Introduction: implantable loop recorders permitted to clarify the syncope aetiology with negative when basic exams are inconclusive. They are especially useful when the cause of syncope is related to transitory bradycardia or sinus arrest with sporadic symptoms. The authors aimed to evaluate the influence of cardiovascular risk factors and previous electrocardiogram (ECG) conduction disturbances in indication to implant definitive pacemaker in patients with syncope and dizziness who implanted an ILR.
Methods: we evaluated 63 patients with an ILR implanted between 2002 and 2012. The mean age was 62.3 years old and 22% were diabetic, 59% had hypertension, 2% were current smokers and 41% had elevated blood lipids. The ECG previous to ILR, presented with first degree auricular-ventricular block in 13.2% of patients, complete left bundle branch block in 7.3%, right bundle branch block in 5.5% and left anterior fascicular block in 9.1%.
Results: ILR allowed the diagnosis of the aetiology of syncope in one third of patients, and the causes identified were sinus node dysfunction (70%), complete AVB (20%) and supraventricular tachycardia, including atrial fibrillation (10%). It also permitted to exclude dysrithmic events as cause of syncope in 33% of patients, as event reorder was activated and no ECG disturbance was found. A pacemaker was implanted in 30% of patients, about 20 months after ILR. Of the patients who needed pacing, 42% were diabetic and we also found that more than half of the diabetic patients needed a pacemaker according to current guidelines (p<0.05).No relationship was found with other risk factors. Curiously, previous conduction disturbances did not predict the indication to pacemaker placement, as one expected
Conclusions: with this study we realized the relevance of ILR use, allowing us to diagnose disrítmica events in 30% of patients and excluding this diagnosis in another 32%. It also alerted us to the need of a low threshold when suspecting sinus node disease. We also concluded that diabetes predicts better the indication to pacemaker placement than previous conduction disturbances in these selected patients. This could be explained by the dysautonomic dysfunction often seen in diabetics.