio of 353 (95% CI, 201-595) and specificity of 99.96% (95% CI, 99.93-99.98), but the lowest sensitivity (14%; 95% CI, 11-17) and worst negative likelihood ratio (0.86; 95% CI, 0.84-0.89). There was a strong correlation between increased positive likelihood ratio (r2 = 0.90) and specificity (r2 = 0.85) with increasing number of criteria.

CONCLUSIONS

Prehospital ECGs with a high probability of true STEMI can be accurately identified using these four criteria: heart rate <130, QRS <100, verification of ST-segment elevation, and absence of artifact. Applying these criteria to prehospital ECGs with software interpretations of STEMI could decrease false-positive field activations, while also reducing the need to rely on transmission for physician over-read. This can have significant clinical and quality implications for Emergency Medical Services (EMS) systems.

Performance analysis of a STEMI network: prognostic impact of the type of first medical contact facility

INTRODUCTION AND OBJECTIVES

Prognosis in ST-elevation myocardial infarction (STEMI) is determined by delay in primary percutaneous coronary intervention (PPCI). The impact of first medical contact (FMC) facility type on reperfusion delays and mortality remains controversial.

METHODS

We performed a prospective registry of primary coronary intervention (PCI)-treated STEMI patients (2010-2020) in the Codi Infart STEMI network. We analyzed 1-year all-cause mortality depending on the FMC facility type: emergency medical service (EMS), community hospital (CH), PCI hospital (PCI-H), or primary care center (PCC).

RESULTS

We included 18 332 patients (EMS 34.3%; CH 33.5%; PCI-H 12.3%; PCC 20.0%). Patients with Killip-Kimball classes III-IV were: EMS 8.43%, CH 5.54%, PCI-H 7.51%, PCC 3.76% (P <.001). All comorbidities and first medical assistance complications were more frequent in the EMS and PCI-H groups (P <.05) and were less frequent in the PCC group (P <.05 for most variables). The PCI-H group had the shortest FMC-to-PCI delay (median 82 minutes); the EMS group achieved the shortest total ischemic time (median 151 minutes); CH had the longest reperfusion delays (P <.001). In an adjusted logistic regression model, the PCI-H and CH groups were associated with higher 1-year mortality, OR, 1.22 (95%CI, 1.00-1.48; P=.048), and OR, 1.17 (95%CI 1.02-1.36; P=.030), respectively, while the PCC group was associated with lower 1-year mortality than the EMS group, OR, 0.71 (95%CI 0.58-0.86; P <.001).

CONCLUSIONS

FMC with PCI-H and CH was associated with higher adjusted 1-year mortality than FMC with EMS. The PCC group had a much lower intrinsic risk and was associated with better outcomes despite longer revascularization delays.

Detection of Ischemic ST-Segment Changes Using a Novel Handheld ECG Device in a Porcine Model

Background

Portable, smartphone-sized electrocardiography (ECG) has the potential to reduce time to treatment for patients suffering acute cardiac ischemia, thereby lowering the morbidity and mortality. In the UMC Utrecht, a portable, smartphone-sized, multi-lead precordial ECG recording device (miniECG 1.0, UMC Utrecht) was developed.

Objectives

The purpose of this study was to investigate the ability of the miniECG to capture ischemic ECG changes in a porcine coronary occlusion model.

Methods

In 8 animals, antero-septal myocardial infarction was induced by 75-minute occlusion of the left anterior descending artery, after the first or second diagonal. MiniECG and 12-lead ECG recordings were acquired simultaneously before, during and after coronary artery occlusion and ST-segment deviation was evaluated.

Results

During the complete occlusion and reperfusion period, miniECG showed large ST-segment deviation in comparison to 12-lead ECG. MiniECG ST-segment deviation was observed within 1 minute for most animals. The miniECG was positive for ischemia (ie, ST-segment deviation ≥1 mm) for 99.7% (Q1-Q3: 99.6%-99.9%) of the occlusion time, while the 12-lead was only positive for 79.8% (Q1-Q3: 81.1%-98.7%) of the time (P = 0.018). ST-segment deviation reached maxima of 10.5 mm [95% CI: 6.5-14.5 mm] vs 5.0 mm [95% CI: 2.0-8.0 mm] for the miniECG vs 12-lead ECG, respectively.

Conclusions

MiniECG ST-segment deviation was observed early and was of large magnitude during 75 minutes of porcine transmural antero-septal infarction. The miniECG was positive for ischemia for the complete occlusion period. These findings demonstrate the potential of the miniECG in the detection of cardiac ischemia. Although clinical research is required, data suggests that the miniECG is a promising tool for the detection of cardiac ischemia.

Real-world, feasibility study to investigate the use of a multidisciplinary app (Pulsara) to improve prehospital communication and timelines for acute stroke/STEMI care

OBJECTIVES

To determine if a digital communication app improves care timelines for patients with suspected acute stroke/ST-elevation myocardial infarction (STEMI).

DESIGN

Real-world feasibility study, quasi-experimental design.

SETTING

Prehospital (25 Ambulance Victoria branches) and within-hospital (2 hospitals) in regional Victoria, Australia.

PARTICIPANTS

Paramedics or emergency department (ED) clinicians identified patients with suspected acute stroke (onset <4.5 hours; n=604) or STEMI (n=247).

INTERVENTION

The Pulsara communication app provides secure, two-way, real-time communication. Assessment and treatment times were recorded for 12 months (May 2017-April 2018), with timelines compared between 'Pulsara initiated' (Pulsara) and 'not initiated' (no Pulsara).

PRIMARY OUTCOME MEASURE

Door-to-treatment (needle for stroke, balloon for STEMI) Secondary outcome measures: ambulance and hospital processes.

