Ambulatory Cardiac Telemetry
Abstract & Commentary
By Michael H. Crawford, MD
Source: Kadish AH. Frequency of serious arrhythmias detected with ambulatory cardiac telemetry. Am J Cardiol. 2010;105:
1313-1316.
Ambulatory cardiac telemetry uses a cellular phone monitor to continuously receive transmissions from a sensor on the patient, interpret them, and send ECG strips, considered to be possibly dangerous arrhythmias, to a central station for review and possible intervention. This system has the potential to detect life-threatening arrhythmias and precipitate rapid interventions. This report analyses a nine-month experience with a large system (Life Watch) involving more than 26,000 consecutive patients. The monitor activates when it senses atrial fibrillation, tachycardia, bradycardia, or pauses using preset criteria i.e. ≥ 150 beats/min. for > 10 seconds. After central analysis, physicians are called for certain arrhythmias believed to be dangerous using a tiered action system (emergent, urgent, regular notification). About 80% of the patients presenting had atrial fibrillation, syncope, conduction abnormalities, and palpitation. Physician notification criteria were met in 21% of the patients. Emergent action arrhythmias were present in 1% of patients and urgent arrhythmias in an additional 3%. The authors concluded that only 1% of patients referred for ambulatory cardiac telemetry had life-threatening arrhythmias over a three-week period but, for these patients, this device could be life-saving.
Commentary
For patients at high risk for, or are suspected of having, serious cardiac arrhythmias, various non-invasive devices exist for recording arrhythmias: holter monitors, patient-activated event recorders, automatically activated event recorders, and ambulatory cardiac telemetry. Previous comparison studies have shown that ambulatory cardiac telemetry has the highest yield. An implantable loop recorder would be expected to have a comparable yield, but is invasive and requires interrogation periodically. The major advantage of ambulatory telemetry is that using pre-set criteria, certain arrhythmias can be transmitted to a monitoring station and immediate action can be taken if appropriate. The purpose of this retrospective study was to evaluate the frequency of various rhythm disturbances and assess the potential for life-saving interventions. In this study, only 1% of the patients had such events, which, in this large study, were 260 patients. Of these, 120 had wide complex tachycardias > 15 beats; 100 had pauses ≥ 6
sec; and 40 had sustained rates < 40 beats/min. Not included
in the emergent rhythms, 704 patients had sustained tachycardias > 180 beats/min.
The major limitation of this study is that it was a retrospective analysis of the central-station database. No detailed clinical information or outcomes were known. Of interest, more women than men were monitored (59%), but men had more rhythm disturbances that met physician notification criteria than women (26 vs. 17%, p < 0.001). The fact that almost 80% of patients had nothing worth notifying a physician about is consistent with other ambulatory ECG studies, and suggests that this may be an overused technology. In my experience, most ambulatory ECG studies are ordered by non-cardiologists, probably to protect themselves from lawsuits. Thus, more appropriate use of this technology may be difficult to achieve.
Ambulatory cardiac telemetry uses a cellular phone monitor to continuously receive transmissions from a sensor on the patient, interpret them, and send ECG strips, considered to be possibly dangerous arrhythmias, to a central station for review and possible intervention.You have reached your article limit for the month. Subscribe now to access this article plus other member-only content.
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