I recently cared for a 35-year-old woman who presented to the emergency department for evaluation of palpitations. The symptoms lasted for 10 minutes and produced a mild sense of lightheadedness, but there was no chest pain, dyspnea, diaphoresis, syncope, or other typical cardiopulmonary symptoms. The patient reported that she had palpitations a few times in the prior month, and she had presented to another ED after the first episode. At that time, she had an electrocardiogram that was normal, and she had no further workup. She had no other medical problems, took no medications, and had no primary care physician. I was unable to identify any precipitants for the palpitations: no recent changes in diet, medications, illicit drug use, or stress and no use of tobacco, stimulants, or alcohol. Her physical exam, ECG, and electrolytes were completely normal. The patient I described is not unusual to anyone working in the ED. We often see patients like this and debate the management. Given the absence of significant cardiopulmonary complaints, it would be difficult to justify admission, and even a 24-hour ED observation for cardiac monitoring is likely to be low-yield given the infrequency of her symptoms. My normal approach to this patient would be to recommend that she see her primary care physician or a cardiologist within a day for placement of a Holter monitor or event monitor, but given her lack of a primary care physician and the difficulty of obtaining a rapid appointment within our crowded system, I knew that I was not going to be able to help this patient find a quick diagnosis and treatment.
A Possible Solution?
A solution for scenarios like this may be on the way. The ZIO XT Patch is a single-channel continuous-recording ECG monitor, available by prescription, that can be worn up to 14 days by patients being evaluated for possible cardiac dysrhythmias. As stated in the product manual, “it is indicated for use on patients who may be asymptomatic or who may suffer from transient symptoms such as palpitations, shortness of breach, dizziness, lightheadedness, presyncope, syncope, fatigue, or anxiety.” There are no contraindications to its use.
A major question comes to mind as I consider the future use of this device: given the potential for widespread availability of the device, will the ZIO XT Patch become yet another overused test in very low- or no-risk populations?
The ZIO XT Patch is applied against the left chest using a simple adhesive and fits under normal clothing (the device is approximately 5 inches x 2 inches with a central button that is one-half-inch raised, and it weighs 24.5 grams). It can be worn all day and night and is waterproof, although water exposure should be minimized whenever possible. The device continuously monitors the heart rhythm, but if the patient feels symptoms, a central button can be pressed to mark the recording. At the end of the 14 days, the patient removes the device and mails it in a prepackaged box to a testing facility in Illinois or California, where the rhythm is analyzed and interpreted. Initial cost estimates are less than $200.
Early studies on this device have been very optimistic (although readers must always consider the usual publication bias toward positive studies with new devices). A notable recent study in the Western Journal of Emergency Medicine evaluated 174 patients who had presented to the ED with symptoms of possible cardiac dysrhythmias, most commonly palpitations.1 At the time of discharge, the ZIO XT Patch was applied and worn for up to 14 days or until the patient had symptoms to trigger an event. The overall diagnostic yield for detection of a dysrhythmia was 63 percent. Almost half the patients (48 percent) were noted to have at least one significant dysrhythmia event, defined as ventricular tachycardia, paroxysmal atrial fibrillation, supraventricular tachycardia, >3 second pause, Mobitz II, third-degree AV block, or symptomatic bradycardia. Of note, only 10 percent of patients with significant dysrhythmias were symptomatic at the time of their dysrhythmia, suggesting that traditional event recorders, which rely on patients’ recognition of symptoms, would have failed to detect these episodes. Equally important was the finding that 53 percent of symptomatic patients did not have any dysrhythmias during their triggered events, indicating a non-dysrhythmic cause of symptoms. The median time to first detection of dysrhythmia was one day (interquartile range 0.2–2.8 days), and the median time to first symptomatic event was 1.5 days (interquartile range 0.4–6.7 days), suggesting that traditional 48-hour Holter monitors would have detected a majority, but not all, of the dysrhythmias. The ZIO XT Patch offers a promising alternative to Holter or event monitors for the outpatient evaluation of patients with possible dysrhythmias. However, a major question comes to mind as I consider the future use of this device: given the potential for widespread availability of the device, will the ZIO XT Patch become yet another overused test in very low- or no-risk populations? If this occurs, we’ll undoubtedly encounter an explosion of false-positive results, which could lead to further unnecessary testing and procedures. We’ve already seen this occur with other diagnostic tests, including the D-dimer, cardiac stress tests, the highly sensitive troponins, and coronary CT angiograms. I look forward to reading further studies on this device and hearing the debates that will certainly follow.