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A 38-Year-Old Man With Obesity, Intermittent Tachycardia, and One Episode of SyncopeImplantable Loop Recorder Tales FREE TO VIEW

Karolina K. Marinescu, MD; Mazhar Khan, MD; James A. Rowley, MD, FCCP; Teferi Y. Mitiku, MD
Author and Funding Information

From the Division of Cardiovascular Medicine (Drs Marinescu, Khan, and Mitiku) and Division of Pulmonary, Critical Care & Sleep Medicine (Dr Rowley), School of Medicine, Wayne State University, Detroit, MI.

CORRESPONDENCE TO: Karolina K. Marinescu, MD, School of Medicine, Wayne State University, Harper University Hospital, 8 Brush, Detroit, MI 48201; e-mail: Kmirowsk@med.wayne.edu


Reproduction of this article is prohibited without written permission from the American College of Chest Physicians. See online for more details.


Chest. 2015;148(1):e22-e25. doi:10.1378/chest.14-1812
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A 38-year-old man with history of diabetes, hypertension, hyperlipidemia, and obesity was referred to the electrophysiology clinic for evaluation of infrequent palpitations and remote history of syncope. The patient described a sensation of racing of the heart, which lasted about 30 min to 1 h and occurred several times over the past year. This was associated with a sense of anxiety and shortness of breath and appeared to resolve spontaneously. The patient also experienced one episode of syncope in the past while enjoying a barbecue on a hot summer day. He did not recall if this episode was accompanied by palpitations, however, the previously mentioned symptoms prompted the consultation. Upon further questioning the patient also reported experiencing fatigue. He stated that he noted decreased energy and frequent daytime sleepiness.

Figures in this Article

The patient was 1.6 m tall and weighed 108.9 kg with a BMI of 40. The measurement of vital signs showed the following: BP, 125/78 mm Hg; heart rate, 98 beats/min; respiratory rate, 18 breaths/min; and oxygen saturation, 98% on room air. The patient was alert, oriented, and in no acute distress. Examination of the head, ears, eyes, nose, throat, lungs, heart, and extremities revealed normal jugular venous pressure without distention; clear lungs with good respiratory effort; regular rate and rhythm with no murmurs, rubs, or gallops; and absence of clubbing, cyanosis, or edema.

A comprehensive metabolic panel showed the following values: sodium, 144 mM; potassium, 4.5 mM; chloride, 105 mM; bicarbonate, 30 mM; BUN, 11 mg/dL; creatinine, 1.1 mg/dL; total cholesterol, 126 mg/dL; high-density lipoprotein, 29 mg/dL; low-density lipoprotein, 63 mg/dL; thyroid-stimulating hormone, 3.35 μIU/mL; and troponin, < 0.04 ng/mL. A 12-lead ECG showed a normal sinus rhythm, normal axis, with nonspecific T-wave inversions in inferior leads (Fig 1). An echocardiogram showed normal left ventricular size, thickness, and systolic function, with no wall motion abnormalities. The valvular structures were normal, however, tricuspid valve regurgitation Doppler data were suboptimal precluding comments on pulmonary pressures.

Figure Jump LinkFigure 1 –  Normal sinus rhythm, normal axis, nonspecific T-wave inversions in inferior leads. aVF = augmented vector foot; aVL = augmented vector left; aVR = augmented vector right.Grahic Jump Location

Since the patient’s symptoms were rare, the decision was made to proceed with an implantable loop recorder (ILR). Device interrogation on follow-up testing showed episodes of supraventricular tachycardia during wake hours. Interestingly, there were also recurrent short bursts of profound sinus bradycardia during sleep, followed by sudden increases in heart rate, which were noted to be sinus tachycardia (Fig 2).

Figure Jump LinkFigure 2 –  Arrhythmia recorded during sleep. The patient was noted to be in sinus rhythm with variable heart rates (HRs) as seen by the cyclical changes in the RR interval, measures in ms (RR interval of 1,500 ms corresponds to HR of 40, whereas RR interval of 700 ms corresponds to HR of 88). bpm = beats/min; Max V = maximum ventricular rate; Median V = median ventricular rate.Grahic Jump Location
What is the underlying cause of the arrhythmias occurring during sleep?
Diagnosis: OSA

OSA is the most common of the sleep-related breathing disorders. The disorder has an estimated prevalence in North America of approximately 15% in men and 5% in women. Patients with OSA frequently experience various cardiac rhythm disturbances, of which cyclical variation in heart rate (CVHR) is most commonplace. As initially described in the early 1970s by Guilleminault and colleagues, it is currently believed that during apneic episodes there is increased respiratory effort against a closed glottis associated with hypoxemia, resulting in an increase in parasympathetic stimulation and a relative slowing of the heart rate proportional to the amount of parasympathetic tone. The patient experiences a brief arousal, when parasympathetic tone is abruptly withdrawn and there is an increase in sympathetic tone and relative tachycardia. This cycle repeats itself with each obstructive apnea and hypopnea event.

