Use of an extended monitoring strategy in patients with problematic syncope

Background-The conventional investigation of patients who present with sync ope involves short-term ECG monitoring or provocative testing with head-up tilt and electrophysiological testing. A symptom-rhythm correlation is ofte n difficult to obtain during spontaneous syncope because of its sporadic, i nfrequent, and unpredictable nature. Methods and Results-We used a prolonged monitoring strategy to determine th e cause of syncope in 85 patients (age, 59+/-18 years; 44 men) with recurre nt undiagnosed syncope with an implantable loop recorder capable of cardiac monitoring for up to 18 months. During a mean of 10.5+/-4.0 months of foll ow-up, symptoms recurred in 58 patients (68%) 71+/-79 days (2.3+/-2.6 month s) after implantable loop recorder insertion. An arrhythmia was detected in 42% of patients who recorded a rhythm during recurrent symptoms, with brad ycardia present in 18 and tachycardia in 3. Five of the 18 bradycardic pati ents and 2 additional sinus rhythm patients received a clinical diagnosis o f neurally mediated syncope, Patients who experienced presyncope were much less likely to record an arrhythmia during symptoms compared with recurrenc e of syncope (24% versus 70%, P=0.0005), There were no adverse events assoc iated with recurrent symptoms, and there were no sudden deaths. Inability t o freeze after an event occurred in 8 patients, and pocket infection occurr ed in 3, Conclusions-The strategy of prolonged monitoring is effective and safe in p atients with problematic syncope.