RESULTS

Stroke (no Pulsara n=215, Pulsara n=389) and STEMI (no Pulsara n=76, Pulsara n=171) groups were of similar age and sex (stroke: 76 vs 75 years; both groups 50% male; STEMI: 66 vs 63 years; 68% and 72% male). When Pulsara was used, patients were off ambulance stretcher faster for stroke (11(7, 17) vs 19(11, 29); p=0.0001) and STEMI (14(7, 23) vs 19(10, 32); p=0.0014). ED door-to-first medical review was faster (6(2, 14) vs 23(8, 67); p=0.0001) for stroke but only by 1 min for STEMI (3 (0, 7) vs 4 (0, 14); p=0.25). Door-to-CT times were 44 min faster (27(18, 44) vs 71(43, 147); p=0.0001) for stroke, and percutaneous intervention door-to-balloon times improved by 17 min, but non-significant (56 (34, 88) vs 73 (49, 110); p=0.41) for STEMI. There were improvements in the proportions of patients treated within 60 min for stroke (12%-26%, p=0.15) and 90 min for STEMI (50%-78%, p=0.20).

CONCLUSIONS

In this Australian-first study, uptake of the digital communication app was strong, patient-centred care timelines improved, although door-to-treatment times remained similar.

Utility of prehospital electrocardiogram interpretation in ST-segment elevation myocardial infarction utilizing computer interpretation and transmission for interventional cardiologist consultation

Objectives

We examined the appropriateness of prehospital cardiac catheter laboratory activation (CCL‐A) in ST‐segment elevation myocardial infarction (STEMI) utilizing the University of Glasgow algorithm (UGA) and remote interventional cardiologist consultation.

Background

The incremental benefit of prehospital electrocardiogram (PH‐ECG) transmission on the diagnostic accuracy and appropriateness of CCL‐A has been examined in a small number of studies with conflicting results.

Methods

We identified consecutive PH‐ECG transmissions between June 2, 2010 and October 6, 2016. Blinded adjudication of ECGs, appropriateness of CCL‐A, and index diagnoses were performed using the fourth universal definition of MI. The primary outcome was the appropriate CCL‐A rate. Secondary outcomes included rates of false‐positive CCL‐A, inappropriate CCL‐A, and inappropriate CCL nonactivation.

Results

Among 1088 PH‐ECG transmissions, there were 565 (52%) CCL‐As and 523 (48%) CCL nonactivations. The appropriate CCL‐A rate was 97% (550 of 565 CCL‐As), of which 4.9% (n = 27) were false‐positive. The inappropriate CCL‐A rate was 2.7% (15 of 565 CCL‐As) and the inappropriate CCL nonactivation rate was 3.6% (19 of 523 CCL nonactivations). Reasons for appropriate CCL nonactivation (n = 504) included nondiagnostic ST‐segment elevation (n = 128, 25%), bundle branch block (n = 132, 26%), repolarization abnormality (n = 61, 12%), artefact (n = 72, 14%), no ischemic symptoms (n = 32, 6.3%), severe comorbidities (n = 26, 5.2%), transient ST‐segment elevation (n = 20, 4.0%), and others.

Conclusions

PH‐ECG interpretation utilizing UGA with interventional cardiologist consultation accurately identified STEMI with low rates of inappropriate and false‐positive CCL‐As, whereas using UGA alone would have almost doubled CCL‐As. The benefits of cardiologist consultation were identifying “masquerading” STEMI and avoiding unnecessary CCL‐As.

Systematic Review and Meta-Analysis of Diagnostic Accuracy to Identify ST-Segment Elevation Myocardial Infarction on Interpretations of Prehospital Electrocardiograms

Background: The aim of this study was to assess and discuss the diagnostic accuracy of prehospital ECG interpretation through systematic review and meta-analyses.

Methods and Results: Relevant literature published up to July 2020 was identified using PubMed. All human studies of prehospital adult patients suspected of ST-segment elevation myocardial infarction in which prehospital electrocardiogram (ECG) interpretation by paramedics or computers was evaluated and reporting all 4 (true-positive, false-positive, false-negative, and true-negative) values were included. Meta-analyses were conducted separately for the diagnostic accuracy of prehospital ECG interpretation by paramedics (Clinical Question [CQ] 1) and computers (CQ2). After screening, 4 studies for CQ1 and 6 studies for CQ2 were finally included in the meta-analysis. Regarding CQ1, the pooled sensitivity and specificity were 95.5% (95% confidence interval [CI] 82.5–99.0%) and 95.8% (95% CI 82.3–99.1%), respectively. Regarding CQ2, the pooled sensitivity and specificity were 85.4% (95% CI 74.1–92.3%) and 95.4% (95% CI 87.3–98.4%), respectively.

Conclusions: This meta-analysis suggests that the diagnostic accuracy of paramedic prehospital ECG interpretations is favorable, with high pooled sensitivity and specificity, with an acceptable estimated number of false positives and false negatives. Computer-assisted ECG interpretation showed high pooled specificity with an acceptable estimated number of false positives, whereas the pooled sensitivity was relatively low.

Evaluating the cost-utility of a direct transfer to angiosuite protocol within 6 h of symptom onset in suspected large vessel occlusion patients

INTRODUCTION

A direct transfer to angiosuite (DTAS) protocol has shown to be effective and safe by shortening in-hospital workflows and encouraging long-term outcome benefits. To implement DTAS at a new facility, a large organizational effort is necessary. We performed a cost-utility analysis and budget impact analysis (BIA) of the operation of a new angiosuite, primarily dedicated to stroke patients, that allows facilities to approximate the cost implications of utilizing a DTAS pathway.