Of course, CVHR is not the only arrhythmia noted in patients with OSA. While many arrhythmias, including bradycardia and sinus pauses, have been associated with OSA in the literature in well-performed studies correcting for confounders, OSA is associated primarily with increased odds of having atrial fibrillation, nonsustained ventricular tachycardia, and complex ectopy (defined as nonsustained ventricular tachycardia or bigeminy or trigeminy or quadrigeminy). The association between atrial fibrillation and OSA has been extensively studied, with most studies suggesting both increased prevalence and poorer control of atrial fibrillation. Studies also suggest that catheter ablation with subsequent rate and rhythm control is most successful in patients being treated for OSA with CPAP. The presence and severity of these disorders carry their own implications regarding morbidity and mortality.

Since their introduction in the early 1990s, implantable ECG monitoring devices have proven to be a useful tool in diagnosing many arrhythmia-related ailments. They are most commonly used in the workup of recurrent syncope, tachyarrhythmias and bradyarrhythmias, and palpitations. The small size, relatively low cost, long battery life (long recording capacity), and easy implantation with very low complication rates make the ILR a very attractive diagnostic tool. However, the wealth of information provided by this device extends beyond cardiac disease.

The increased diagnostic yield of ILRs in diagnosing a variety of cardiac conditions (such as presyncope, syncope, and recurrent palpitations) is well recognized. In the case of recurrent syncope and presyncope, longer monitoring times increase diagnostic yield by as much as threefold. In fact, ILRs may provide the diagnosis in cases where many other, often times more expensive, modalities failed to do so. It is not uncommon for a patient to be evaluated by several clinicians and be subjected to many diagnostic modalities (CT scans, MRIs, EEG, etc) without obtaining the diagnosis. In such patients, ILRs yielded the diagnosis almost 80% of the time. This, in turn, can have significant implications, as therapeutic choices for those affected by recurrent syncope can help prevent future episodes, and thereby will lead to significant improvements in morbidity and mortality.

Furthermore, the clinical indications for ILRs are expanding. Many have suggested that there is substantial utility in the use of ILRs for detection and monitoring of atrial fibrillation, which may be useful in guiding therapeutic management choices. Additionally, ILRs may be used to identify patients at high risk for fatal arrhythmias—patients with long or short QT syndrome, Brugada ECG pattern, and those with cardiomyopathies such as hypertrophic obstructive cardiomyopathy and arrhythmogenic right ventricular cardiomyopathy. Moreover, ILRs provide insight into the epidemiology of various arrhythmias and prove to be a useful tool in clinical research of arrhythmias. Lastly, these devices may also provide incidental findings not related to initial indication for device placement, which may be clinically relevant. Diseases that may otherwise go undiagnosed can have significant morbidity and mortality. Thus, the information collected may have therapeutic implications. As in the case of this patient, CVHR seen during sleep raised suspicion for OSA and is often unrecognized. The period of upper airway collapse leads to frequent arousals from sleep and subsequent daytime sleepiness, which translates to loss of productivity and decreased quality of life. Patients with OSA have a significant increase in the prevalence of hypertension in those with OSA which was dose dependent, as prevalence of hypertension increases in proportion to severity of OSA. OSA has also been associated with the development of both fatal and nonfatal cardiovascular disease (including congestive heart failure, coronary heart disease, and cerebrovascular disease), and successful treatment of OSA decreases this risk significantly.

As the use of ILRs continues to expand, the diagnostic information provided is likely to continue to grow and spill over into other areas of medicine. Once embedded under the skin, their small size allows for aesthetically acceptable results to patients. The relatively simple placement procedure (with an extremely low risk of complications), the large amount of data that can be recorded, and the long battery life make the device attractive to clinicians. As the use of ILRs continues to broaden, the number of incidental findings is likely to increase. Many of those so-called “incidentalomas” may in fact have crucial impacts on patients’ diagnoses, therapies, and, ultimately, outcomes.

Clinical Course

Given the findings provided by the ILR, the patient underwent a sleep study, which confirmed the diagnosis. He was subsequently fitted for a CPAP machine. He is tolerating the therapy and, on subsequent evaluations of the ILR tracings, the previously mentioned CVHR improved significantly, as did the self-reported quality of sleep (Fig 3).

