Telemetry—from the Greek words tele (remote) and metron (measure)—for cardiac monitoring was developed in the mid-1960s by Spacelabs Medical for use in spaceflight.1 The system was later adopted in hospitals to detect life-threatening arrhythmias.
Guidelines for the use of telemetry were published in 1991 by the American College of Cardiology (ACC)2 in response to concerns raised by its increasing use in noncritical care settings during the 30 years after its introduction to clinical medicine. The latest revision of the guidelines was published in 2004 by the American Heart Association (AHA).3
However, the guidelines are based largely on expert opinion and on research data in electrocardiography. Few clinical trials of telemetry have been published, and they were either retrospective or nonrandomized. In fact, there were no published randomized trials at the time the 2004 guidelines were written. Moreover, very few of these studies evaluated the impact of cardiac telemetry monitoring on physician management decisions.
We reviewed the literature to find out how cardiac telemetry is being used in clinical practice and how it might be used more selectively. The literature search was performed using Ovid MEDLINE (1996 to present) and PubMed Central using the key search terms “cardiac monitoring,” “telemetry monitoring,” “telemetry,” and “inpatient.” References from articles identified using Ovid MEDLINE (1996 to present) and PubMed Central that were relevant to our review were also included.
THREE CLASSES OF RISK
- Class II consists of patients for whom cardiac monitoring may be of benefit in some cases but is not essential for all (Table 2).
PATIENTS AT LOW RISK DO NOT BENEFIT
Telemetry monitoring has become an essential and commonly used clinical tool in most hospital systems. However, physicians do not seem to be using the risk stratification guidelines routinely or appropriately. The result is that many patients are being monitored needlessly, because telemetric monitoring neither affects how patients at low risk are managed nor improves their clinical outcomes.
Saleem et al4 reported that, of 105 patients at low risk who presented with chest pain and were admitted to a telemetry unit, none experienced a cardiac event or arrhythmia warranting changes in management while in the hospital.
Durairaj et al5 conducted a prospective cohort study of 1,033 patients admitted consecutively from an emergency department to an inpatient telemetry unit from July 1998 to January 1999. Patients were initially stratified according to a prediction model proposed by Goldman et al6 into groups at high, moderate, low, and very low risk. The risk groups were substratified according to the presence or absence of chest pain. The outcomes measured were transfer to an intensive care unit and a major cardiac complication, which included acute myocardial infarction, cardiac arrest, ventricular fibrillation, temporary pacemaker implantation, cardiogenic shock, emergency cardioversion, use of an intraaortic balloon assist device, intubation, and recurrent ischemic pain requiring coronary revascularization within 72 hours after admission or requiring cardiac catheterization followed by coronary revascularization before discharge from the hospital. The subgroup of patients who were classified as being at very low risk and who did not have chest pain (n = 318) did not experience any major cardiac complication.
Sivaram and colleagues7 studied the role of telemetric monitoring in the management of patients with class I, II, and III indications for telemetric monitoring outside of critical care units. The class was assigned at the time of discharge for the purpose of the study. A total of 297 telemetry events were noted during the study, but only 12 (4%) of the events led to changes in patient management: a change in medication in 8 patients, cardioversion for unstable atrial flutter in 1 patient, insertion of a pacemaker for sinus pause in 1, and electrophysiology studies in 2 patients.
Estrada et al8 examined the clinical outcomes of 2,240 patients admitted to a non-intensive care unit. The physicians perceived telemetric monitoring as helpful in 283 (12.6%) of the patients. However, data obtained from telemetry monitoring directly affected management decisions in only 156 patients (7% of the original study population). The researchers concluded that physicians may overestimate the role of telemetry in guiding patient management.
Hollander et al9 examined the outcomes of 261 patients admitted because of chest pain who had normal or nonspecific findings on electrocardiography on presentation. Only 4 patients (1.5%) experienced arrhythmias. The authors concluded that the policy of admitting patients at low risk to monitored beds should be reevaluated.
Snider et al10 showed that patients presenting with atypical chest pain and normal electrocardiographic findings were at low risk of arrhythmias and did not benefit from telemetric monitoring.
Schull and Redelmeier11 performed a 5-year observational study in which they reviewed all telemetry admissions (N = 8,932) to a tertiary care facility. Twenty patients experienced cardiac arrest during the study period, but telemetric monitoring was in use at the time in only 16 of the 20. Furthermore, the telemetry monitors signalled the onset of cardiac arrest in only 9 of these 16 patients. Three of the patients whose hearts stopped beating survived until discharge: two in whom telemetry actually signalled the onset of cardiac arrest and one in whom it did not.