Chest pain emergency centers: improving acute myocardial infarction care

The Role of Nurses in a Chest Pain Unit

The chest pain unit (CPU) provides a service for patients at moderate-to-low risk for acute coronary syndrome (ACS). Although the number of CPUs has continued to grow worldwide, little has been written on the specific role and contribution of nursing in CPUs. The stay of patients in the CPU can be divided into six stages: triage, diagnosis, treatment, observation/monitoring, discharge, and follow-up. CPU nurses are in a unique position to promote evidence-based practice during all of these stages. Deeper insight into the unique role of nurses in CPUs will promote understanding of what type of knowledge, skills, and attitudes are required to provide the services that will contribute to improved quality of care for chest pain patients.

Achievement of a median door-to-balloon time of less than 90 minutes by implementation of organizational changes in the 'Emergency Department to Cath Lab' pathway: a 5-year analysis

RATIONALE

At present, most patients presenting directly to emergency departments (EDs) do not meet the recommended door-to-balloon goal of less than 90 minutes for ST-elevation myocardial infarction (STEMI) patients. Until the year 2005, the goal of less than 90 minutes door-to-balloon time has been rarely achieved in our hospital (i.e. 17% of all cases).

METHOD

Some organizational changes - including immediate involvement of the cardiologist in ED - were established to improve our performance. To evaluate the results of these changes, we have measured the intervals pain-to-door, door-to-electrocardiogram (ECG) and ECG-to-balloon for all the consecutive STEMI patients (n = 206) observed in our hospital during three sample months (May to July) of the years 2005 to 2009. We have then calculated the times door-to-balloon and pain-to-balloon (total ischemic time).

RESULTS

We have demonstrated that the door-to-balloon time has been progressively reduced to less than 90 minutes in 73% of patients. Only 4.5% of all patients still have a door-to-balloon time greater than 150 minutes (17% in 2005). It is also notable the 60% reduction (from 330 to 140 minutes) of the pain-to-door time, the so-called 'out of hospital avoidable delay', was achieved by a sensitization campaign directed to the whole population of the province.

CONCLUSION

Taken together, all these organizational changes have allowed to reduce the total ischemic time from 465 minutes in year 2005 to 232 minutes in year 2009, thereby demonstrating the effectiveness of our intervention.

Assessing risk in acute chest pain: The value of stress myocardial perfusion imaging in patients admitted through the emergency department

BACKGROUND

To prospectively assess the clinical value of stress-gated myocardial single photon emission computed tomography (SPECT) for triaging patients admitted through the emergency department (ED) with acute chest pain (ACP).

METHODS

Prospective, observational cohort study in 1,576 consecutive patients who were evaluated for ACP over a 29-month period. Stress SPECT was performed within 24 hours of admission from the ED. Analysis included quantification of total and ischemic left ventricular perfusion defect size (PDS). Cardiac events were defined as an acute coronary syndrome during the index hospitalization or in follow-up over 7.3 ± 2.8 months.

RESULTS

Eighty-five cardiac events occurred in 77 patients (4.9%). SPECT was abnormal in 135 patients (8.6%) of whom 83 (61.5%) had a reversible defect. Event rates were significantly higher in patients with an abnormal (40%) versus a normal (1.6%) SPECT (P < .0001); and in those with a (1) large (>15%) versus small (≤15%) PDS (50.0% vs 33.7%, P = .05) and (2) large (>10%) versus small (≤10%) ischemic PDS (87.5% vs 42.4%, P < .0001, respectively). SPECT best predicted cardiac events by multivariate analysis. The addition of SPECT to clinical variables significantly improved overall risk prediction (global χ(2) 103.6 vs 207.1, P < .001).

CONCLUSIONS

Stress SPECT can accurately assess risk in a heterogeneous group of patients with ACP of unclear cardiac etiology, and beyond that provided by a clinical risk assessment alone. Our results support the use of stress SPECT for identifying very low-risk ACP patients with normal study results who can be safely discharged home.

Plasma myeloperoxidase concentration predicts the presence and severity of coronary disease in patients with chest pain and negative troponin-T

BACKGROUND

A non-negligible proportion of patients with chest pain with negative cardiac troponin may harbor a disrupted coronary plaque. A marker of plaque rupture upstream from myocardial necrosis may help identify high-risk patients among this patient population. The purpose of this study was to investigate the correlation of plasma myeloperoxidase (MPO) concentration and angiographic coronary disease among patients with suspected troponin-negative coronary syndromes.