Figure Jump LinkFigure 3 –  Heart rate recorded after initiation of CPAP therapy. See Figure 2 legend for expansion of abbreviations.Grahic Jump Location

  • 1. Patients with sleep disorders, such as OSA, frequently develop cardiac arrhythmias, the most frequent of which is CVHR.

  • 2. OSA is a treatable disorder and is, thus, a readily modifiable risk factor for development of cardiac disease.

  • 3. In patients with OSA and atrial fibrillation, treatment of OSA leads to significant improvement in rhythm control after ablation.

  • 4. The ILR provides an elegant way of establishing the diagnosis, correlating the symptoms, and monitoring the treatment of those patients with electrophysiologic disorders. This case identified a cardiac rhythm frequently seen in patients with untreated OSA.

  • 5. As demonstrated by this patient’s scenario, ILRs are ideal for monitoring patients with a variety of conditions in the outpatient, “real-world” setting, and thus are likely to become the first step in the emerging field of long-term physiologic monitoring devices.

Financial/nonfinancial disclosures: The authors have reported to CHEST that no potential conflicts of interest exist with any companies/organizations whose products or services may be discussed in this article.

Other contributions: CHEST worked with the authors to ensure that the Journal policies on patient consent to report information were met.

Guilleminault C, Tilkian A, Dement WC. The sleep apnea syndromes. Ann Rev Med. 1976;27:465-484. [CrossRef] [PubMed]
 
Gula LJ, Krahn AD, Skanes AC, Yee R, Klein GJ. Clinical relevance of arrhythmias during sleep: guidance for clinicians. Heart. 2004;90(3):347-352. [CrossRef] [PubMed]
 
Mehra R, Benjamin EJ, Shahar E, et al; Sleep Heart Health Study. Association of nocturnal arrhythmias with sleep-disordered breathing: the Sleep Heart Health Study. Am J Respir Crit Care Med. 2006;173(8):910-916. [CrossRef] [PubMed]
 
Brignole M, Vardas P, Hoffman E, et al; Task Force members; EHRA Scientific Documents Committee; Document Reviewers; EHRA Scientific Documents Committee. Indications for the use of diagnostic implantable and external ECG loop recorders. Europace. 2009;11(5):671-687. [CrossRef] [PubMed]
 
Li L, Wang ZW, Li J, et al. Efficacy of catheter ablation of atrial fibrillation in patients with obstructive sleep apnoea with and without continuous positive airway pressure treatment: a meta-analysis of observational studies. Europace. 2014;16(9):1309-1314. [CrossRef] [PubMed]
 

Figures

Figure Jump LinkFigure 1 –  Normal sinus rhythm, normal axis, nonspecific T-wave inversions in inferior leads. aVF = augmented vector foot; aVL = augmented vector left; aVR = augmented vector right.Grahic Jump Location
Figure Jump LinkFigure 2 –  Arrhythmia recorded during sleep. The patient was noted to be in sinus rhythm with variable heart rates (HRs) as seen by the cyclical changes in the RR interval, measures in ms (RR interval of 1,500 ms corresponds to HR of 40, whereas RR interval of 700 ms corresponds to HR of 88). bpm = beats/min; Max V = maximum ventricular rate; Median V = median ventricular rate.Grahic Jump Location
Figure Jump LinkFigure 3 –  Heart rate recorded after initiation of CPAP therapy. See Figure 2 legend for expansion of abbreviations.Grahic Jump Location

Tables

Suggested Readings

Guilleminault C, Tilkian A, Dement WC. The sleep apnea syndromes. Ann Rev Med. 1976;27:465-484. [CrossRef] [PubMed]
 
Gula LJ, Krahn AD, Skanes AC, Yee R, Klein GJ. Clinical relevance of arrhythmias during sleep: guidance for clinicians. Heart. 2004;90(3):347-352. [CrossRef] [PubMed]
 
Mehra R, Benjamin EJ, Shahar E, et al; Sleep Heart Health Study. Association of nocturnal arrhythmias with sleep-disordered breathing: the Sleep Heart Health Study. Am J Respir Crit Care Med. 2006;173(8):910-916. [CrossRef] [PubMed]
 
Brignole M, Vardas P, Hoffman E, et al; Task Force members; EHRA Scientific Documents Committee; Document Reviewers; EHRA Scientific Documents Committee. Indications for the use of diagnostic implantable and external ECG loop recorders. Europace. 2009;11(5):671-687. [CrossRef] [PubMed]
 
Li L, Wang ZW, Li J, et al. Efficacy of catheter ablation of atrial fibrillation in patients with obstructive sleep apnoea with and without continuous positive airway pressure treatment: a meta-analysis of observational studies. Europace. 2014;16(9):1309-1314. [CrossRef] [PubMed]
 
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