METHODS

Sixty-one patients who underwent endovascular treatment (EVT) following DTAS were matched for baseline variables to 117 patients who underwent a conventional imaging protocol at a hospital in Catalonia, Spain. An economic model, based on actual data from these patients, was developed to assess the short- and long-term clinical and economic implications of DTAS. In the BIA, the DTAS scenario was gradually implemented for 20% of patients each year until reaching a plateau at 80% of patients in the DTAS pathway. Initial investment and additional organizational costs, €4 million, were taken into consideration to compare the budget impact of the DTAS scenario with no organizational changes over five years.

RESULTS

DTAS was associated with better patient functional independence rates (mRS 0-2: 50.9% vs. 41.0%) and a quality-adjusted life-years gain of 0.82 per patient. Despite the additional initial investment, DTAS development was associated with an estimated 10.2% reduction (€14.7 million) of the total costs (€144.5 million). Cost savings were mainly due to long-term associated costs related to patient disability (€13.2 million).

LIMITATIONS

The study relies on data obtained from a single-center, and therefore it may be difficult to generalize the findings.

CONCLUSIONS

Our economic model predicts that the implementation of a DTAS program is cost-effective compared with no organizational changes. Our model also predicts better clinical outcomes for patients in terms of functional independence and quality-adjusted life years.

Impact of Pre-Hospital Activation of STEMI on False Positive Activation Rate and Door to Balloon Time

BACKGROUND

Pre-hospital identification of ST-segment elevation myocardial infarction (STEMI) by paramedical staff reduces reperfusion time. However, the impact of this approach on the rate of unnecessary activation of coronary catheterisation lab (CCL) remains unclear.

METHODS

The study reviewed consecutive STEMI patients over 3 years (July 2015 to June 2018) from all primary percutaneous coronary intervention (PPCI) centres and inter-hospital transfers (IHT) from non-PPCI capable centres in Western Australia. Out-of-hospital cardiac arrests (OOHCA) and STEMI calls for in-patients receiving treatment for other medical reasons were excluded.

RESULTS

During the 3 years study period, 1,736 STEMI cases were recorded. Pre-hospital (PH) activation occurred in 799 (46%) cases. Median door to balloon time (D2BT) was 68 minutes (IQR 63 mins). D2BT for PH activation (40 min [IQR 25 min]) was significantly lower than both the PPCI centre emergency department (ED) activation (86 min [IQR 55 min]) and IHT activation groups (108 min [IQR 55 min]), p-value <0.00001. In PH activation group 98% patients received primary PCI in less than 90 minutes compared to 54% and 26% patients in the ED and the IHT activation groups, respectively. False positive STEMI activation rate was lower in the PH activation group (2.75%) compared to ED activation (5.4%) and IHT group (6%), p-value 0.0115. The false positive rate did not vary significantly between working hours and out-of-hour calls (5% vs 4%, p-value=0.304). Pericarditis, coronary artery disease other than STEMI, atypical chest pain, and stress induced cardiomyopathy were the common diagnoses in false positive activations.

CONCLUSION

Pre-hospital activation of STEMI leads to reduced door to balloon times without a significant increase in inappropriate procedures, though false positive activation rates are unclear. The majority of STEMI patients transferred from non-PPCI centres failed to receive reperfusion therapy within 90 minutes of initial hospital presentation. Further studies are required to assess the benefits of thrombolysis in selected patients in inter-hospital transfer group.

The Effect of Periprocedural Clinical Factors Related to the Course of STEMI in Men and Women Based on the National Registry of Invasive Cardiology Procedures (ORPKI) between 2014 and 2019

BACKGROUND

There are several sex-related differences in the course, management, and outcomes of ST-elevation myocardial infarction (STEMI). This study aimed to identify the risk factors that may affect the odds of procedure-related death in patients with STEMI.

METHODS

The observational cohort study group consisted of 118,601 participants recruited from the National Registry of Invasive Cardiology Procedures (ORPKI).

RESULTS

Procedure-related death occurred in 802 (1.0%) men and in 663 (1.7%) women. The odds of procedure-related death among women were significantly higher than among men (OR, 1.76; 95% CI, 1.59-1.95; p < 0.001). The probability of procedure-related mortality was highest in both men and women with cardiac arrest in the cath lab, critical stenosis of the left main coronary artery, and direct transfer to the cath lab. The factors that reduced the probability of procedure-related mortality in both men and women were thrombolysis in myocardial infarction (TIMI) flow grade and the use of P2Y12 inhibitors in the peri-infarct period. Psoriasis was associated with increased odds of procedure-related death among men, whereas cigarette smoking reduced the odds among women.

CONCLUSIONS

Procedure-related deaths occurred more frequently in women than men with STEMI. Additional scrutiny needs to be undertaken to identify factors influencing survival regarding gender differences.

Direct Transfer to Angiosuite in Acute Stroke: Why, When, and How?

Time to reperfusion is one of the strongest predictors of functional outcome in acute stroke due to a large vessel occlusion (LVO). Direct transfer to angiography suite (DTAS) protocols have shown encouraging results in reducing in-hospital delays. DTAS allows bypassing of conventional imaging in the emergency room by ruling out an intracranial hemorrhage or a large established infarct with imaging performed before transfer to the thrombectomy-capable center in the angiography suite using flat-panel CT (FP-CT). The rate of patients with stroke code primarily admitted to a comprehensive stroke center with a large ischemic established lesion is <10% within 6 hours from onset and remains <20% among patients with LVO or transferred from a primary stroke center. At the same time, stroke severity is an acceptable predictor of LVO. Therefore, ideal DTAS candidates are patients admitted in the early window with severe symptoms. The main difference between protocols adopted in different centers is the inclusion of FP-CT angiography to confirm an LVO before femoral puncture. While some centers advocate for FP-CT angiography, others favor additional time saving by directly assessing the presence of LVO with an angiogram. The latter, however, leads to unnecessary arterial punctures in patients with no LVO (3%-22% depending on selection criteria). Independently of these different imaging protocols, DTAS has been shown to be effective and safe in improving in-hospital workflow, achieving a reduction of door-to-puncture time as low as 16 minutes without safety concerns. The impact of DTAS on long-term functional outcomes varies between published studies, and randomized controlled trials are warranted to examine the benefit of DTAS.

