Acute Coronary Syndrome in North America




A large number of patients with acute coronary syndrome (ACS) are not given therapies that can save lives and prevent recurrent cardiac events. Analyses of trends over the last decade from the U.S. National Registry of Myocardial Infarction (NRMI) have shown a 23% reduction in risk of hospital mortality from acute myocardial infarction. This change has occurred because of aggressive risk factor modification and improvement in pharmacologic and interventional treatments. , However, despite clear evidence about the proven benefits of these therapies, there is concern regarding suboptimal adherence to guideline recommendations in clinical practice. Thus, significant efforts are being made currently to monitor the quality of care and adherence to evidence-based guidelines in patients with ACS to improve clinical outcomes. This chapter will review the current prevalence of ACS in North America, gaps in treatment, and initiatives to improve safety and outcomes in these patients by the development of large national registries.


According to the American Heart Association (AHA) statistics, 1.4 million patients in the United States are hospitalized annually for ACS. , From 1990 to 2006, of all patients with acute myocardial infarction (AMI), the proportion with non–ST-segment elevation myocardial infarction (NSTEMI) increased exponentially from 14.2% to 59.1% ( Fig. 5-1 ). Possible explanations for this include adoption of serum troponin as a sensitive biomarker for diagnosing AMI in the mid- to late 1990s, increased use of medical therapy, and coronary revascularization, measures that could have led to early detection of AMI and prevented the transition from NSTEMI to ST-segment elevation myocardial infarction (STEMI) in some patients. There has also been a change in the demographics of patients with ACS. Clinicians are now faced more frequently with higher risk patients of increasing age and with multiple comorbidities, including heart failure, stroke, diabetes, hypertension, and previous coronary revascularization. Over the last decade, the mean age of presentation with AMI has risen from 65.3 to 68.0 years, and the proportion of women has increased from 35.3% to 39.3%.




FIGURE 5–1


Trends of STEMI and NSTEMI in NRMI Registry (1990-2006). A, Proportion of patients in NRMI-1 to NRMI-5 classified as having STEMI or NSTEMI, and proportion of patients in whom troponin assay was used to diagnose AMI. B and C, Proportion of patients with STEMI and NSTEMI, respectively, stratified by age (years; P = .0001 for all).


Morbidity and mortality after ACS remain substantial. Within the next 5 years, recurrent myocardial infarction will occur in up to 32% of patients, heart failure in 29%, stroke in 17%, and sudden cardiac death in 1% to 15%. , The African American population has the highest risk for these events. Events also tend to occur more commonly in women and older adults.


In randomized clinical trials (RCTs), the in-hospital mortality rates have been reported to be approximately 2% from NSTEMI and from 3% to 5% in patients with STEMI. Interestingly, however, clinical registries report higher rates of in-hospital mortality, approximately 5% to 7% for NSTEMI and 7% to 9% for STEMI. This discrepancy is likely related to the delivery of better medical care and exclusion of higher risk patients in RCTs. Long-term mortality, conversely, is higher in patients with NSTEMI than in those with STEMI. This is related to a higher risk patient profile, including frequent multivessel disease, more jeopardized myocardium, and a greater concurrent risk of both recurrent ischemia and reinfarction in those with NSTEMI.


Gaps in Acute Coronary Syndrome Treatment


Recent studies have documented substantial gaps between evidence-based recommendations and clinical management of patients with ACS. A disturbing trend has been noticed in the analyses of various clinical registries, suggesting that the highest risk patients with ACS are paradoxically treated less aggressively. Treatment patterns from the NRMI registry that included more than 1.9 million patients showed a 24% risk reduction in early mortality from STEMI and a 23% reduction in early mortality from NSTEMI by practicing evidence-based therapies. Similarly, a recent registry of patients with non–ST-segment elevation (NSTE) ACS treated at 350 U.S. hospitals has found that adherence to American College of Cardiology (ACC)–AHA guidelines led to a reduction in absolute in-hospital mortality from 6.3% to 4.1%. However, despite these benefits, up to 25% of opportunities to provide the guideline-recommended care were missed in these patients. ,


To ensure that patients with ACS benefit from these proven therapies, the ACC-AHA have published evidence-based treatment guidelines that provide a consensus—or standard of care—for the diagnostic or therapeutic interventions appropriate for most patients in most circumstances. These guidelines also provide a method for measuring the quality of cardiovascular care provided by individual institutions, or performance measurement. These performance measures have been used to determine hospital referral patterns, public reporting, reimbursement, and maintaining institutional accreditation.




