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* From the Center for Pulmonary and Critical Care Medicine, North Shore University Hospital, Manhasset, NY.
Correspondence to: Alan M. Fein, MD, FCCP, North Shore University Hospital, 300 Community Dr, Manhasset, NY 11030; e-mail: afein{at}nshs.edu
| Abstract |
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Objective: To identify a subset of patients in whom telemetry monitoring does not alter management.
Design: Prospective observational study.
Setting: Large tertiary care facility.
Patients: A total of 414 patients consecutively admitted from the emergency department for suspected acute coronary syndromes were studied. Patients were excluded if they presented with ST-segment elevations, were revascularized on hospital admission, were admitted to a surgical service, were transferred from another floor or unit, or remained in the emergency department for the course of the stay.
Outcomes: Events were defined as development of myocardial infarction, episodes of chest pain, new or rapid atrial arrhythmias, ventricular arrhythmias, any form of AV nodal block, and asystole. Intervention or change in management was any increase, decrease, or change in medication, cardioversion, electrophysiology study, or transfer to the ICU.
Results: Patients who had atypical chest pain and normal ECG findings were significantly less likely to have both intervention and events (4 interventions vs 23 interventions [p < 0.0001], 12 events vs 45 events [p < 0.0001]), compared to those with typical chest pain and abnormal ECG findings. When normal laboratory values were added, only four telemetry events were observed.
Conclusion: Patients with atypical chest pain and normal ECG findings represent a subset of patients with low risk for life-threatening arrhythmia. Use of telemetry monitoring in this subset of patients should be reevaluated.
Key Words: angina arrhythmia chest pain monitoring telemetry triage
| Introduction |
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Recently, it was found to be more cost-effective,5 as well as medically appropriate,6 7 8 to place a patient with low risk of AMI in a non-ICU monitored setting. This has led to a larger proportion of chest pain admissions to these non-ICU telemetry beds and a significant expansion of this capability. In fact, our hospital has increased the number of these beds twofold over the past year.
The decision by physicians to admit their patients to this unit is often guided by previously published guidelines by the American College of Cardiology in 1991.9 According to these guidelines, a patient suspected of having an AMI should be monitored until infarction can be excluded. However, Estrada et al10 11 reported that telemetry identified an arrhythmia that resulted in a transfer to the ICU in only 0.8% of all admissions. This low incidence of significant events for all patients admitted for chest pain prompted us to conduct a prospective observational study to evaluate characteristics of low-risk patients with an uneventful telemetry stay. We evaluated both cardiac events and medical interventions.
The purpose of our study was to identify a subset of patients in whom telemetry monitoring does not alter management. Accordingly, this expensive and limited resource could be allocated more efficiently.
| Materials and Methods |
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Heart rate and rhythm are transmitted continuously by two leads (aVL and V1) fashion. Technicians trained to recognize rhythm disturbances continuously monitor the cardiac rhythm, and report to the nursing and medical staff.
Patient Populations
This study was prospective and observational and conducted over 3 months. Four hundred fourteen patients consecutively admitted from the emergency department to telemetry for suspected acute coronary syndromes were studied. Patients were excluded if they presented with ST-segment elevations, were revascularized on admission, were admitted to a surgical service, were transferred from another floor or unit, or remained in the emergency department for the course of the stay.
One of the investigators obtained clinical information, including previous history (coronary artery disease, congestive heart failure, or arrhythmia), and cardiac risk factors (hypertension, diabetes mellitus, hypercholesterolemia, or family history or smoking history) from the medical records of the study patients. This information was obtained concurrently at admission and recorded on data sheets for standardization and further analysis.
Chest pain, including rest pain, was further classified as typical or atypical based on previously published criteria.7 Typical chest pain was defined as pressure-like retrosternal pain being exacerbated by exercise and relieved at rest or with administration of nitroglycerin. Additionally, if the pain radiated to the neck or left shoulder or arm, it was classified as typical. Atypical chest pain was defined as pain reproducible by palpation, radiating to the back, abdomen, or legs, or was "stabbing" in nature. Chest pain associated with symptoms of palpitations, shortness of breath, and syncope on hospital admission was also noted.