PATIENTS AND METHODS

Patients presenting with chest pain and negative cardiac troponin-T concentration and undergoing coronary angiography were enrolled in our study. Plasma MPO concentration was measured using a single blood sample collected prior to cardiac catheterization. The primary angiographic endpoint was the presence of at least one coronary stenosis causing a 70% or more diameter reduction; secondary endpoints were number of diseased vessels, presence of coronary thrombus, and lesion ulceration. The main clinical endpoint was coronary revascularization.

RESULTS

Three hundred and eighty-nine patients were enrolled. Presence of coronary stenosis causing a 70% or more diameter reduction increased with increasing quartiles of myeloperoxidase concentration (P<0.0001), as did the presence of coronary thrombus (P<0.0001) and plaque ulceration (P<0.0001). The need for percutaneous coronary revascularization also increased with increasing quartiles of systemic myeloperoxidase levels (P<0.0001). Coronary surgical revascularization did not differ among myeloperoxidase quartiles.

CONCLUSION

Among patients with chest pain without troponin elevation, a single measurement of plasma MPO concentration can help identify patients with a higher risk of having significant coronary stenoses and high-risk angiographic features.

The evolution of chest pain pathways

Patients presenting to the emergency department with chest pain require prompt identification and referral, as early treatment of patients with an acute coronary syndrome (ACS) is crucial to decrease morbidity and mortality (Steurer et al, Emerg Med J. 2010;27:896-902). Although rule-in ACS is critical and time dependant, other difficulties arise during the rule-out ACS process (Steurer et al, Emerg Med J. 2010;27:896-902). Inappropriate discharge of patients with misdiagnosed acute myocardial infarction is associated with significant morbidity and mortality. Concerns relating to inappropriate discharge result in readmission with resultant lengthy hospital stays, high costs, and contribute to overcrowding and bed block (Amsterdam et al, J Am Coll Cardiol. 2002;40:251-256; Cardiol Clin. 2005;23:503-516; Furtado et al, Emerg Med. In press; Karlson, Am J Cardiol. 1991;68:171-175; Ng et al, Am J Cardiol. 2001;88:611-617; Ramakrishna et al, Mayo Clin Proc. 2005;80:322-329; Stowers, Crit Pathw Cardiol. 2003;2:88-94). The challenge of chest pain diagnosis has led to a number of associated problems within the health care system. The growing need for improvements in consistency of patient care, resource efficiency, and quality of patient healthcare has led to the development of chest pain pathways (Erhardt et al, Eur Heart J. 2002;23:1153-1176). The development and implementation of chest pain pathways is not without difficulties. These may arise from differences in the management approaches of health practitioners, poor adherence to guidelines, and concerns for costs. New procedures such as new cardiac injury markers, stress testing, and specialized chest pain units have led to a reduction in admission rates and length of stay, reduced costs, and a reduction of inappropriate discharge of patients with ischemic heart disease.

Does coronary artery calcium scoring add to the predictive value of coronary computed tomography angiography for adverse cardiovascular events in low-risk chest pain patients?

OBJECTIVES

Coronary angiography calcium score (CACS) is included for patients who receive coronary computed tomography angiography (CTA) as part of diagnostic testing for low-risk chest pain. Both tests add radiation exposure, and it is unclear whether the combination provides more information than either test alone. The objective was to asses if CACS = 0 determines freedom from coronary artery disease (CAD) and whether the addition of CACS to coronary CT angiography provides additional risk stratification information or helps predict 30-day cardiovascular outcomes.

METHODS

This was a secondary analysis of a prospective cohort study at an urban university hospital emergency department (ED), of patients with symptoms suggestive of potential acute coronary syndrome (ACS) and low Thrombolysis in Myocardial Infarction (TIMI) risk scores who received coronary CTA. Data collected included demographics and medical history. The main outcome was CAD, defined as the presence of a maximal stenosis >50% on coronary CTA, stratified by CACS results. The secondary outcome was cardiovascular events including death, myocardial infarction, or revascularization at 30 days. Data were analyzed with standard descriptive techniques and relative risks (RR) with 95% confidence intervals (CIs).

