Syncope associated with supraventricular tachycardia: Diagnostic role of implantable loop recorders

Abstract

Syncope represents a relatively uncommon symptom of supraventricular tachycardia (SVT). It is likely that an impaired autonomic vasomotor response to the hemodynamic stress of tachycardia is the determinant of hemodynamic changes leading to cerebral hypoperfusion and syncope. In this regard, tilt‐table test may detect abnormalities in the autonomic nervous function and predict the occurrence of syncope during SVT. Electrophysiology studies may reproduce the SVT, distinguish it from other life‐threatening ventricular tachyarrhythmias, and exclude other causes of syncope. Not infrequently mixed syncope mechanisms are revealed during the above diagnostic workup raising doubts about the operating mechanism in the clinical setting. In such cases of uncertainty, an implantable loop recorder, providing long‐term cardiac monitoring, may play a pivotal role in the establishment of the diagnosis, confirming the association of an arrhythmic event with the symptom. Herein, we present four such cases with recurrent unexplained syncope finally attributed to paroxysmal SVT guiding them to a potentially radical treatment through radiofrequency catheter ablation.

How Should We Approach Syncope in the Emergency Department? Current Perspectives

“…Open Access Emergency Medicine 2022:14 302 a clear cause for syncope and who have typical complaints of SVTs but no documented ECG referral to a syncope clinic for 24-hour Holter monitorization or implantable loop recorders might be beneficial to diagnose the presence of SVTs and to differentiate between its various forms. 18 Brugada syndrome is an inherited cardiac disease that can cause ventricular arrhythmias. Three types of Brugada pattern are defined and type 1 carries the high risk for malignant syncope.…”

Unexplained Syncope: The Importance of the Electrophysiology Study

“…If the episodes are recurrent and remain unexplained with a negative tilt table test, then special diagnostic techniques of long-term electrocardiographic recording (implantable loop recorder) can be applied, which occasionally reveals the cause and mechanism of these episodes [37][38][39][40][41]. These patients should also be suspected of having a psychiatric condition [42][43][44][45], provided a thorough electrophysiology investigation has ruled out the presence of a life threatening and provocative arrhythmia substrate, which can be safely and adequately addressed even among such patients [46].…”

“…Although epilepsy is not considered syncope, as it is not associated with transient loss of consciousness, there are reported cases of epilepsy patients responding to antibradycardia pacing [47] while it is well known that some epilepsy patients die suddenly implicating arrhythmia mechanism of central origin [48]. It is uncommon to encounter syncopal patients exhibiting several syncope mechanisms, either benign or potentially malignant during a thorough diagnostic approach [41]. In such cases, the operating mechanism may be revealed by an implantable loop recorder, thus, leading the patient to the safest and most appropriate treatment plan [41].…”

“…It is uncommon to encounter syncopal patients exhibiting several syncope mechanisms, either benign or potentially malignant during a thorough diagnostic approach [41]. In such cases, the operating mechanism may be revealed by an implantable loop recorder, thus, leading the patient to the safest and most appropriate treatment plan [41].…”

“…Based on the diagnostic approach analyzed above, at the "Hippokration" General Hospital of Athens, we follow a two-step diagnostic approach [27,41,49,50]. In the first step, which is the non-invasive one, the goal is to increase the sensitivity of the simple 12-lead surface electrocardiogram in combination with signal-averaged electrocardiogram (SAECG) and the 24-h Holter monitoring.…”