ECGs, electrolytes, cardiac enzymes, and chest radiographs were recorded12 and interpreted by the patients attending physicians. Patients with infarction or injury pattern defined as significant Q waves or ST-segment elevations were excluded from our study. Ischemia was defined as any horizontal or downsloping ST-segment depression > 0.1 millivolts (0.2 millivolts in leads V1 through V3) measured 80 ms from the J point, or inverted T waves > 0.3 millivolts. Upsloping ST-segment depressions were included if they were > 2 mm or were dynamic in nature. Atrial arrhythmia was considered any supranodal rhythm other than sinus. Conduction abnormality was considered a right or left bundle-branch block and/or any degree of AV block. Sinus bradycardia (heart rate < 60 beats/min) and sinus tachycardia (heart rate > 100 beats/min) were also recorded.
Outcomes
Events were defined as the development of myocardial infarction (MI), episodes of chest pain, new or rapid atrial arrhythmias, ventricular arrhythmias including nonsustained or sustained ventricular arrhythmia, any form of AV nodal block, and asystole. MI was defined by elevated creatinine kinase (CK) levels (> 200 U), with total myocardial bands (> 10 U) or percentage of myocardial bands > 5%. An intervention or change in management was defined as any increase, decrease, or change in medication, cardioversion, electrophysiology study, or transfer to the ICU.
Statistics
Data were collected by the investigators and analyzed with the North Shore University Hospital biostatistics department. Using software (Filemaker Pro; Filemaker; Santa Clara, CA), a database was created. Data were then analyzed using Microsoft Excel (Microsoft; Redmond, WA) and SAS (SAS Institute; Cary, NC). Most of the results are expressed as percentages, and
2 or the Fisher exact test (as appropriate) were used to compare percentages between different groups of patients. Statistical results were considered significant if the two-tailed p value was < 0.05.
| Results |
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Hypertension was the most common risk factor for coronary artery disease (n = 225, 54%). About one fourth of patients had a history of hypercholesterolemia (n = 118). Diabetes mellitus was a risk factor in 89 patients, smoking was a risk factor in 86 patients, and a family history significant for coronary artery disease was a risk factor in 36 patients.
Presentation
The majority of patients presented with atypical chest pain (n = 248, 60.%; Table 2
). One hundred sixty-six patients presented with typical chest pain (40%). There were no associated symptoms of dyspnea, palpitations, or syncope in most patients (n = 254, 61%), with the remaining 160 patients (39%) having one or more of these symptoms. Specifically, 106 patients presented with associated dyspnea, 63 patients presented with associated palpitations, and 19 patients presented with syncope. Two hundred sixty-five patients (64%) had one or more laboratory abnormalities, including WBC count elevation (n = 81), electrolyte abnormalities (n = 46), elevated CK levels (n = 54), and congestive heart failure by chest radiograph (n = 31).
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Outcomes
After hospital admission, 107 patients (28.5%) had one or more events while on telemetry (Tables 3
, 4
). The majority of these were atrial arrhythmias or ectopy (n = 46, 11%) and ventricular arrhythmias or ectopy (n = 45, 11%). Sinus bradycardia or tachycardia was noted in 36 patients. Additionally, among 12 different patients, there were three deaths, 6 patients with episodes of asystole, and 3 patients with complete heart block.
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Of the 248 patients (Fig 1 ) who presented with atypical chest pain, 47 patients (19%) had events, compared to 60 patients of the 166 patients (36%) presenting with typical chest pain (p < 0.0001). Among those patients with events, 40% of patients (19 of 47 patients) with atypical chest pain had a change in management, compared to 47% of those with typical chest pain (28 of 60 patients; p < 0.005). Of the patients with typical chest pain, 22 patients had an MI, compared to only 6 patients with atypical chest pain. Patients with atypical chest pain and events had a lower rate of intervention.
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Normal ECG findings also correlated well with an uneventful hospital course. With normal ECG findings (Fig 2 ), 27 patients (13%) had an event, compared to almost 39% of patients with abnormal admission ECG findings (p < 0.0001). Interventions were also more uncommon in patients with normal ECG findings on presentation (9 patients vs 38 patients, p < 0.0001). Among patients with abnormal admission ECG findings, there were 21 MIs, compared to 7 MIs in the group with normal ECG findings.