Diagnostic performance of a new ECG algorithm for reducing false positive cases in patients suspected acute coronary syndrome

BACKGROUND

Early and correct diagnosis of ST-segment elevation myocardial infarction (STEMI) is crucial for providing timely reperfusion therapy. Patients with ischemic symptoms presenting with ST-segment elevation on the electrocardiogram (ECG) are preferably transported directly to a catheterization laboratory (Cath-lab) for primary percutaneous coronary intervention (PPCI). However, the ECG often contains confounding factors making the STEMI diagnosis challenging leading to false positive Cath-lab activation. The objective of this study was to test the performance of a standard automated algorithm against an additional high specificity setting developed for reducing the false positive STEMI calls.

METHODS

We included consecutive patients with an available digital prehospital ECG triaged directly to Cath-lab for acute coronary angiography between 2009 and 2012. An adjudicated discharge diagnosis of STEMI or no myocardial infarction (no-MI) was assigned for each patient. The new automatic algorithm contains a feature to reduce false positive STEMI interpretation. The STEMI performance with the standard setting (STD) and the high specificity setting (HiSpec) was tested against the adjudicated discharge diagnosis in a retrospective manner.

RESULTS

In total, 2256 patients with an available digital prehospital ECG (mean age 63 ± 13 years, male gender 71%) were included in the analysis. The discharge diagnosis of STEMI was assigned in 1885 (84%) patients. The STD identified 165 true negative and 1457 true positive (206 false positive and 428 false negative) cases (77.3%, 44.5%, 87.6% and 17.3% for sensitivity, specificity, PPV and NPV, respectively). The HiSpec identified 191 true negative and 1316 true positive (180 false positive and 569 false negative) cases (69.8%, 51.5%, 88.0% and 25.1% for sensitivity, specificity, PPV and NPV, respectively). From STD to HiSpec, false positive cases were reduced by 26 (12,6%), but false negative results were increased by 33%.

CONCLUSIONS

Implementing an automated ECG algorithm with a high specificity setting was able to reduce the number of false positive STEMI cases. However, the predictive values for both positive and negative STEMI identification were moderate in this highly selected STEMI population. Finally, due the reduced sensitivity/increased false negatives, a negative AMI statement should not be solely based on the automated ECG statement.

Temporal trends in the pre-procedural TIMI flow grade among patients with ST- segment elevation myocardial infarction - From the ACSIS registry

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Preprocedural TIMI flow grade remains of prognostic significance.

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Patients with TIMI 0 have a poorer prognosis than their counterparts with TIMI 1-3.

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In-hospital complications have decreased among patients with TIMI 0 over time.

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30-d MACE and 1-year mortality remained unchanged in those with TIMI 0 or 1-3.

Background

Pre-procedural TIMI coronary flow grade in patients with ST segment elevation myocardial infarction (STEMI) is associated with adverse clinical outcomes. There have been great advances in pharmacologic and invasive treatment of STEMI patients in the current era. We aimed to assess the temporal trends in clinical outcomes according to the TIMI flow grade amongst these patients.

Methods

Data of patients with STEMI from the acute coronary syndrome Israeli Survey (ACSIS) registry. A time-dependent analysis stratifying patient by TIMI flow grade 0 and TIMI flow grade 1–3 was performed. Survey years were divided to early (2008–2010) and late period (2013–2018). Clinical outcomes included in-hospital complications, 30d MACE (death, myocardial infarction, stroke, unstable angina, stent thrombosis, urgent revascularization) and 1-year mortality.

Results and Conclusions: Included were 2453 patients. The majority of patients had pre-procedural TIMI flow 0 (58.9% in the early period and 58.7% in the late period, P = 0.97). In-hospital complications of patients with TIMI flow 0 has significantly decreased over time (36.1% vs 26.8%, P < 0.001) but not amongst patients with TIMI flow 1–3. Compared with TIMI flow 1–3, patients with TIMI flow 0 had worse 30d MACE and 1-year mortality. There was no temporal change of these outcomes in either TIMI flow grade group. TIMI flow grade 0 is still more common among patients with STEMI and is associated with poorer prognosis. Nevertheless, over time, in-hospital complications have decreased among patients with TIMI 0, while 30d MACE and 1-year mortality has remained unchanged.

Mobile application to optimize care for ST-segment elevation myocardial infarction patients in a large healthcare system, STEMIcathAID: rationale and design

Aims

Technological advancements have transformed healthcare. System delays in transferring patients with ST-segment elevation myocardial infarction (STEMI) to a primary percutaneous coronary intervention (PCI) centre are associated with worse clinical outcomes. Our aim was to design and develop a secure mobile application, STEMIcathAID, streamlining communication, and coordination between the STEMI care teams to reduce ischaemia time and improve patient outcomes.

Methods and results

The app was designed for transfer of patients with STEMI to a cardiac catheterization laboratory (CCL) from an emergency department (ED) of either a PCI capable or a non-PCI capable hospital. When a suspected STEMI arrives to a non-PCI hospital ED, the ED physician uploads the electrocardiogram and relevant patient information. An instant notification is simultaneously sent to the on-call CCL attending and transfer centre. The attending reviews the information, makes a video call and decides to either accept or reject the transfer. If accepted, on-call CCL team members receive an immediate push notification and begin communicating with the ED team via a HIPAA compliant chat. The app provides live GPS tracking of the ambulance and frequent clinical status updates of the patient. In addition, it allows for screening of STEMI patients in cardiogenic shock. Prior to discharge, important data elements have to be entered to close the case.

