Ever since its inception, electrocardiographic monitoring, also known as telemetric or cardiac monitoring, has revolutionised the medical care of the hospitalised patient and remains an invaluable tool both for monitoring and treatment. However, significant overuse does occur; this can be both wasteful of healthcare funds and even dangerous to the patients. The goal of clinicans should be to understand how and when cardiac monitoring is best implemented. Only by so doing can maximum utility be achieved as well as its ability to assist patient care.
by Dr PP Monteleone and Dr WJ Brady
Origins and current use
Amazingly, the man often referred to as “the father of the electrocardiogram,” Dr Willem Einthoven, first transmitted electrocardiographic information via telephone lines in 1906 from his physiology laboratory in Leiden, The Netherlands to his clinic at the Academic Hospital nearly a mile away [1]. This transmission of electrocardiography was developed because Einthoven’s original string galvanometer weighed nearly 300 Kg, used heavy buckets of saline to serve as electrodes and required five people to operate it. Thus, the predecessor of modern telemetry, “Le Telecardiogramme” was initially developed to bring the machine’s function to the patients when the reverse, that is, bringing the machine to the patients, would be simply impractical [2]
As the modern era of medicine has progressed, such practical limitations have eroded somewhat. Classic electrocardiographic monitoring (ECGM) provides the ability to continuously monitor patients admitted to hospitals for dysrhythmia. Because of the speed with which acute dysrhythmia can be fatal, the ability to recognise it immediately is invaluable. Practitioners thus use ECGM in patients admitted with conditions predisposing to dysrhythmia, ranging from various cardiovascular ailments to neurologic, respiratory, traumatic, metabolic and toxicologic syndromes. Fifty years ago ECGM demanded intensive care unit (ICU) admission. Modern hospitals have however now developed intermediate-level telemetry wards to provide for monitoring of patients at lower risk of dysrhythmia while avoiding the prohibitive cost of ICU care [3]. However regardless of the unit to which they are admitted, the degree of clinical risk among patients placed on ECGM often varies from significant to negligible. The corresponding utility of ECGM thus ranges from lifesaving to none.
Outcomes of ECGM
Detailed evaluation of the precise utility of ECGM is understandably limited in that it would be both unethical and impossible to randomise admitted patients for the purposes of evaluating and comparing health outcomes in monitored and unmonitored patients. However there is a great deal of observational research demonstrating the limitations of ECGM.
Much of this work is aimed at determining the pre-test probability of the use of ECGM, i.e. developing criteria by which the “risk” for dysrhythmia can be defined and then asking if ECGM improves health outcomes in patients at that level of risk. Some work has used a primary outcome measurement of “alteration of clinical care” to assess the necessity of ECGM. A prospective cohort analysis by Hollander et al. followed 460 patients admitted from an ER to ECGM unit [4]. In only one of these patients (who was post-operative from an aortic dissection tear) were ECGM-derived clinical data used to alter the hospital course or have treaments carried out. Similar work from Saleem et al. and Snider et al. gave the same findings, namely that the care of patients who were deemed to be low risk for dysrhythmia was not influenced by ECGM. [5, 6].
Mortality as an outcome was assessed by Schull et al. with equally interesting, and possibly more disturbing, results [7]. All 8,932 patients placed on ECGM when admitted to a Toronto tertiary care hospital over a five year period ending in 2000 were retrospectively assessed. Of the monitored patients, 20 were found to have suffered cardiac arrest during their inpatient stay. Only 56% of the cardiac arrests in “ECGM monitored” patients were actually recognised as a result of abnormal signalling by the monitor. Three of the total of arresting patients survived to discharge; two of these had monitor-signalled events. In short, among all 8,932 patients, about 1 in 5,000 were survivors of monitor-signalled cardiac arrests [7]. This suggests that there is very little mortality benefit to be derived from the routine use of ECGM.
Dangers of the overuse of ECGM
Furthermore, we must remember that ECGM is not a harmless intervention. The decision to triage to ECGM admission is a contributor to the phenomenon of overcrowding in both emergency room and telemetry-capable units. During the course of a study conducted by Durairaj et al., an average of three patients a day were denied admission to the cardiac monitoring ward due to a lack of beds while an average of four of the 12 telemetry beds were occupied by very low-risk patients [8]. Overcrowding is a clear threat to patient health outcomes. Overstressed units provide poorer care and overcrowded tertiary care facilities limit hospital transfer of patients in dire need of tertiary care.