Real-World Acute Coronary Syndrome Registries in North America


Although most clinical practice guidelines in cardiology are based on information obtained from RCTs, guideline writers are sometimes hampered by not having enough information about the real-world practice patterns at a given time. Recently, several registries have been created in the United States and globally to collect information regarding treatment of ACS patients ( Table 5-1 ). These registries function complementary to RCTs by providing information about real-world patients who are generally higher risk and may have been excluded in the RCTs.



TABLE 5–1

Acute Coronary Syndrome Registries in North America




























































Registry Centers Included Timeline Design Type of Registry Outcomes
CHAMP (Cardiac Hospitalization Atherosclerosis Management Program) Single center, at UCLA 1994-1995 Initiate pharmacologic therapy and lifestyle modification during hospital admission ACS and ischemic heart failure, 302 patients and 256 controls Increased use of aspirin, beta blockers, ACE inhibitors, and statins at discharge; reduction in 1-yr mortality (7.0% vs. 3.3%) and AMI (7.8% vs. 3.1%)
GWTG (Get With the Guidelines) Nationwide, multicenter, AHA initiative


  • 2000-2001 (pilot project)



  • 2000-2009 (national initiative)

Internet-based tool to improve management, compliance; used teachable moment concept AMI; 1738PilotNational-CAD >250,000 Improved adherence to pharmacologic therapy and smoking cessation for secondary prevention of CAD
GAP (Guidelines Applied in Practice) 10 health systems in Michigan 1998-2000 Improve guideline adherence by providing toolkit of standard orders and forms AMI; ≈400 Medicare patients Decreased 1-yr mortality with use of GAP tool-kit
NRMI (National Registry of Myocardial Infarction) Nationwide, 1600 hospitals 1990-2006 Voluntary reporting of ACS presentation and treatment patterns AMI; >2.5 million patients enrolled Showed 23% reduction in early mortality from AMI over last 16 yr
CRUSADE (Can Rapid Risk Stratification of Unstable Angina Suppress Adverse Outcomes with Early Implementation of ACC-AHA Guidelines) Nationwide, 400 centers 2001-2006 Track adherence to ACC-AHA guidelines for early management of ACS and treatment at discharge ACS (mostly NSTEMI); >200,000 patients 10% decrease in mortality with every 10% increase in guideline adherence
NCDR-ACTION (National Cardiovascular Data Registry–Acute Coronary Treatment and Intervention Outcomes Network) Nationwide; combined CRUSADE and NRMI into one registry 2007-2009 Comprehensive and nationwide assessment of NSTEMI and STEMI care ACS; enrollment ongoing
ACTION Registry-GWTG Nationwide; combined ACTION and GWTG registries 2009-current National registry to assess quality of care and outcomes in ACS patients ACS; enrollment ongoing


Some of the largest national ACS registries in the United States include the NRMI, Can Rapid Risk Stratification of Unstable Angina Patients Suppress Adverse Outcomes with Early Implementation of the ACC and AHA Guidelines (CRUSADE), and Get With The Guidelines (GWTG). In addition to providing a large national databank to collect information on patients with ACS, these registries act as important benchmarking tools to compare performance of various hospitals by reflecting adherence to guideline-recommended therapies.


Several other local and regional registries have played an important role in improving guideline adherence for the management of ACS, including the Cardiac Hospitalization Atherosclerosis Management Program (CHAMP) at the University of California at Los Angeles Medical Center, and the ACC-sponsored pilot project, Guidelines Applied in Practice (GAP). These projects have shown that mere publication of evidence-based guidelines does not guarantee their dissemination, acceptance, or use for patient care. There are many missed opportunities for the treatment of high-risk patients, and treatment disparities persist.