Conclusion

We developed a novel mobile app to optimize care for STEMI patients and facilitate electronic extraction of relevant performance metrics to improve allocation of resources and reduction of costs.

The Effect of Implementation of the American Heart Association Mission Lifeline PreAct Algorithm for Prehospital Cardiac Catheterization Laboratory Activation on the Rate of "False Positive" Activations

HYPOTHESIS

Emergency Medical Services (EMS) systems have developed protocols for prehospital activation of the cardiac catheterization laboratory for patients with suspected ST-elevation myocardial infarction (STEMI) to decrease first-medical-contact-to-balloon time (FMC2B). The rate of "false positive" prehospital activations is high. In order to decrease this rate and expedite care for patients with true STEMI, the American Heart Association (AHA; Dallas, Texas USA) developed the Mission Lifeline PreAct STEMI algorithm, which was implemented in Los Angeles County (LAC; California USA) in 2015. The hypothesis of this study was that implementation of the PreAct algorithm would increase the positive predictive value (PPV) of prehospital activation.

METHODS

This is an observational pre-/post-study of the effect of the implementation of the PreAct algorithm for patients with suspected STEMI transported to one of five STEMI Receiving Centers (SRCs) within the LAC Regional System. The primary outcome was the PPV of cardiac catheterization laboratory activation for percutaneous coronary intervention (PCI) or coronary artery bypass graft (CABG). The secondary outcome was FMC2B.

RESULTS

A total of 1,877 patients were analyzed for the primary outcome in the pre-intervention period and 405 patients in the post-intervention period. There was an overall decrease in cardiac catheterization laboratory activations, from 67% in the pre-intervention period to 49% in the post-intervention period (95% CI for the difference, -14% to -22%). The overall rate of cardiac catheterization declined in post-intervention period as compared the pre-intervention period, from 34% to 30% (95% CI, for the difference -7.6% to 0.4%), but actually increased for subjects who had activation (48% versus 58%; 95% CI, 4.6%-15.0%). Implementation of the PreAct algorithm was associated with an increase in the PPV of activation for PCI or CABG from 37.9% to 48.6%. The overall odds ratio (OR) associated with the intervention was 1.4 (95% CI, 1.1-1.8). The effect of the intervention was to decrease variability between medical centers. There was no associated change in average FMC2B.

CONCLUSIONS

The implementation of the PreAct algorithm in the LAC EMS system was associated with an overall increase in the PPV of cardiac catheterization laboratory activation.

Catheterization Laboratory Activation Time in Patients Transferred With ST-Segment–Elevation Myocardial Infarction: Insights From the Mission: Lifeline STEMI Accelerator-2 Project

Background:

Catheterization laboratory (cath lab) activation time is a newly available process measure for patients with ST-segment–elevation myocardial infarction requiring inter-hospital transfers for primary percutaneous coronary intervention that reflects inter-facility communication and urgent mobilization of interventional laboratory resources. Our aim was to determine whether faster activation is associated with improved reperfusion time and outcomes in the American Heart Association Mission: Lifeline Accelerator-2 Project.

Methods and Results:

From April 2015 to March 2017, treatment times of 2063 patients with ST-segment–elevation myocardial infarction requiring inter-hospital transfer for primary percutaneous coronary intervention from 12 regions around the United States were stratified by cath lab activation time (first hospital arrival to cath lab activation within [timely] or beyond 20 minutes [delayed]). Median cath lab activation time was 26 minutes, with a delayed activation observed in 1241 (60.2%) patients. Prior cardiovascular or cerebrovascular disease, arterial hypotension at admission, and black or Latino ethnicity were independent factors of delayed cath lab activation. Timely cath lab activation patients had shorter door-in door-out times (40 versus 68 minutes) and reperfusion times (98 versus 135 minutes) with 80.1% treated within the national goal of ≤120 minutes versus 39.0% in the delayed group.

Conclusions:

Cath lab activation within 20 minutes across a geographically diverse group of hospitals was associated with performing primary percutaneous coronary intervention within the national goal of ≤120 minutes in >75% of patients. While several confounding factors were associated with delayed activation, this work suggests that this process measure has the potential to direct resources and practices to more timely treatment of patients requiring inter-hospital transfer for primary percutaneous coronary intervention.

Push Notifications Reduce Emergency Department Response Times to Prehospital ST-segment Elevation Myocardial Infarction

INTRODUCTION

Prehospital acquisition of electrocardiograms (ECG) has been consistently associated with reduced door-to-balloon times in the treatment of ST-segment myocardial infarction (STEMI). There is little evidence establishing best hospital practices once the ECG has been received by the emergency department (ED). This study evaluates the use of a push notification system to reduce delays in cardiac catheterization lab (CCL) activation for prehospital STEMI.

METHODS

In this prospective before-and-after study, we collected prehospital ECGs with computer interpretation of STEMI from May 2012 to October 2013. Push notifications were implemented June 1, 2013. During the study period, we collected timestamps of when the prehospital ECG was received (email timestamp of receiving account), CCL team activation (timestamp in paging system), and patient arrival (timestamp in ED tracking board). When prehospital ECGs were received in the ED, an audible alert was played via the Vocera WiFi communication system, notifying nursing staff that an ECG was available for physician interpretation. We compared the time from receiving the ECG to activation of the CCL before and after the audible notification was implemented.