Misuse of telemetry also has a significant negative financial impact on a medical facility and on patients. Bayley et al. conducted a prospective cohort study of 817 chest pain patients over the age of 24 years who were admitted from the ED to a monitored bed [9]. The study focused on the extra cost to the hospital of a lengthened ED stay for patients waiting to be admitted on ECGM. The annual cost in lost hospital revenue for chest pain patients waiting for an ECGM bed was determined to be $168,300 or about $204 for every patient who waited longer than three hours for a hospital bed. The study probably even underestimated the true cost of lengthened ED stays in that the analysis did not consider lost revenue from patients who left without being seen, ambulance diversions to other EDs, and other
intangible factors.
Recommendations for risk stratification and patient selection
No one should ever doubt the utility of Einthoven’s creation. The advent of ECGM allows modern physicians to constantly monitor the electrocardiography of patients at risk for dysrhythmia, both to improve their clinical treatment and to prevent their sudden cardiac death. What is therefore most important is to focus on improving the utility of the implementation of ECGM. The best first step towards this end is stratification of risk for dysrhythmia as a means of selecting patients for ECGM admission.
In 1991, the American College of Cardiology (ACC) together with the Emergency Cardiac Care Committee (ECC) issued a joint position statement to address which patients were appropriate for ECGM admission [10]. It described ECGM indication as Class I (cardiac monitoring is indicated in most if not all such patients), Class II (cardiac monitoring may be of benefit in some patients but is not considered essential for all) and Class III (cardiac monitoring is not indicated because a patient’s risk of a serious event is so low that monitoring has no therapeutic benefit). This same classification system was used in the 2004 AHA revision to the guidelines which assigned a class of indication for use of ECGM to most presenting conditions that commonly result in ECGM admission [11]. In addition to making recommendations regarding when to monitor for dysrhythmia, the position statement also made recommendations on when to use
modern ECGM applications to monitor for dynamic ischaemia and QT prolongation [Table I].
Despite much observational research assessing the utility of ECGM, no experimental evidence exists that suggests how and when to best implement ECGM. Furthermore, ethical and study design limitations are likely to prevent such experimental evidence from ever being developed. In the absence of such randomised clinical trial-derived guidelines, the 2004 statement thus sought to provide in a consensus expert opinion the best available type of assistance to meet the questions and challenges of ECGM implementation. For the first time, a consensus statement was offered that made it clear that ECGM needs to be considered as a valuable resource rather than simply an omnipresent option. Furthermore it offers support to clinicians in that the approach that is often perceived as the “safe” choice, namely to put a patient on ECGM, is not always the clinically correct choice.
There can of course be much clinical variation within each type of patient category presented in the statement; it is therefore just a framework for further evaluation. Many clinicians have sought to establish algorithms to determine whether any considered patient should be a candidate for ECGM. Goldman et al developed the most widely studied risk stratification protocols so far [12]. The Goldman criteria focus on chest pain patients and stratify them according to risk into high-, moderate-, low-, and very low-risk categories. The factors associated with an increased risk are 12-lead ECG suggestive of AMI (ST segment elevation or Q waves); 12-lead ECG suggestive of acute ischaemia (ST segment depression or T wave inversion); systolic blood pressure less than 100 mmHg; rales noted bilaterally above the lung bases; pain worse than prior angina or the same as pain experienced with a prior MI. The authors defined a major event as one that required intensive care management. In the first 12 hours of hospitalisation, the rate of new major adverse events occurring in each of the categories was 0.2% (very low), 0.5% (low), 1.1% (moderate), and 7.6% (high). Risk diminished significantly after the first 24 hours. By providing a practical and successful algorithm for implementation of ECGM, the Goldman protocol thus improved the specificity of ECGM as a test (by decreasing ECGM use that resulted in little clinical impact) while maintaining its sensitivity (by continuing ECGM use in patients who would prove to benefit from it). The potential impact of such success on patient outcomes, resource utilisation and financial benefit is great.
