Implantable loop recorder for recurrent syncope: influence of cardiac conduction abnormalities showing up on resting electrocardiogram and of underlying cardiac disease on follow-up developments

Aims The implantable loop recorder is a useful diagnostic tool in dealing with recurrent syncope in patients. We tested to determine the influence of cardiac conduction abnormalities that turn up on resting electrocardiogram (ECG) and the impact of underlying cardiac disease on developments during follow-up. Methods and results Ninety-five consecutive patients received an implantable loop recorder to monitor recurrent syncope ( n = 4.9±3.8) of unknown aetiology after cardiac investigations, including an electrophysiological study. Resting ECG was abnormal, suggesting an arrhythmic syncope, in 29 (30.5%) patients, while 21 (22.1%) patients had an underlying cardiac disease. During an average follow-up period of 10.2±5.2 months, 43 (45.2%) patients developed a new syncope associated in 27 of them (62.8%) with an arrhythmic event. Syncope was no more frequent in the subgroup of patients with cardiac conduction abnormalities on resting ECG, while the frequency of arrhythmic events was similar whether or not the ECG was normal. In the subgroup of patients with cardiac disease with normal left ventricular ejection fraction, the occurrence of syncope was less frequent, and the number of arrhythmic events was no greater in these patients. Conclusion Implantable loop recorder is a useful diagnostic tool for recurrent syncope of unknown aetiology.