Experience With Implantable Loop Recorders for Recurrent Unexplained Syncope

Knowledge of what occurs during spontaneous syncope is the gold standard for evaluation. Initially, implantable loop recorders (ILRs) were used in patients with unexplained syncope at the end of unsuccessful full, conventional work-up. In pooled data regarding 247 patients, a correlation between syncope and electrocardiographic findings was found in 84 patients (34%); of these, 52% had a bradycardia or asystole at the time of the recorded event, 11% had tachycardia, and 37% had no arrhythmia. Presyncope-electrocardiography correlation was observed in another third of the patients; presyncope was much less likely to be associated with an arrhythmia than was syncope. The diagnostic yield was similar in patients with and without structural heart diseases and was higher in older than in younger patients. Recent studies showed that ILR implantation can be safely performed in an early phase of the diagnostic evaluation--provided that patients at risk for life-threatening events are carefully excluded--in the patients who have a severe presentation of syncope (because of high risk of trauma or high frequency of episodes) which can be a benefit of a mechanism-specific therapy.