RESULTS

Of the 56 cases received, we included 45 in our analysis (20 cases with pre-arrival CCL activation and 25 with post-arrival activation). For the pre-arrival group, the interval from ECG received to CCL activation prior to implementation was 9.1 minutes with a standard deviation (SD) of 5.7 minutes. After implementation, the interval was reduced to 3.33 minutes with a SD of 1.63 minutes. Delay was decreased by 5.8 minutes (p < 0.01). Post-implementation activation times were more consistent, demonstrated by a decrease in SD from 5.75 to 1.63 min (p < 0.01). For patients with CCL activation after arrival, there was no significant change in mean delay after implementation.

CONCLUSION

In this small, single-center observational study, we demonstrated that the use of push notifications to ED staff alerting that a prehospital STEMI ECG was received correlated with a small reduction in, and increased consistency of, ED CCL activation.

Sensitivity, specificity, and predictive value of cardiac symptoms assessed by emergency medical services providers in the diagnosis of acute myocardial infarction: a multi-center observational study

Objective

For patients with acute myocardial infarction (AMI), symptoms assessed by emergency medical services (EMS) providers have a critical role in prehospital treatment decisions. The purpose of this study was to evaluate the diagnostic accuracy of EMS provider-assessed cardiac symptoms of AMI.

Methods

Patients transported by EMS to 4 study hospitals from 2008 to 2012 were included. Using EMS and administrative emergency department databases, patients were stratified according to the presence of EMS-assessed cardiac symptoms and emergency department diagnosis of AMI. Cardiac symptoms were defined as chest pain, dyspnea, palpitations, and syncope. Disproportionate stratified sampling was used, and medical records of sampled patients were reviewed to identify an actual diagnosis of AMI. Using inverse probability weighting, verification bias-corrected diagnostic performance was estimated.

Results

Overall, 92,353 patients were enrolled in the study. Of these, 13,971 (15.1%) complained of cardiac symptoms to EMS providers. A total of 775 patients were sampled for hospital record review. The sensitivity, specificity, positive predictive value, and negative predictive value of EMS provider-assessed cardiac symptoms for the final diagnosis of AMI was 73.3% (95% confidence interval [CI], 70.8 to 75.7), 85.3% (95% CI, 85.3 to 85.4), 3.9% (95% CI, 3.6 to 4.2), and 99.7% (95% CI, 99.7 to 99.8), respectively.

Conclusion

We found that EMS provider-assessed cardiac symptoms had moderate sensitivity and high specificity for diagnosis of AMI. EMS policymakers can use these data to evaluate the pertinence of specific prehospital treatment of AMI.

Lack of Significant Coronary History and ECG Misinterpretation Are the Strongest Predictors of Undertriage in Prehospital Chest Pain

INTRODUCTION

Appropriate prehospital (PH) triage of patients with chest pain can significantly improve outcomes in acute myocardial infarction (MI). We sought to explore how PH providers triage chest pain as high versus low risk and to evaluate the accuracy and predictors of their triage decision.

METHODS

This was a prospective, observational cohort study that enrolled consecutive patients with chest pain transported by emergency medical services (EMS) to 3 tertiary care hospitals in the US. EMS triage decision (high risk versus low-risk) was defined based on the transmission of PH electrocardiogram (ECG) to a command center for medical consultation with or without catheter laboratory activation. Two independent reviewers examined in-hospital medical records to adjudicate the presence of acute MI and to audit the findings on the presenting ECG.

RESULTS

We enrolled 2,065 patients (aged 56 ± 17, 53% male) of whom 768 (37%) were triaged as high risk. Those triaged as high risk were older, were more likely to be men or have significant cardiac history, and had a higher rate of acute MI events (14.2% versus 3.5%). The sensitivity and specificity for triaging MI events as high risk were 70% and 97%, respectively. A total of 46/155 (30%) MI events were misclassified as low risk. No previous coronary revascularization and ECG misinterpretation were strong independent predictors of such undertriage.

CONCLUSIONS

PH providers have moderate sensitivity in triaging high-risk patients; 1 in 3 MI events are undertriaged. Emergency nurses need to pay special attention to patients with benign past histories during transition of care and should always reinterpret ECGs for subtle ischemic changes.

Diagnostic accuracy of prehospital electrocardiograms interpreted remotely by emergency physicians in myocardial infarction patients

BACKGROUND

Prehospital 12‑lead electrocardiogram (ECG) is the most widely used screening tool for recognition of ST-segment elevation myocardial infarction (STEMI). However, prehospital diagnosis of STEMI based solely on ECGs can be challenging.

OBJECTIVES

To evaluate the ability of emergency department (ED) physicians to accurately interpret prehospital 12‑lead ECGs from a remote location.

METHODS

All suspected prehospital STEMI patients who were transported by EMS and underwent angiography between 2006 and 2014 were included. We reviewed prehospital ECGs and grouped them based on: 1) presence or absence of a culprit artery lesion following angiography; and 2) whether they met the 3rd Universal Definition of Myocardial Infarction. We also described characteristics of ECGs that were misinterpreted by ED physicians.

RESULTS

A total of 625 suspected STEMI cases were reviewed. Following angiography, 94% (590/625) of patients were found having a culprit artery lesion, while 6% (35/625) did not. Among these 35 patients, 24 had ECGs that mimicked STEMI criteria and 9 had non-ischemic signs. Upon ECG reinterpretation, 92% (577/625) had standard STEMI criteria while 8% (48/625) did not. Among these 48 patients, 35 had ischemic signs ECGs and 13 did not. Characteristics of misinterpreted ECGs included pericarditis, early repolarization, STE > 1 mm (1‑lead only), and negative T-wave.

CONCLUSIONS

Remote interpretation of prehospital 12‑lead ECGs by ED physicians was a useful diagnostic tool in this EMS system. Even if the rate of ECG misinterpretation is low, there is still room for ED physicians operating from a remote location to improve their ability to accurately diagnose STEMI patients.