RESULTS

A total of 1,049 patients were enrolled (median age = 48.1 years; interquartile range [IQR] = 42.4 to 53.3 years); 55% were female, and 63% were black or African American. Of these, 17 of 795 (2.1%) with CACS of 0 had CAD, 16 of 169 patients (9.5%) with CACS of 0.1 to 99 had CAD, 53.3% (32 of 60) with CACS between 100 and 399 had CAD, and 10 of 23 (43.5%) with CACS ≥ 400 had CAD. There was a higher likelihood of significant CAD with increased CACS. Patients who had a calcium score of 0 but still had CAD were more likely to be young (50 years old or less; RR = 1.73, 95% CI = 1.01 to 2.96). For the secondary outcome, there were 15 cardiovascular events within 30 days: one patient with CACS = 0 and no CAD (1 of 733; 0.1%), one patient with CACS > 0 and no CAD (1 of 182; 0.5%), four patients with CACS = 0 and CAD (4 of 17; 23.5%), and nine patients with CACS > 0 and CAD (9 of 58; 15.5%), with a net reclassification index of -0.001 (p = 0.32).

CONCLUSIONS

In the study sample, elevated CACS was associated with a higher likelihood of underlying CAD on coronary CTA, but the addition of CACS to coronary CTA did not help predict 30-day cardiovascular events.

Design of a comprehensive chest pain initiative in an academic urban hospital

We describe the development and institution of an initiative based on a clinical diagnostic algorithm and treatment pathways, facilitated by cardiac nurse practitioners, for the treatment of the diverse group of patients with chest pain who seek treatment at our urban-based institution. We believe that our chest pain initiative incorporates previous strategies of rapid emergency department management with inpatient-based care while providing a framework for outpatient follow-up and secondary prevention. These strategies allow our hospital to meet its goals of providing chest pain patients with standardized, high-quality, and expeditious care, given the challenges faced by an academic urban hospital.

2007 update to the ACC/AHA guidelines for the management of patients with unstable angina and non-ST-segment elevation myocardial infarction: implications for emergency department practice

The American College of Cardiology and American Heart Association have updated their guidelines for the management of non-ST-segment-elevation acute coronary syndrome for the first time since 2002. In the interim, several important studies affecting choices of therapy potentially begun in the emergency department have been completed, and care patterns have changed and matured significantly. In this review, we present the new recommendations that are pertinent to emergency medicine practice and comment on their potential implementation into an evidence-based, multidisciplinary approach to the evaluation and management of this challenging patient population.

Positive impact of an interdisciplinary chest pain initiative on traditionally underserved populations

BACKGROUND

We assessed the clinical impact of an interdisciplinary, cardiac nurse practitioner-facilitated chest pain (CP) initiative that stresses an early invasive approach for patients with CP with acute coronary syndromes in traditionally underserved patient populations, including females, blacks, Hispanics, and patients older than 60 years.

METHODS

Two groups of patients were identified: Pre-CP initiative (December 1999-February 2000) and post-CP initiative (December 2000-February 2001).

RESULTS

Analysis of 714 patients revealed significantly more cardiac diagnoses post-CP initiative (61% pre-CP initiative vs. 73% post-CP initiative, P = 0.002), including in patients with myocardial infarction (MI) who were older than 60 years, females, and Hispanics. There was a significant increase in rates of cardiac catheterizations within 1 week of admission (10.5% vs. 20.4%, P <0.001), including in Hispanics. For rates of coronary artery stenting and/or bypass grafting (CABG), there was also a significant increase post-CP initiative (2.5% vs. 10.1%, P = 0.0005), as well as for Hispanics. Length of stay was significantly reduced for patients older than 60 years (8.3 vs. 5.8 days, P = 0.002).

CONCLUSION

Establishment of an interdisciplinary, cardiac nurse practitioner-facilitated CP initiative is associated with improvement in several clinical processes and outcomes: increased cardiac disease diagnosis in females, Hispanics, and patients older than 60 years; increased rates of cardiac catheterizations in Hispanic patients, increased rates of coronary artery stenting and/or CABG, particularly in Hispanic patients; and decreased length of stay in patients older than 60 years. These data support a targeted interdisciplinary CP initiative as a strategy to systematically enhance access to cardiovascular diagnosis in underserved patient populations.