To improve the quality of care of ACS patients further, the NCDR (National Cardiovascular Data Registry)-ACTION was created in 2007 by combining two previously existing national ACS registries, NRMI and CRUSADE. The ACTION (Acute Coronary Treatment and Intervention Outcomes Network) registry is the largest, most comprehensive national ACS database and quality improvement initiative developed in the United States, enabling hospitals to measure their performance in treating patients with ACS against national benchmarks. With more than 150,000 patient records and 350 hospitals participating, the main objective of the ACTION registry is to assess and report treatment patterns and outcomes of STEMI and NSTEMI patients in the United States. ACTION also merged recently with AHA’s GWTG program, which began in 2009 as the ACTION Registry-GWTG.


CHAMP (Cardiac Hospitalization Atherosclerosis Management Program)


The first quality initiative to improve clinical outcomes in patients with acute myocardial infarction was the CHAMP. This was designed and implemented at the University of California Los Angeles (UCLA) Medical Center. CHAMP focused on the initiation of aspirin, statins titrated to achieve a low-density lipoprotein (LDL) cholesterol level less than 100 mg/dL, and beta blocker and angiotensin-converting enzyme (ACE) inhibitor therapy in conjunction with diet and exercise counseling before hospital discharge in patients with established coronary artery disease, including patients with ACS, ischemic heart failure, and those who underwent cardiac procedures (e.g., catheterization, angioplasty and/or stent placement, and coronary bypass). This treatment program was based on the hypothesis that the initiation of therapy in the hospital setting would result in higher utilization rates both at the time of discharge and during longer term follow-up. Implementation of this program involved the use of a focused treatment guideline, standardized admission orders, educational lectures by local innovative thinkers, and tracking and reporting of treatment rates.


The CHAMP initiative achieved a significant increase in the use of lifesaving drugs. Before and after CHAMP, aspirin use in patients at discharge improved from 78% to 92% of patients ( P < .01), beta blocker use improved from 12% to 62% ( P < .01), ACE inhibitor use increased from 4% to 56% ( P < .01), and statin use increased from 6% to 86% ( P < .01; Table 5-2 ) The improvement in drug use was associated with improved clinical outcomes, as reflected in significant reductions in recurrent myocardial infarction and 1-year mortality rates in the post-CHAMP versus pre-CHAMP era (7.8% vs. 3.1%, and 7.0% vs 3.3%, respectively; P < .05 for both comparisons). CHAMP was the first initiative to demonstrate that a systems approach to quality improvement could not only increase the use of guideline-recommended therapies, but also reduce the risk of recurrent events.



TABLE 5–2

Cardiac Hospitalization Atherosclerosis Management Program (CHAMP): Effects of Therapy (%)

















































Therapy Pre-CHAMP Post-CHAMP
At Discharge 1 Yr Postdischarge At Discharge 1 Yr Postdischarge
Aspirin 78 68 92 94
Beta blocker 12 18 61 57
Nitrates 62 42 34 18
Calcium blocker 68 58 12 6
ACE inhibitor 4 16 56 48
Statin 6 10 86 91


GWTG (Get With the Guidelines)


The success of CHAMP subsequently led to a national hospital-based quality improvement AHA initiative known as GWTG. The focus of this program was to ensure treatment compliance in AMI patients before discharge. It was founded on the ACC-AHA guidelines for secondary prevention of cardiovascular diseases, and was designed to help health care providers treat patients consistently in accordance with these accepted guidelines. GWTG enrolled over 600 hospitals, and has a database of >250,000 hospitalized patients with CAD. It uses an Internet-based data management system that facilitates analysis of the care of patients with coronary artery disease (CAD) while they are in hospital, as well as hospital performance with regard to guideline adherence. In addition to collecting data prospectively and measuring performance, the Internet-based patient management tool has incorporated reminder screens to provide immediate reference to the relevant guideline and alerts if measurements or interventions have been omitted.


During the first pilot year of GWTG, the rates of use of aspirin, beta blockers, and ACE inhibitors at discharge remained at 82% to 90% of eligible patients, the use of lipid-lowering therapy at discharge rose from 54% to 78% of patients, and smoking cessation counseling rose from 48% to 81% of patients ( Fig. 5-2 ). Since then, the program has been expanded nationally and has proved to be a sustainable and effective continuous quality improvement program that takes advantage of the teachable moment immediately after an acute event, when the patient is most likely to heed the advice of the health care provider.


Jan 22, 2019 | Posted by in CARDIOLOGY | Comments Off on Acute Coronary Syndrome in North America

Full access? Get Clinical Tree

Get Clinical Tree app for offline access