Keys to Achieving Target First Medical Contact to Balloon Times and Bypassing Emergency Department More Important Than Distance

Background

Australian guidelines advocate primary percutaneous coronary intervention (PPCI) as the reperfusion strategy of choice for ST elevation myocardial infarction (STEMI) in patients in whom it can be performed within 90 minutes of first medical contact; otherwise, fibrinolytic therapy is preferred. In a large health district, the reperfusion strategy is often chosen in the prehospital setting. We sought to identify a distance from a PCI centre, which made it unlikely first medical contact to balloon time (FMCTB) of less than 90 minutes could be achieved in the Hunter New England health district and to identify causes of delay in patients who were triaged to a PPCI strategy.

Methods and Results

We studied 116 patients presenting via the ambulance service with STEMI from January 2016 to December 2016. In patients who were taken directly to the cardiac catheterisation lab, a maximum distance of 50 km from hospital resulted in 75% of patients receiving PCI within 90 minutes and approximately 95% of patients receiving PCI within 120 minutes. Patients who bypassed the emergency department (ED) were significantly more likely to have FMCTB of less than 90 minutes (p < 0.001) despite having a longer travel distance (28.5 km versus 17.4 km, p < 0.001). Patients transiting via the ED were significantly more likely to present out of hours (60 versus 24.2% p < 0.001).

Conclusions

Patients who do not bypass the ED have a longer FMCTB across all spectrum of distances from the PCI centre; therefore, bypassing the ED is key to achieving target FMCTB times. Using a cutoff distance of 50 km may reduce human error in estimating travel time to our PCI centre and thereby identifying patients who should receive prehospital thrombolysis.

Weekly Checks Improve Real-Time Prehospital ECG Transmission in Suspected STEMI

IntroductionField identification of ST-elevation myocardial infarction (STEMI) and advanced hospital notification decreases first-medical-contact-to-balloon (FMC2B) time. A recent study in this system found that electrocardiogram (ECG) transmission following a STEMI alert was frequently unsuccessful.HypothesisInstituting weekly test ECG transmissions from paramedic units to the hospital would increase successful transmission of ECGs and decrease FMC2B and door-to-balloon (D2B) times.

METHODS

This was a natural experiment of consecutive patients with field-identified STEMI transported to a single percutaneous coronary intervention (PCI)-capable hospital in a regional STEMI system before and after implementation of scheduled test ECG transmissions. In November 2014, paramedic units began weekly test transmissions. The mobile intensive care nurse (MICN) confirmed the transmission, or if not received, contacted the paramedic unit and the department's nurse educator to identify and resolve the problem. Per system-wide protocol, paramedics transmit all ECGs with interpretation of STEMI. Receiving hospitals submit patient data to a single registry as part of ongoing system quality improvement. The frequency of successful ECG transmission and time to intervention (FMC2B and D2B times) in the 18 months following implementation was compared to the 10 months prior. Post-implementation, the time the ECG transmission was received was also collected to determine the transmission gap time (time from ECG acquisition to ECG transmission received) and the advanced notification time (time from ECG transmission received to patient arrival).

RESULTS

There were 388 patients with field ECG interpretations of STEMI, 131 pre-intervention and 257 post-intervention. The frequency of successful transmission post-intervention was 73% compared to 64% prior; risk difference (RD)=9%; 95% CI, 1-18%. In the post-intervention period, the median FMC2B time was 79 minutes (inter-quartile range [IQR]=68-102) versus 86 minutes (IQR=71-108) pre-intervention (P=.3) and the median D2B time was 59 minutes (IQR=44-74) versus 60 minutes (IQR=53-88) pre-intervention (P=.2). The median transmission gap was three minutes (IQR=1-8) and median advanced notification time was 16 minutes (IQR=10-25).

CONCLUSION

Implementation of weekly test ECG transmissions was associated with improvement in successful real-time transmissions from field to hospital, which provided a median advanced notification time of 16 minutes, but no decrease in FMC2B or D2B times. D'ArcyNT, BossonN, KajiAH, BuiQT, FrenchWJ, ThomasJL, ElizarrarazY, GonzalezN, GarciaJ, NiemannJT. Weekly checks improve real-time prehospital ECG transmission in suspected STEMI. Prehosp Disaster Med. 2018;33(3):245-249.

False Positive STEMI Activations in a Regional Network: Comprehensive Analysis and Clinical Impact. Results From the Catalonian Codi Infart Network

INTRODUCTION AND OBJECTIVES

ST-segment elevation myocardial infarction (STEMI) network activation by a noncardiologist reduces delay times but may increase the rate of false-positive STEMI diagnoses. We aimed to determine the prevalence, predictors, and clinical impact of false-positive activations within the Catalonian STEMI network (Codi Infart).

METHODS

From January 2010 through December 2011, all consecutive patients treated within the Codi Infart network were included. Code activations were classified as appropriate if they satisfied both electrocardiogram and clinical STEMI criteria. Appropriate activations were classified as false positives using 2 nonexclusive definitions: a) "angiographic" if a culprit coronary artery was not identified, and b) "clinical" if the discharge diagnosis was other than STEMI.

RESULTS

In total, 5701 activations were included. Appropriate activation was performed in 87.8% of the episodes. The rate of angiographic false positives was 14.6%, while the rate of clinical false positives was 11.6%. Irrespective of the definition, female sex, left bundle branch block, and previous myocardial infarction were independent predictors of false-positive STEMI diagnoses. Using the clinical definition, hospitals without percutaneous coronary intervention and patients with complications during the first medical contact also had a false-positive STEMI diagnoses rate higher than the mean. In-hospital and 30-day mortality rates were similar for false-positive and true-positive STEMI patients after adjustment for possible confounders.

