Regional Centers of Excellence for the Care of Patients With Acute Ischemic Heart Disease

Intoduction

The rapid restoration of normal coronary blood flow via pharmacologic and/or mechanical recanalization of an occluded coronary artery limits the extent of myocardial necrosis and reduces mortality of patients who present with ST-elevation myocardial infarction (STEMI). Furthermore, primary percutaneous coronary intervention (PPCI) has demonstrated more frequent, complete, and durable coronary reperfusion in both randomized controlled trials (RCTs) and observational studies when compared to thrombolysis with medical therapy alone and is the preferred revascularization modality for treating STEMI by current guidelines if PPCI can be provided in a prompt, expert manner. In light of this, current American College of Cardiology Foundation (ACCF)/American Heart Association (AHA) guidelines recommend emergency medical services (EMS) transport directly to a percutaneous coronary intervention (PCI)-capable hospital for PPCI as the recommended strategy for STEMI patients, with an ideal first medical contact to PCI device-time system goal of 90 minutes or less (class I, level of evidence B). Mounting data also supports the idea of complete coronary revascularization in patients with acute coronary syndromes (ACS). However, a concerted, integrated approach to caring for patients with ACS, particularly those in cardiogenic shock and out-of-hospital cardiac arrest (OHCA), has been complicated by the diversity and extent of resources required for comprehensive treatment and by the various settings (urban, suburban, rural) in which care is delivered. Data from national registries have demonstrated a failure to achieve recommended system goals, particularly among STEMI patients who presented to hospitals without PCI capability and required interhospital transfer for PPCI. The creation of specialized care centers for other medical emergencies, such as trauma and acute stroke, has been shown to improve clinical outcomes; therefore the concept of developing regional centers of excellence for the care of ACS (including STEMI), cardiogenic shock, and OHCA has become the focus of a collaborative initiative of the AHA and the ACCF as well as individual states.

The term regional implies meaningful networking associations between all prehospital and hospital-based constituents that enable rapid recognition and timely care delivery in an integrated fashion. These initiatives have been in part prompted by studies that demonstrate shortfalls in the achievement of quality-ensured, guideline-compliant care in addition to disparities in treatment on the basis of age, sex, race, geographic location, or time of STEMI presentation. Similarly, hospitals with a higher proportion of transfer-in non–ST-elevation myocardial infarction (NSTEMI) patients tend to provide higher overall quality of care with lower overall in-hospital mortality, though the proportion of NSTEMI patients transferred into revascularization-capable hospitals varies significantly as shown in the CRUSADE (Can Rapid Risk Stratification of Unstable Angina Patients Suppress Adverse Outcomes With Early Implementation of the ACC/AHA Guidelines) National Quality Improvement Initiative.

Through focus on system process components, multiple national initiatives such as Get With The Guidelines (GWTG), the Guidelines Applied to Practice (GAP) project, the National Registry of Myocardial Infarction (NRMI), the CRUSADE registry, and the D2B (door-to-balloon) Alliance have demonstrated a positive impact as reflected by increased clinical practice guideline (CPG) adherence for early (≤24 hours) and predischarge medical therapies and a reduction in D2B and door-to-needle (D2N) times, as well as door-in–door-out (DIDO) times, for STEMI patients who require interhospital transfer. Nevertheless, broader and more region-specific system-based initiatives such as Mission: Lifeline continue to be vital in reducing total ischemic time—that is, time from chest pain symptom onset to coronary recanalization—which is the principal determinant of outcome. Any delay in reperfusion (i.e., prolongation of total ischemic time) is associated with higher short-term (in-hospital, 30-day) and late (1-year) mortality in a continuous, nonlinear fashion ( Fig. 37.1 ). Because only a minority of U.S. hospitals are capable of performing PCI, the provision of prompt, expert PCI as the preferred reperfusion modality for the majority of ACS patients is a formidable challenge that will ultimately require regional integration of resources. Not surprisingly, a very similar relationship can be seen between clinical volume and outcomes with cardiogenic shock, given that it is a complex acute condition that requires a multidisciplinary treatment team to provide procedural, surgical, and medical care. A study from the Nationwide Inpatient Sample illustrated this direct relationship between adjusted in-hospital mortality and hospital volume. The adjusted hazard ratio (HR) for mortality in the lowest quartile (<27 cases of cardiogenic shock treated per year) was 1.27 (1.15, 1.40) compared to the highest quartile (≥107 cases of cardiogenic shock treated per year). Therefore, establishing systems of care with higher-volume hospitals utilized as regional hubs integrated with clearly defined protocols for management of cardiogenic shock for all ACSs including STEMI and OHCA has the potential to improve patient outcomes.

The Case for Regionalized Care

Based in part on experience with trauma and stroke care in the United States, several basic tenets form the foundation of the premise behind regionalized systems for ACS, cardiogenic shock, and OHCA, including observations that (1) annual procedural volumes are directly related to clinical outcomes, (2) medical resources are limited, and (3) regionalization facilitates CPG adherence, quality, and outcomes monitoring, along with access to advanced technology and expertise.