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| Discussion |
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CCUs were introduced in the United States in the early 1960s in an attempt to lower the high mortality rate among hospitalized patients with AMI.2 Since then, it has been the standard of care in the United States to admit all patients with suspected MI into CCUs equipped to respond to life-threatening arrhythmias. Ninety percent of patients with AMI have cardiac rhythm abnormality, and 25% have a conduction disturbance. In addition, the incidence of serious arrhythmias, such as ventricular fibrillation, is greatest within the first hour of AMI.4 However, most patients admitted to the CCU with suspected AMI do not, in fact, prove to have this diagnosis.5 In contrast to this approach, a chest pain observational unit has been developed. Units like this have already been adopted by many hospitals in the United States. These institutions provide extended care in the emergency department to avoid admission of patients with low risk of acute coronary syndrome.
This led to cost-effective analyses5 and predictive instruments6 7 8 to identify low-risk patients who may be initially admitted to an intermediate care unit.13 14 15 Analysis examining the clinical and economic consequences of alternatives to CCU care have demonstrated that patients at low risk of AMI can be managed in an intermediate care unit, with telemetry monitoring.3 Studies16 17 18 19 have supported the safety and efficacy of telemetry monitoring in those patients with suspected AMI who have "ruled in."
The value of telemetry monitoring in the non-CCU setting for low-risk acute coronary syndromes has been questioned. Estrada et al10 observed 2,240 patients admitted to telemetry for various indications, including chest pain, syncope, congestive heart failure, and arrhythmias, and noted that the role of telemetry monitoring may be overestimated by physicians. These authors reported that telemetry monitoring rarely led to management changes and cardiologists perceived telemetry as a useful adjunct to care in only 12.6% of cases. In addition, < 1% of all patients admitted to telemetry had arrhythmias detected by telemetry that led to a transfer to a CCU.10
If a subset of patients in whom telemetry monitoring would not alter management could be identified on presentation to the emergency department, it may be possible to allocate available telemetry monitoring more efficiently. Clinical practice guidelines10 published in 1994 recommend that patients with unstable angina who present to the emergency department judged to be at high risk be admitted to the CCU. Those at intermediate risk can be admitted to telemetry units, and those at low risk can be further evaluated and even managed as outpatients.20 However, studies21 22 have described the outcome of missed MIs in patients sent home from the emergency department. Physicians are therefore reluctant to send patients home who present with low-risk suspected acute coronary syndromes. One hundred one patients (25%) of the total presenting with atypical chest pain, no associated symptoms, normal ECG findings, and normal laboratory values were admitted to telemetry in our study (Fig 3) . Of these, no patients had MI by serial cardiac enzymes. Of the four patients who had arrhythmias (sinus bradycardias and tachycardias), there were no interventions. These low-risk patients, according to the 1994 guidelines and based on our results, could have been managed as outpatients. Patients with atypical chest pain and normal ECG findings (153 of 414 patients, 37%) appear to be the group that warrants hospital admission but does not gain benefit from telemetry monitoring. In this group, there were 3 of 153 patients (2%) who ruled-in by serial cardiac enzymes, which would have been missed if these patients were not admitted to the hospital. It should be noted that telemetry monitoring neither led to the diagnosis nor revealed events necessitating intervention in this subset of patients.
It is perceived that telemetry provides a higher level of care than can be provided on a general ward. However, this level of care is maintained by an increased cost of nursing, telemetry technicians, and equipment. Thus, unnecessary admissions to telemetry translate into unnecessary added costs.
A major limitation of this study is that it is an observational study. Furthermore, the study is limited by the small sample size (153 patients with atypical chest pain and normal ECG findings).
Additionally our findings do not apply to other indications for telemetry, including patients admitted through the emergency department for evaluation of syncope, new-onset arrhythmia, coronary artery disease awaiting revascularization, or those transferred from the catheterization laboratory, general medical floor, or ICU.
Although an ICU/CCU or telemetry unit is likely to provide better treatment for most patients, these beds represent a limited resource. Patients with atypical chest pain and normal ECG findings are a subset of patients in whom telemetry monitoring does not generally affect hospital course. Previous hospital admission guidelines suggested that these patients could be managed as outpatients. In fact, some of these patients do indeed prove to have MI. Thus, admission to the hospital and serial cardiac enzymes is warranted, even if telemetry is not.
| Conclusion |
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| Footnotes |
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Received for publication January 26, 2001. Accepted for publication January 4, 2002.
| References |
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