Role of extended external loop recorders for the diagnosis of unexplained syncope, pre-syncope, and sustained...

To assess the diagnostic yield of new external loop recorders (ELRs) in patients with history of syncope, pre-syncope, and sustained palpitations.

Since 2005, we have established a registry including patients who consecutively received ELR monitoring for unexplained syncope or pre-syncope/palpitations. The registry included 307 patients (61% females, age 58 ± 19 years, range 8-94 years) monitored by high-capacity memory ELR of two subsequent generations: SpiderFlash-A(®) (SFA(®), Sorin CRM), storing two-lead electrocardiogram (ECG) patient-activated recordings by loop-recording technique (191 patients, 54 patients with syncope, years 2005-09), and SpiderFlash-T(®) (SFT(®)), adding auto-trigger detection for pauses, bradycardia, and supraventricular/ventricular arrhythmias (116 patients, 38 patients with syncope, years 2009-12). All the patients previously underwent routine workup for syncope or palpitation, including one or more 24 h Holter, not conclusive for diagnosis. Mean monitoring duration was 24.1 ± 8.9 days. Among 215 patients with palpitations, a conclusive diagnosis was obtained in 184 patients (86% diagnostic yield for palpitation). Among 92 patients with syncope, a conclusive diagnosis was obtained in 16 patients (17% clinical diagnostic yield for syncope), with recording during syncope of significant arrhythmias in 9 patients, and sinus rhythm in 7 patients. Furthermore, asymptomatic arrhythmias were de novo detected in 12 patients (13%), mainly by auto-trigger detection, suggesting an arrhythmic origin of the syncope.

The diagnostic yield of ELR in patients with syncope, pre-syncope, or palpitation of unknown origin after routine workup was similar to implantable loop recorder (ILR) within the same timeframe, therefore, ELR could be considered for patients candidate for long-term ECG monitoring, stepwise before ILR.