Highlights
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4-step STEMI protocol improved care in patients with nonsystem delays.
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Protocol reduced door-to-balloon time from 132 to 101 minutes.
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Rates of bleeding, shock, and AKI significantly declined postimplementation.
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Discharge to home improved without increase in in-hospital mortality.
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Findings challenge view that nonsystem delays are unmodifiable in STEMI.
Hospital-wide strategies improve outcomes in STEMI, yet their impact on patients with nonsystem delays (NSD) to primary PCI remains unknown. This study evaluated the effect of a 4-step comprehensive STEMI protocol (CSP) on outcomes in this high-risk population. This observational cohort analysis included STEMI patients with NSD as defined by the ACC National Cardiovascular Data Registry CathPCI Registry v5.0 criteria, which included difficult vascular access, difficulty crossing the culprit lesion, cardiac arrest and/or need for intubation before PCI, patient delays in providing consent for PCI, emergent placement of left-ventricular support device before PCI, and other reasons. Process and outcome metrics were compared before (January, 2011–July, 2014; n = 163) and after (July, 2014–July, 2019; n = 196) CSP implementation. The CSP comprised: (1) emergency department catheterization-laboratory activation; (2) STEMI Safe Handoff Checklist; (3) immediate transfer to an available laboratory; and (4) radial-first PCI. Among 359 patients with NSD, CSP implementation increased pre-PCI guideline-directed medical therapy (57.1%–79.6%, p <0.001) and radial access (16.6%–55.6%, p <0.001), and reduced median door-to-balloon time (132–101 minutes, p = 0.001). Post-CSP patients experienced lower rates of bleeding (22.7%–10.2%, p = 0.002), cardiac arrest (36.2%–23.5%, p = 0.01), circulatory shock (39.9%–24.5%, p = 0.003), and acute kidney injury (30.7%–19.9%, p = 0.03), with more frequent discharge to home (65.0%–78.6%, p = 0.006). In-hospital mortality was similar (14.1% vs 9.2%, p = 0.20). In conclusion, a 4-step CSP improved process metrics and clinical outcomes among STEMI patients with NSD, challenging the notion that outcomes of NSD cohort are unmodifiable and underscoring the importance of system-based interventions in this high-risk cohort.
Immediate reperfusion via primary percutaneous coronary intervention (PCI) is the mainstay of treatment in patients presenting with ST-segment elevation myocardial infarction (STEMI). ,, This emphasis on rapid intervention reflects the well-known dictum that “time is muscle,” a principle that has been supported robustly by multiple studies demonstrating that incremental delays in door-to-balloon time (D2BT) negatively impact short and long-term clinical outcomes. ,,,, Consequently, there has been a concerted field-wide effort to achieve mechanical reperfusion within the guideline-recommended 90-minute window for STEMI patients presenting to PCI-capable hospitals. ,,,,,
Quality improvement initiatives have focused on alleviating system-based delays in STEMI care. However, despite advancements in the diagnosis and management of STEMI, a notable proportion of patients continue to encounter “unavoidable” delays, termed nonsystem delays (NSD), in STEMI care. Nearly two-thirds of STEMI patients with NSD fail to meet goal D2BT due to difficult vascular access, difficulty crossing the culprit lesion, cardiac arrest and/or need for intubation before PCI, patient delays in providing consent for PCI, emergent placement of left-ventricular support device before PCI, and other reasons. , The concept of NSD was initially introduced as an exclusion criterion from quality metrics reporting by the Centers for Medicare and Medicaid Services (CMS) in 2005 and was further expanded in 2006. , This exclusion sought to prevent the penalization of hospitals which treated disproportionately sicker patients or managed clinical scenarios beyond their standard processes of care. In 2009, the American College of Cardiology-National Cardiovascular Data Registry (ACC NCDR) expanded on this framework by tracking “nonsystems reasons for delay in PCI” for patients undergoing primary PCI for STEMI. , While initially regulatory in nature, the concept of NSD has traditionally been poorly understood. Granular investigations into these patients from the ACC NCDR have allotted a deeper understanding of the clinical implications and complexities associated with STEMI patients with NSD. It has been observed that NSD represent a high-risk cohort within the STEMI population. , Patients with NSD often present with complex clinical scenarios and experience higher rates of adverse outcomes, including increased in-hospital mortality, cardiogenic shock, heart failure, and other postprocedure complications. Further, patients with NSD are also more likely to be elderly, female, and Black. These associations underscore the critical need to address these delays not simply as a reporting metric but importantly as a key aspect to improve patient care and outcomes. No studies to date address whether systems-level interventions can effectively improve outcomes in this particularly high-risk cohort. Our study aims to assess the impact of a comprehensive 4-step STEMI protocol on process metrics and clinical outcomes of STEMI patients encountering NSD.