CONCLUSIONS

False-positive STEMI diagnoses were frequent. Outcomes were similar for patients with a true-positive or false-positive STEMI diagnosis treated within a STEMI network. The presence of any modifiable predictors of a false-positive STEMI diagnosis warrants careful assessment to optimize the use of STEMI networks.

Risk score to predict false-positive ST-segment elevation myocardial infarction in the emergency department: a retrospective analysis

Background

The best treatment approach for ST-segment elevation myocardial infarction (STEMI) is prompt primary percutaneous coronary intervention (PCI). However, some patients show ST elevation on electrocardiography (ECG), but do not have myocardial infarction. We sought to identify the frequency of and to develop a prediction model for false-positive STEMI.

Methods

This study was conducted in the emergency departments (EDs) of two hospitals using the same critical pathway (CP) protocol to treat STEMI patients with primary PCI. The prediction model was developed in a derivation cohort and validated in internal and external validation cohorts.

Results

Of the CP-activated patients, those for whom ST elevation did not meet the ECG criteria were excluded. Among the patients with appropriate ECG patterns, the incidence of false-positive STEMI in the entire cohort was 16.3%. Independent predictors extracted from the derivation cohort for false-positive STEMI were age < 65 years (odds ratio [OR], 2.54; 95% confidence interval [CI], 1.35–4.89), no chest pain (OR, 12.04; 95% CI, 5.92–25.63), atypical chest pain (OR, 7.40; 95% CI, 3.27–17.14), no reciprocal change (OR, 4.80; 95% CI, 2.54–9.51), and concave-morphology ST elevation (OR, 14.54; 95% CI, 6.87–34.37). Based on the regression coefficients, we established a simplified risk score. In the internal and external validation cohorts, the areas under the receiver operating characteristic curves for our risk score were 0.839 (95% CI, 0.724–0.954) and 0.820 (95% CI, 0.727–0.913), respectively; the positive predictive values were 40.9% and 22.0%, respectively; and the negative predictive values were 94.9% and 96.7%, respectively.

Discussion

Our prediction model would help them make rapid decisions with better rationale.

Conclusion

We devised a model to predict false-positive STEMI. Larger-scale validation studies are needed to validate our model, and a prospective study to determine whether this model is effective in reducing improper primary PCI in actual clinical practice should be performed.

Outcomes by Mode of Transport of ST Elevation MI Patients in the United Arab Emirates

INTRODUCTION

The purpose of this multicenter study was to assess differences in demographics, medical history, treatment times, and follow-up status among patients with ST-elevation myocardial infarction (STEMI), who were transported to the hospital by emergency medical services (EMS) or by private vehicle, or were transferred from other medical facilities.

METHODS

This multicenter study involved the collection of both retrospective and prospective data from 455 patients admitted to four hospitals in Abu Dhabi. We collected electronic medical records from EMS and hospitals, and conducted interviews with patients in person or via telephone. Chi-square tests and Kruskal-Wallis tests were used to examine differences in variables by mode of transportation.

RESULTS

Results indicated significant differences in modes of transportation when considering symptom-onset-to-balloon time (p < 0.001), door-to-balloon time (p < 0.001), and health status at six-month and one-year follow-up (p < 0.001). Median times (interquartile range) for patients transported by EMS, private vehicle, or transferred from an outside facility were as follows: symptom-onset-to-balloon time in hours, 3.1 (1.8-4.3), 3.2 (2.1-5.3), and 4.5 (3.0-7.5), respectively; door-to-balloon time in minutes, 70 (48-78), 81 (64-105), and 62 (46-77), respectively. In all cases, EMS transportation was associated with a shorter time to treatment than other modes of transportation. However, the EMS group experienced greater rates of in-hospital events, including cardiac arrest and mortality, than the private transport group.

CONCLUSION

Our results contribute data supporting EMS transportation for patients with acute coronary syndrome. Although a lack of follow-up data made it difficult to draw conclusions about long-term outcomes, our findings clearly indicate that EMS transportation can speed time to treatment, including time to balloon inflation, potentially reducing readmission and adverse events. We conclude that future efforts should focus on encouraging the use of EMS and improving transfer practices. Such efforts could improve outcomes for patients presenting with STEMI.

Incidence and characteristics of inappropriate and false-positive cardiac catheterization laboratory activations in a regional primary percutaneous coronary intervention program

BACKGROUND

The implementation of regional primary percutaneous coronary intervention (PCI) programs has been critical in achieving timely intervention in patients with ST-segment elevation myocardial infarction (STEMI). However, 1 consequence has been inappropriate and false-positive cardiac catheterization laboratory (CCL) activations where either angiography is cancelled or no culprit lesion is found, respectively.

METHODS

We performed a retrospective cohort study of 1,391 patients referred for primary PCI to a single academic center from November 2007 to August 2013. Our purpose was to determine the incidence and characteristics of inappropriate and false-positive CCL activations by emergency departments (EDs) or emergency medical services (EMS), and the effect of a quality improvement (QI) initiative to reduce such events implemented during this period.

RESULTS

During the study period, there were 37 (2.7%) inappropriate and 206 (14.8%) false-positive CCL activations. There was no difference between the ED and EMS rates of inappropriate activation (2.1% vs 3.8%, P = .06). Among patients who proceeded to angiography, the false-positive rate for ED CCL activation was 16.9% compared to 11.5% for EMS (P = .01). Although there was no difference comparing inappropriate activation or false-positive rates before and after the QI initiative (P = .22), we observed an encouraging year-to-year trend.

CONCLUSIONS

Emergency department activation of the CCL is associated with a higher false-positive rate than activation by EMS. Further QI efforts are required to improve communication between interventional cardiologists, emergency physicians, and paramedics to improve the specificity of CCL activation while taking care not to sacrifice sensitivity and rapidity of diagnosis.