Case Study

Using a Novel Cardiac Monitor to Find the Cause of Syncope: The Diagnosis is Only as Good as the Data

James Stone, MD

North Mississippi Medical Center

Tupelo, Mississippi

James Stone, MD

North Mississippi Medical Center

Tupelo, Mississippi

Syncope can be one of the most challenging symptoms to manage because its etiology is wide ranging. In some cases, syncope resolves on its own with little problem. In other cases, it may indicate imminent cardiac arrest or be the harbinger of serious heart disease.1 When treating syncopal patients, particularly the elderly or those with risk factors for heart disease, it is crucial to take these symptoms seriously, but getting comprehensive and reliable data on which to base a diagnosis can be difficult.

Case Description

The patient is an 86-year-old African-American woman who enjoys going to the hairdresser, attending church, and being among family and friends. However, when getting her hair done, she would often pass out and then regain consciousness a few seconds later. Since she was always seated when this happened, she never fell or injured herself, but the staff at the salon became increasingly worried about her. When she regained consciousness, she had no memory of what happened and would trivialize the event. Fortunately, her syncopal spells were witnessed events and the family soon learned about the episodes, which had become more frequent. Reluctantly, the patient came in for an appointment to find out why she kept passing out.

A complete cardiac workup revealed nothing that would explain the events. She had no ischemia or structural heart disease. Since her spells were intermittent, a Holter monitor was ordered. However, use of a Holter monitor is not always optimal — the devices can be bulky and cumbersome, and do not always reveal clinically actionable data given the limited duration of their use (particularly if episodes are infrequent). Also, compliance can be suboptimal due to numerous factors.

After the Holter monitor did not produce any useful findings, we chose the BIOMONITOR III (BIOTRONIK), an injectable cardiac monitor, for this patient. There are currently a number of implantable monitors on the market, so clinicians must balance patient comfort versus signal fidelity and/or detection accuracy. Administration is simple, and can often be inserted in a few minutes in the outpatient setting with a local anesthetic. However, in a super-small monitor, the electrode spacing is often less than ideal in terms of getting a strong, reliable, true signal. The BIOMONITOR III device has excellent signal integrity, and its novel design and implantation tool makes it easy to implant.

The patient’s obesity was also a consideration, since implantable monitors in large patients can sometimes lose signals and generate false-positives, which in turn, can lead to inaccurate diagnoses. Treating syncope requires an accurate diagnosis. Therefore, the BIOMONITOR III was selected since its longer signal vector can be less prone to signal dropouts and false-positive asystole detections, as compared to devices with smaller signal vectors.

The BIOMONITOR III was injected at the outpatient facility under local anesthetic in a few minutes. This innovative injection technique allows the device to be inserted subcutaneously in a simple step with minimal patient discomfort. The incision was closed with staples. (Figure 1)

The patient was given a Home Monitoring system (BIOTRONIK), which is used to transmit alerts and important information back to the clinic with no direct patient intervention. Patients can initiate recordings from the Home Monitoring system, but since this patient was unaware of her syncopal episodes, it was clear that an automatic monitoring system would work better for her.

After about four weeks of unremarkable cardiac activity and no syncopal spells, the recordings started to show a few asystolic episodes, which became increasingly frequent. The Episode List from the diagnostics showed 26 detected asystoles in 21 days. The asystolic episodes were three to five seconds in length and resolved spontaneously. The patient did not remember anything unusual during those episodes, but the data showed that as many as three asystolic episodes occurred in one day (Figure 2).

Further assessment also revealed sinus node dysfunction combined with second-degree heart block. A dual-chamber pacemaker (Edora 8 DR-T with Closed Loop Stimulation and ProMRI AutoDetect capabilities, BIOTRONIK) was implanted in an uneventful procedure. The patient has made a full recovery, and is well adjusted to her pacemaker.

Discussion

The BIOMONITOR III allowed an accurate diagnosis in this case, because it provided detailed data and alerted the clinic about the asystole. Using this data, it was evident that the patient’s symptoms were due to bradyarrhythmias and the patient was able to get the proper therapy. Without the benefit of this monitoring, it might have taken much longer to get these asystolic periods recorded.