Methods
Study population and data collection
This observational cohort study involved consecutive patients who presented with STEMI and received primary PCI treatment at a tertiary care hospital within a multihospital regional health system from January 01, 2011 to July 15, 2019. Data were collected prospectively as part of our institutional reporting to the ACC NCDR CathPCI Registry. On July 15, 2014, our health system implemented a comprehensive STEMI protocol (CSP) designed to standardize STEMI care. This study evaluated the impact of this CSP on STEMI patients with NSD to primary PCI. NSD were defined according to the ACC NCDR CathPCI Registry v4.4 and v5.0 Coder’s Data Dictionary as patient-centered reasons for delay and included difficult vascular access, difficulty crossing the culprit lesion, cardiac arrest and/or need for intubation before PCI, patient delays in providing consent for PCI, emergent placement of left-ventricular support device before PCI, and “other” unspecified reasons. Difficult vascular access is defined as when the patient’s anatomy is torturous, obstructive or otherwise prohibitive to the vascular access device; importantly, this definition does not apply if the operator is unable to gain access due to inexperience or device selection, etc. Similarly, difficulty crossing the culprit lesion is defined as when the patient’s anatomy is torturous, obstructive or otherwise prohibitive to guidewire or device access, however, this definition does not apply if the operator is unable to cross the culprit lesion due to inexperience or device selection, etc. Instances where the patient and/or their condition is obstructive to the timing of PCI were included as “Other” reason for NSD. These include transport delay, unclear diagnosis, consultation from MD/family, and difficult coronary anatomy.
This study was composed of 2 groups: the control (preprotocol) group and the protocol group ( Figure 1 ). The control group included 163 STEMI patients with NSD who were treated between January 01, 2011 and July 07, 2014, and the protocol group consisted of 196 STEMI patients with NSD treated from July 15, 2014 to July 15, 2019. Figure 1 illustrates the prevalence of NSD reasons across both groups. This study was conducted with the approval of the Cleveland Clinic Institutional Review Board, and informed consent was waived.
Patient selection flowchart and proportions of reasons for nonsystem delays. Among 1,847 patients who presented with STEMI and underwent PCI from January 01, 2011 and July 15, 2019, a total of 365 patients experienced nonsystem delays. Of these, 6 patients were excluded due to insufficient data and to maintain the integrity of data analysis implemented. Abbreviations: CSP = comprehensive STEMI protocol; PCI = percutaneous coronary intervention; STEMI = ST-segment elevation myocardial infarction.
4-step comprehensive STEMI protocol
The study was conducted at the Cleveland Clinic Main Campus hospital, a 1,437-bed quaternary care center with 24/7/365 primary PCI capability. This STEMI network comprises 10 Cleveland Clinic hospitals and 3 free-standing emergency departments (ED) within a 60-mile radius, facilitating a robust interfacility transfer protocol for STEMI patients as previously published. ,,,,
The study compared 2 distinct methodologies for STEMI care which delineated patient cohorts based on the implementation timeline of the CSP. The control group, defined by STEMI patients treated from January 01, 2011 to July 14, 2014, followed traditional protocols for cardiac catheterization lab activation, requiring a joint decision-making process between the ED physician, on-call cardiology fellow, and cardiac catheterization lab physician. Initial triage and management, including guideline-directed medical therapy (GDMT) administration, varied according to the expertise and preference of the treating physician. Patient transfer to the cardiac catheterization lab was contingent upon lab readiness. The choice of vascular access for primary PCI was operator dependent.
In contrast, on July 15, 2014, the CSP was implemented, which introduced significant process changes aimed at minimizing care variability and improving patient outcomes as previously described. ,,, STEMI patients treated between July 15, 2014 and July 15, 2019 formed the protocol group. The protocol included the following key modifications:
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Streamlining cardiac catheterization lab activation by enabling direct activation by ED physicians which bypassed the need for initial cardiology consultation.
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Standardizing early triage and management of STEMI patients, including uniform GDMT administration, by implementing a “STEMI Safe Handoff Checklist.” This checklist outlined the roles of ED and cardiology teams, provided GDMT guidelines, and alerted the catheterization lab team of the risk factors for PCI-related complications.
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Instituting an immediate transfer policy to an always-ready cardiac catheterization lab, thereby minimizing patient delays.
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Transitioning to a radial-first approach for primary PCI, while allowing operators to determine the optimal access site for each individual patient.
These steps were complemented by existing institutional strategies established to improve D2BT performance, , including the use of prehospital electrocardiograms, a streamlined catheterization lab activation system, the presence of in-house cardiology fellows and catheterization laboratory nurses, continuous monitoring of performance data, and interdisciplinary collaboration between ED and cardiology providers.