Planar myocardial perfusion imaging for evaluation of patients with acute chest pain

BACKGROUND

Rest single-photon emission computed tomographic (SPECT) perfusion imaging identifies acute myocardial ischemia in patients with chest pain in the emergency department; however, the costs are high and radioisotopic services are usually not available 24 h a day. Planar imaging through a portable gamma camera may be useful in this setting. However, planar imaging might be associated with less predictive values in comparison with a gated SPECT imaging. We sought to evaluate rest planar myocardial perfusion imaging for evaluation and triage of patients with suspected acute cardiac ischemia.

METHODS

Patients within 6 h of chest pain onset and nondiagnostic electrocardiograms (ECGs) underwent planar myocardial perfusion imaging. Studies showing perfusion defects were considered suggestive of acute coronary syndromes. The results of planar scintigraphy were compared with the clinical diagnosis and outcomes. All patients were followed up and monitored for the occurrence of major cardiac events 120 days after hospital discharge.

RESULTS

71 patients underwent scintigraphy. Twenty-one (30%) patients had acute coronary syndromes, 15 (21%) had major cardiac events (8 had myocardial infarction and 7 underwent myocardial revascularization). Planar scintigraphy demonstrated perfusion defects in 21 patients, 16 (76%) patients with acute coronary syndromes, 12 (80%) patients who had major cardiac events and in 7 (88%) patients with myocardial infarction. The negative predictive value of planar scintigraphy was 90% for diagnosis of acute coronary syndromes and 94% for detecting major cardiac events.

CONCLUSION

Early planar myocardial perfusion imaging allowed rapid and accurate risk stratification of emergency departments patients with possible myocardial ischemia and nondiagnostic ECGs.

The Erlanger chest pain evaluation protocol: a one-year experience with serial 12-lead ECG monitoring, two-hour delta serum marker measurements, and selective nuclear stress testing to identify and exclude acute coronary syndromes

STUDY OBJECTIVE

We determine the overall use of a 6-step accelerated chest pain protocol to identify and exclude acute coronary syndrome (ACS) and to confirm previous findings of the use of serial 12-lead ECG monitoring (SECG) in conjunction with 2-hour delta serum marker measurements to identify and exclude acute myocardial infarction (AMI).

METHODS

A prospective observational study was conducted over a 1-year period from January 1, 1999, through December 31, 1999, in 2,074 consecutive patients with chest pain who underwent our accelerated evaluation protocol, which includes 2-hour delta serum marker determinations in conjunction with automated SECG for the early identification and exclusion of AMI and selective nuclear stress testing for identification and exclusion of ACS. In patients not undergoing emergency reperfusion therapy, physician judgment was used to determine patient disposition at the completion of the 2-hour evaluation period: admit for ACS, discharge or admit for non-ACS condition, or immediate emergency department nuclear stress scan for possible ACS. A positive protocol was defined as a positive result in 1 or more of the 6 incremental steps in our chest pain evaluation protocol: (1) initial ECG diagnostic of acute injury or reciprocal injury; (2) baseline creatine kinase (CK)-MB level of 10 ng/mL or greater and index of 5% or greater or cardiac troponin I level of 2 ng/mL or greater; (3) new/evolving injury or new/evolving ischemia on SECG; (4) increase in CK-MB level of +1.5 ng/mL or greater or cardiac troponin I level of +0.2 ng/mL or greater in 2 hours; (5) clinical diagnosis of ACS despite a negative 2-hour evaluation; and (6) reversible perfusion defect on stress scan compared with on resting scan. All patients were followed up for 30-day ACS, which was defined as myocardial infarction (MI), percutaneous coronary intervention/coronary artery bypass grafting, coronary arteriography revealing stenosis of major coronary artery of 70% or greater not amenable to percutaneous coronary intervention/coronary artery bypass grafting, life-threatening complication, or cardiac death within 30 days of ED presentation.

RESULTS

Discharge diagnosis in the 2,074 study patients consisted of 179 (8.6%) patients with AMI, 26 (1.3%) patients with recent AMI (decreasing curve of CK-MB), and 327 (15.8%) patients with 30-day ACS. At 2 hours, sensitivity and specificity for MI (AMI or recent AMI) of SECG plus delta serum marker measurements was 93.2% and 93.9%, respectively (positive likelihood ratio 15.3; negative likelihood ratio 0.07). At the completion of the full ED evaluation protocol (positive result in >or=1 of the 6 incremental steps), sensitivity and specificity for 30-day ACS was 99.1% and 87.4%, respectively (positive likelihood ratio 7.9; negative likelihood ratio 0.01).