Heart disease is a leading cause of death for women and is responsible for 25% of all deaths of American women.2 Just as with men, the risks of heart disease for women increase with advancing age. Yet, not all women are aware that the symptoms might indicate a cardiac condition, or they may downplay these symptoms. In fact, many women do not think of themselves as at risk for heart disease at all.

Asystole can be the terminal rhythm of cardiac arrest, but in this particular patient, normal rhythm resumed after short episodes of a few seconds each. This suggests that her asystole was the result of conduction problems. Although she recovered quickly, the episodes still posed considerable risk. Hypoperfusion occurs during each episode of asystole, and the effects of this loss of oxygen are cumulative, making it important to diagnose and treat these episodes as quickly as possible.

The etiology of asystole is varied and may be caused by an underlying illness, cardiac arrest, certain drugs,3,4 the peri-ictal period following seizure,5 or other conditions.6 In the case of this patient, the relatively rapid recovery of normal rhythm after asystole implicated cardiac conduction disorder as a potential cause. This was confirmed by data obtained from Home Monitoring and subsequent examinations, which showed she had indications for a dual-chamber pacemaker.

The most crucial aspect in treating this type of conduction-related asystole is rapid and accurate diagnosis, since an incorrect diagnosis might delay effective treatment and put the patient at risk. The role of the implantable recorder is crucial, because it gathers more data and presents it in an easier-to-analyze format than Holter or event monitors. The BIOMONITOR III has excellent signal integrity and is easy to inject. A recent study also found the use of the BIOMONITOR to be cost effective for the detection of clinically silent atrial fibrillation in patients with cryptogenic stroke.7 The BIOMONITOR III generates ample high-quality data, provides excellent signal resolution, offers a Home Monitoring alert function to ensure important episodes are not overlooked, and offers a less expensive and less burdensome option to the patient than Holter monitoring.

Summary

In all EP cases, the diagnosis is only as good as the data. The high degree of signal fidelity of the BIOMONITOR III and its under-the-skin, round-the-clock surveillance provided the data needed to make a swift diagnosis and allow this patient to get the treatment needed in order to restore both normal heart rhythm and better quality of life. 

Disclosure: Outside the submitted work, Dr. Stone reports compensation from BIOTRONIK for lectures, as well as compensation from Boston Scientific for physician training and proctoring of cases. Medical writer Jo Ann LeQuang helped edit this article; her services were paid by BIOTRONIK.

This article is published with support from BIOTRONIK.

References
  1. Grubb BP, Olshansky B. Syncope: Mechanisms and Management, Second Edition. Malden, MA: Wiley-Blackwell; 2005.
  2. Xu J, Murphy S, Kochanek M, Baian B, Arias E. Deaths: Final Data for 2016. National Vital Statistics Reports. Published July 26, 2018. Available at https://www.cdc.gov/nchs/data/nvsr/nvsr67/nvsr67_05.pdf. Accessed May 16, 2019.
  3. Aronson JK. Chapter 35 - Drugs that affect blood coagulation, fibrinolysis, and hemostasis. In: Aronson JK, ed. Side Effects of Drugs Annual. Vol 33. Elsevier; 2011:707-739.
  4. Toussaint KA, Gallagher JC. Chapter 25 - Penicillins, cephalosporins, other beta-lactam antibiotics, and tetracyclines. In: Aronson JK, ed. Side Effects of Drugs Annual. Vol 35. Elsevier; 2014:447-461.
  5. Groh WJ. 100 - Arrhythmias in Patients With Neurologic Disorders. In: Zipes DP, Jalife J, eds. Cardiac Electrophysiology: From Cell to Bedside (Sixth Edition). Philadelphia: W.B. Saunders; 2013:993-999.
  6. Boatman EA. Asystole. In: Bready LL, Dillman D, Noorily SH, eds. Decision Making in Anesthesiology (Fourth Edition). Philadelphia: Mosby; 2007:74-75.
  7. Maervoet J, Bossers N, Borge R Jr., Hilpert S, van Engen A, Smala A. Use of insertable cardiac monitors for the detection of atrial fibrillation in patients with crypotegenic stroke in the United States is cost-effective. J Med Econ. 2019;22:1221-1234.
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