Study outcomes
Process metrics and clinical outcomes were compared between the control group and protocol group. Process outcomes included administration of pre-PCI GDMT, use of radial access for PCI, D2BT, fluoroscopy and contrast dose used during the procedure, and use of mechanical circulatory support. Pre-PCI GDMT was recorded as the administration of aspirin, a P2Y12 inhibitor (clopidogrel, prasugrel, or ticagrelor), and an anticoagulant (low-molecular-weight heparin, unfractionated heparin, or bivalirudin) prior to the procedure. D2BT was defined per ACC NCDR standards as the time from patient arrival to the ED to first device activation during PCI. Goal D2BT was defined per society guidelines as ≤90 minutes for in-hospital STEMI or patient presenting to the main campus ED (a PCI-capable facility). For patients being transferred from a non-PCI-capable facility, the goal D2BT was ≤120 minutes.
Clinical outcomes included net adverse clinical events (NACE: composite of MACCE and bleeding), bleeding incidents, cardiac arrest, circulatory shock, acute kidney injury, major adverse cardiovascular and cerebrovascular events (MACCE: composite of death, reinfarction, stroke, and cardiogenic shock), stroke, discharge to home, and in-hospital mortality. All outcomes were defined per the ACC NCDR CathPCI Registry and extracted by trained data abstractors.
Statistical analysis
Continuous variables are presented as median [interquartile range] (IQR) and were compared using Wilcoxon rank-sum test. Categorical data are reported as frequencies (percentages) and were compared using Chi-squared or Fisher’s exact tests. Kaplan–Meier time-to-event analyses and the log-rank test were utilized to compare survival probability between the 2 groups. Mortality status and last known date of survival were collected from the electronic medical records. Hospital discharge date or death date, if the patient died during the index hospitalization, was used as the censor date in assessing in-hospital mortality. Violin charts were created to depict differences in D2BT between groups. Bar charts were developed using Graph pad prism version 8 to compare key process metrics and clinical outcomes. P-value <0.05 was used to assess for statistical significance. All analyses were performed using R version 3.6.3.
Results
Baseline characteristics
Among 1,874 patients who developed STEMI and underwent PCI between January 01, 2011 and July 15, 2019, 365 patients experienced NSD ( Figure 1 ). Of these, 6 patients were excluded due to incomplete baseline and follow-up data. A total of 163 patients (control group) presented before and 196 patients (protocol group) presented after implementation of the 4-step CSP. Amongst the control group, 97 (59.5%) patients were transferred from outside facilities and 66 (40.5%) patients presented to the PCI facility. Similarly, amongst protocol group, 112 (57.1%) patients were transferred from outside facilities and 84 (42.9%) patients presented to the PCI facility. Table 1 demonstrates the baseline characteristics of both groups. The control group had lower body mass index (median 27.8 kg/m 2 vs 29.39 kg/m 2, p = 0.02) and a higher rate of previous myocardial infarction (40.5% vs 26.5%, p = 0.007) relative to the protocol group. Otherwise, the study groups had similar baseline characteristics including age, sex, smoking status, and rates of hypertension, chronic kidney disease, cerebrovascular disease, chronic obstructive pulmonary disease, diabetes mellitus, peripheral arterial disease, previous PCI, previous coronary artery bypass grafting, and heart failure ( Table 1 ).
Table 1
Baseline characteristics of STEMI patients with NSD before (control group) and after (protocol group) implementation of a 4-step CSP.
| Variable | Control group ( n = 163) | Protocol group ( n = 196) | p-value |
|---|---|---|---|
| Age (years) | 64.0 [53.0, 73.0] | 64.0 [53.8, 74.0] | 0.97 |
| Male sex | 97 (59.5%) | 123 (62.8%) | 0.60 |
| Body mass index (kg/m 2) | 27.8 [24.8, 32.2] | 29.4 [25.7, 33.7] | 0.02 |
| Black race | 41 (25.2%) | 63 (32.1%) | 0.18 |
| Co-morbidities | |||
| Smoker | 62 (38.0%) | 94 (48.0%) | 0.08 |
| Hypertension | 131 (80.4%) | 155 (79.1%) | 0.87 |
| Hyperlipidemia | 126 (77.3%) | 151 (77.0%) | 1.00 |
| Chronic kidney disease | 53 (32.5%) | 61 (31.1%) | 0.87 |
| Cerebrovascular disease | 27 (16.6%) | 31 (15.8%) | 0.96 |
| COPD | 17 (10.4%) | 27 (13.8%) | 0.42 |
| Diabetes mellitus | 53 (32.5%) | 71 (36.2%) | 0.53 |
| Peripheral arterial disease | 28 (17.2%) | 29 (14.8%) | 0.64 |
| Prior myocardial infarction | 66 (40.5%) | 52 (26.5%) | 0.007 |
| Prior PCI | 38 (23.3%) | 59 (30.1%) | 0.19 |
| Prior CABG | 17 (10.4%) | 17 (8.7%) | 0.70 |
| Heart failure | 29 (17.8%) | 48 (24.5%) | 0.16 |
| Presenting location | 0.84 | ||
| Main campus ED | 42 (25.8%) | 56 (28.6%) | |
| Transfer from non-PCI facility | 97 (59.5%) | 112 (57.1%) | |
| In-hospital | 24 (14.7%) | 28 (14.3%) |
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