Background: The aim of this study was to evaluate implantable loop recorders (ILRs) in an unselected cohort in order to determine diagnostic yield, time to pacemaker/implantable cardioverter defibrillator (ICD) implantation, predictors thereof, safety issues, and syncope management including usage of preceding diagnostic tools.

Methods: Patients who underwent ILR evaluation in any of three centers in Region Gävleborg, Sweden, between April 2007 and April 2013 were included and their medical records retrieved. Logistic regression was used to evaluate predictors of pacemaker/ICD outcome expressed as odds ratios (ORs) and Kaplan-Meier estimates for time-dependent analysis.

Results: A total of 173 patients (52.6% females) with a mean age of 56.2 years received an ILR during a mean follow-up of 605 days. In the 146 patients evaluated for syncope/presyncope, 28.1% received a pacemaker (n = 39) or ICD (n = 2). The cumulative incidence at 6, 12, and 18 months were 8.8%, 21.3%, and 26.7%, respectively. Age > 75 years was the only significant predictor for outcome (p = 0.010) and the following variables showed a tendency toward significance: abnormal elevation of the biomarker brain natriuretic peptide (OR 2.05, p = 0.100), a history of trauma (OR 1.71, p = 0.179), and pathologic ECG (OR 1.68, p = 0.231). A computerized tomography of the skull was performed in 52.1% of the syncope cases.

Conclusions: In syncope evaluation in an unselected cohort, 28.1% were diagnosed with an arrhythmia necessitating a pacemaker/ICD. The only significant predictor was advanced age. Time to diagnosis is unpredictable and prolonged ILR monitoring is warranted in addition to optimal use of other diagnostic tools.