Future work and conclusion
The Goldman system was successfully validated internally and much follow-up work has externally validated it as a means of assessing utility for ECGM. However it is only one algorithm for the assessment of one type of patient in whom ECGM is currently implemented. Many similar systems have been developed with varying degrees of success for assessing pre-admission utility of ECGM in patients presenting with other types of illness. It is an ongoing effort in the medical literature to determine which patients are at the highest risk of dysrhythmia and thus how ECGM could and should be utilised in the hospitalised patient.
Indeed, with advances in ECGM functionality including real time ischaemia analysis of dynamic ST segment change as well as QT interval analysis for preemptive arrhythmia recognition, the implementation of ECGM is becoming significantly more complicated rather than less. Outcomes analysis also continues to become more complicated as focus is placed not only on how ECGM best improves patient outcomes, but also increasingly on how its utilisation can meet the challenges of cost efficiency, health system overcrowding and the current medico-legal environment. There is no doubt that Einthoven’s “Le Telecardiogramme” and its ECGM descendants changed medicine forever and continue to do so in new and exciting ways. We must however continue to remain true to Einthoven’s
own practicality, and determine how to utilise ECGM to best serve our patients as well as our healthcare systems.
References
1. Barold SS. Willem Einthoven and the birth of clinical electrocardiography a hundred years ago. Card
Electrophysiol Rev 2003 Jan;7(1):99-104.
2. Einthoven W. Le telecardiogramme. Arch Int Physiol 1906;4:132-164.
3. Fineberg HV, Scadden D, Goldman L. Care of patients with a low probability of acute myocardial infarction. cost effectiveness of alternatives to coronary-care-unit admission. N Engl J Med 1984 May 17;310(20):1301-7.
4. Hollander JE, Valentine SM, McCuskey CF, Brogan GX,Jr. Are monitored telemetry beds necessary for patients with nontraumatic chest pain and normal or nonspecific electrocardiograms?. Am J Cardiol 1997 Apr 15;79(8):1110-1.
5. Saleem MA, McClung JA, Aronow WS, Kannam H. Inpatient telemetry does not need to be used in the management of older patients hospitalized with chest pain at low risk for in-hospital coronary events and mortality. J Gerontol A Biol Sci Med Sci. 2005 May;60(5):605-6.
6. Snider A, Papaleo M, Beldner S, Park C, Katechis D, Galinkin D, et al. Is telemetry monitoring necessary in low-risk suspected acute chest pain syndromes?. Chest 2002 Aug;122(2):517-23.
7. Schull MJ, Redelmeier DA. Continuous electrocardiographic monitoring and cardiac arrest outcomes in 8,932 telemetry ward patients. Acad Emerg Med 2000 Jun;7(6):647-52.
8. Durairaj L, Reilly B, Das K, Smith C, Acob C, Husain S, et al. Emergency department admissions to inpatient cardiac telemetry beds: A prospective cohort study of risk stratification and outcomes. Am J Med 2001 Jan;110(1):7-11.
9. Bayley MD, Schwartz JS, Shofer FS, Weiner M, Sites FD, Traber KB, et al. The financial burden of emergency department congestion and hospital crowding for chest pain patients awaiting admission. Ann Emerg Med 2005 Feb;45(2):110-7.
10. Recommended guidelines for in-hospital cardiac monitoring of adults for detection of arrhythmia. emergency cardiac care committee members. J Am Coll Cardiol 1991 Nov 15;18(6):1431-3.
11. Drew BJ, Califf RM, Funk M, Kaufman ES, Krucoff MW, Laks MM, et al. Practice standards for electrocardiographic monitoring in hospital settings: An american heart association scientific statement from the councils on cardiovascular nursing, clinical cardiology, and cardiovascular disease in the young: Endorsed by the international society of computerized electrocardiology and the american association of critical-care nurses. Circulation 2004 October 26;110(17):2721-46.
12. Goldman L, Cook EF, Johnson PA, Brand DA, Rouan GW, Lee TH. Prediction of the need for intensive care in patients who come to the emergency departments with acute chest pain. N Engl J Med 1996 Jun 6;334(23):1498-504.
The authors
Peter P. Monteleone, MD
Department of Internal Medicine
University of Virginia Health System
Charlottesville, VA 22903, USA
William J. Brady, MD
Department of Emergency Medicine
University of Virginia Health System
Charlottesville, VA 22903 USA
Contact for correspondence:
William J. Brady, MD
email: wb4z@virginia.edu