CONCLUSION

An accelerated chest pain evaluation strategy consisting of SECG, 2-hour delta serum marker measurements, and selective nuclear stress testing in conjunction with physician judgment identifies and excludes MI and 30-day ACS during the initial evaluation of patients with chest pain.

Acute myocardial infarction 2000 recognition

Acute myocardial infarction occurs in two forms: unheralded attacks and those preceded by unstable angina. As the leading cause of death in the US, accounting for over 95 billion dollar annual cost, acute myocardial infarction requires up-to-date recognition and management.

Combination of Goldman risk and initial cardiac troponin I for emergency department chest pain patient risk stratification

BACKGROUND

Accurate identification of low-risk emergency department (ED) chest pain patients who may be safe for discharge has not been well defined. Goldman criteria have reliably risk-stratified patients but have not identified any subset safe for ED release. Cardiac troponin I (cTnI) values have also been shown to risk-stratify patients but have not identified a subset safe for ED release.

OBJECTIVE

To test the hypothesis that ED chest pain patients with a Goldman risk of < or =4% and a single negative cTnI (< or =0.3 ng/mL) at the time of ED presentation would be safe for discharge [<1% risk for death, acute myocardial infarction (AMI), revascularization].

METHODS

A prospective cohort study was performed in which consecutive ED chest pain patients were enrolled from July 1999 to November 2000. Data collected included patient demographics, medical and cardiac history, electrocardiogram, and creatine kinase-MB and cTnI. Goldman risk stratification score was calculated while patients were still in the ED. Hospital course was followed daily. Telephone follow-up occurred at 30 days. The main outcome was death, AMI, or revascularization (percutaneous transluminal coronary angioplasty/stents/coronary artery bypass grafting) within 30 days.

RESULTS

Of 2,322 patients evaluated, 998 had both a Goldman risk < or =4% and a cTnI < or =0.3 ng/mL. During the initial hospitalization, 37 patients met the composite endpoint (3.7%): 6 deaths (0.7%), 17 AMIs (1.7%), 18 revascularizations (1.8%). Between the time of hospital discharge and 30-day follow-up, 15 patients met the composite endpoint: 4 deaths (0.4%), 6 AMIs (0.6%), and 5 revascularizations (0.5%). Overall, 49 patients met the composite endpoint (4.9%; 95% CI = 3.6% to 6.2%): 10 deaths (1.0%; 95% CI = 0.4% to 1.6%); 23 AMIs (2.3%; 95% CI = 1.4% to 3.2%), and 23 revascularizations (2.3%; 95% CI = 1.4% to 3.2%) within 30 days of presentation.

CONCLUSIONS

The combination of two risk stratification modalities for ED chest pain patients (Goldman risk < or =4% and cTnI < or =0.3 ng/mL) did not identify a subgroup of chest pain patients at <1% risk for death, AMI, or revascularization within 30 days.

Provocative testing for chest pain

Since the first Chest Pain Center (CPC) was set up in 1981 to speed up the evaluation and treatment of patients with acute myocardial infarction, the original concept has been expanded to include rapid evaluation of chest pain patients with the appropriate streamlining of care and incorporation of the latest in technology. It has also been established that among patients presenting with acute chest pain, a very low-risk group with less than 5% probability of a coronary event can be identified. The recognition of this group could prevent unnecessary admissions, affording more appropriate patient care and improved cost-effectiveness. The efficient management of these chest pain patients requires that there be reductions in: (1) delays in therapy, (2) "soft" admissions, (3) inappropriate dispositions, and (4) cost. With time, provocative testing (PT) for chest pain patients has been brought forward to the frontline. PT methods are now being studied in hundreds of emergency department (ED) patients, followed up over several months to ascertain the predictive value of both positive and negative test results. More and more CPCs are now using PT as part of their management protocol, in terms of decision-making pertaining to prognostification, treatment and disposition. This could be in the form of the ECG graded exercise test (GXT), stress echocardiography (SE) and stress single-photon emission computed tomography (SPECT) radionuclide perfusion imaging. The GXT is fairly widely used currently, SE is gaining popularity and stress radionuclide perfusion imaging will perhaps gain more acceptance as the experience with its use as well as the number of randomized controlled studies increase. As we move into the new millennium, the emergency physicians must familiarize themselves with the latest in the state-of-the-art concepts and technology to render improved, up-to-date and more cost-effective patient care.