Case Study: Diagnosis and Management of Infrequent Syncope

Case Description

A 33-year-old woman presented for another opinion regarding her symptoms that she believed were due to arrhythmia. She had previously been seen by three physicians and was told she most likely was suffering from panic attacks, as her evaluation thus far had been unremarkable. The patient stated that in 2010, approximately three months after her first pregnancy, she began experiencing episodes of dizziness and near syncope. Episodes occurred approximately every 5-6 weeks for a few months, and then resolved. These episodes would last approximately five minutes. She described feeling a rapid heartbeat, lightheadedness, pressure in the substernal area, and associated shortness of breath. She noted that at times these symptoms were severe enough that she felt as though she might pass out. At the time she was evaluated, she was found to have a normal electrocardiogram, normal echocardiogram, and no arrhythmia seen on 24-hour Holter monitor.

She did well after that, with no subsequent episodes until after the birth of her second child in July 2014, when she again started experiencing dizzy spells. She described these as being more severe than the prior episodes, including that they lasted longer (now up to 30 minutes), she felt her heart beating faster, and she was also more lightheaded than with the prior episodes. Episodes occurred every 4-6 weeks.

She presented to the ER numerous times, with the symptoms resolving prior to arrival at the ER. Numerous electrocardiogram assessments were all normal. The patient also wore a 30-day external loop recorder, which was also normal. The patient described not having episodes of her symptoms while wearing the monitor. She was again told that she was most likely suffering from anxiety and panic attacks. Despite anxiolytic medication, she continued to have dramatic episodes. Her continued symptoms led her to seek yet another opinion.

The patient has no significant past medical history other than her two uneventful pregnancies and deliveries. She takes no regular medications. She denies alcohol, tobacco, or recreational drug use. She has no family history of heart disease, sudden cardiac death, or unexplained death.

Her physical exam was entirely normal. Review of her numerous electrocardiograms showed them to be normal. There was no evidence of pre-excitation. All intervals measured normal. Echocardiogram was normal. Review of her 24-hour and 30-day ambulatory monitors revealed no arrhythmias other than occasional PACs.

With continued symptoms suggesting an underlying arrhythmia, no structural heart disease, and episodes occurring more than a month apart, the patient was offered an implantable cardiac monitor to allow continuous, long-term heart rhythm monitoring. A Reveal LINQ Insertable Cardiac Monitor (Medtronic, Inc.) was implanted in September 2014.

Approximately seven weeks later, she experienced another episode which she described as a typical episode for her, lasting approximately 90 seconds. She described the sensation of her heart racing as well as lightheadedness and shortness of breath. The implantable monitor detected this episode and automatically recorded it. The episode was also then automatically transmitted that night through the patient’s MyCareLink bedside monitor (Medtronic, Inc.). Review of this episode showed she experienced an episode of atrial fibrillation with very rapid conduction (ventricular rates nearing 300 beats per minute). (Figure 1)

The patient was seen the next day, and was counselled on pharmacologic and ablation therapies. The patient has opted to pursue ablation. The implantable cardiac monitor will remain in place to monitor the success of the anticipated ablation.

Discussion

This case demonstrates a not uncommon situation when patients experience recurrent yet infrequent episodes of arrhythmia. The yield of short-term (24 hour) or medium-term (30-day) heart monitors is low when patients infrequently experience symptoms (greater than four weeks apart). The patient described here had never lost consciousness during her episodes, yet felt as though she might at times. The 2009 ESC guidelines for the diagnosis and management of syncope outline that ambulatory ECG monitoring should be selected according to the risk and predicted recurrence of episodes.¹ In this patient’s case, since the episodes occurred more than four weeks apart, the monitor with the highest yield was the long-term implantable cardiac monitor. ■

Disclosure: Outside the submitted work, Dr. Rogers reports speaking/consulting fees from Medtronic.   

Reference

1. Moya A, Sutton R, Ammirati R, et al. Guidelines for the diagnosis and management of syncope (version 2009). Eur Heart J. 2009;30(21):2631-2671.