A direct relationship has been demonstrated between both hospital facility and physician operator annual procedural volumes and optimal clinical outcomes following either elective or primary PCI and coronary artery bypass graft (CABG) surgery. Physicians and hospitals with the highest procedure volumes have lower risk-adjusted in-hospital mortality to the extent that the relative benefit of PPCI versus fibrinolysis for the treatment of STEMI may be lost when PPCI is performed in a low-volume institution. Similarly, risk-adjusted hospital mortality was increased (HR 1.20; 95% confidence interval [CI] 1.08 to 1.33) among centers that perform in the lowest tertile of annual PPCI volumes (<36 procedures/year) when compared with those in the highest tertile (>60 procedures/year). A pooled analysis of multiple studies that included over one million PCI procedures confirmed the relationship between lower annual hospital PCI volumes (≤200 cases) with an increase in in-hospital mortality and need for emergent CABG surgery following PCI. These specific data on annual institutional volume and outcome have been acknowledged by both the ACCF/AHA/Society for Cardiovascular Angiography and Interventions (SCAI) 2013 Update of the Clinical Competence Statement on Coronary Artery Interventional Procedures and the SCAI/ACC/AHA 2014 Expert Consensus Document regarding PCI without on-site surgical backup as follows: “It is important to note that a signal exists suggesting that an institutional volume threshold [below] 200 PCI/year appears to be consistently associated with worse outcomes across various studies.” The Clinical Competence Statement then continues, “Accordingly, the writing committee recommends that an institution without on-site surgery with a volume fewer than 200 PCI annually, unless in a region underserved because of geography, should strongly consider whether or not it should continue to offer this service.”

A similar PCI volume–outcome (in-hospital mortality) relationship has been demonstrated for physician operators by the New York statewide database for PPCI and by the National Cardiovascular Data Registry (NCDR) for both elective and acute PCI ( Fig. 37.2 ). In-hospital mortality was increased for elective PCI (HR 1.27; 95% CI 1.11 to 1.45) and acute PCI (HR 1.10; 95% CI 1.00 to 1.21 among physician operators who performed fewer than 75 PCIs per year (vs. ≥75 PCIs/year). Similar results were reproduced recently from the NCDR in 2017, showing that the median annual number of procedures performed per operator was 59, with 44% of operators performing <50 PCI procedures per year. This study showed that low-volume operators more frequently performed emergent PPCI procedures and practiced at hospitals with lower annual PCI volumes. This is important because 26% of all centers that report to the NCDR performed fewer than 200 PCIs per year, and 38% performed fewer than 36 PCIs per year. The adjusted risk of in-hospital mortality was higher for PCI procedures performed by low- and intermediate-volume operators compared with those performed by high-volume operators (see Fig. 37.2 ).

Despite these data showing a direct correlation between operator volume and outcomes, both the 2013 Clinical Competency Statement and the 2014 Expert Consensus Document allow for lower annual PCI volumes (≥50 total PCI and ≥ 11 PPCI/year) for credentialing. Considering the declining number of PCI procedures performed annually in the United States, the increasing complexity of coronary artery disease (CAD), and the need for medical cost reduction while maintaining or increasing quality, a more reasonable approach might be to promote regionalization, with fewer institutions providing PCI, allowing operators to maintain higher annual volume and thus optimize care delivery.

Furthermore, the case for regionalization extends beyond the care delivered in the cath lab. Each of the process of care metrics for ACS patients as measured by ACC/AHA guideline adherence has been linked to both in-hospital and late (6- to 12-month) survival following presentation of ACS. An analysis of hospital composite guideline adherence quartiles demonstrated an inverse relationship between the adherence to guideline-compliant care and the risk-adjusted in-hospital mortality rate. For every 10% increase in guideline adherence, a 10% relative reduction in in-hospital mortality was observed. This observation supports the central hypothesis that better adherence with evidence-based care practices throughout the scope of patient care for patients with ACS will result in better outcomes. Additionally, lower-volume small community hospitals may be less likely to allocate the capital resources and personnel required to adequately track, collate, and report clinical outcomes or process measures (i.e., guideline compliance). Indeed, in a survey commissioned by the AHA, only slightly more than half of the hospitals queried were systematically tracking STEMI treatment times (D2N or D2B times) or rates of infection, readmission, stroke, recurrent myocardial infarction (MI), or mortality following either PCI or CABG. This observation is made more meaningful by the fact that multiple national initiatives—such as GWTG, the Cardiac Hospitalization Atherosclerosis Management Program (CHAMP), the GAP project, the NRMI, and the CRUSADE Acute Coronary Treatment and Intervention Outcomes Network (ACTION) registry—have recently placed emphasis on system quality through systematic measurement of both care processes and clinical outcomes.

The D2B Alliance was initiated in November of 2006 and has resulted in increased use of recommended strategies for process improvement and a greater number of patients being treated within guideline recommendations. Despite documented process improvement as reflected by progressive reduction in D2B times, concurrent improvement in mortality following PPCI appears to have plateaued, and focus has now turned toward total ischemic time as the principal determinant of outcomes. Because the relationship between total ischemic time and the extent of myocardial necrosis is nonlinear ( Fig. 37.3 ), even optimally short D2B times may have little impact on the degree of myocardial salvage or survival in patients who present to the hospital late following infarct symptom onset. Furthermore, because of a lack of integrated systems for STEMI care, patients who require transfer from non–PCI-capable facilities for PPCI continue to experience long door-to-door-to-balloon (D2D2B) times, as well as total ischemic times, with consequent poorer clinical outcomes. This trend is also seen for patients presenting with NSTEMI who require transfer for definitive revascularization compared to those presenting to hospitals with on-site access to the full spectrum of resources required to care for this group. Multiple factors including worse clinical outcomes, decreased ability to track and report clinical metrics, inability to adequately manage patients with complications of ACS, including cardiogenic shock and OHCA, and incomplete longitudinal care continue to provide strong evidence for the regionalization of care for patients with ACS.