p.24 抽出テキスト

..................................................................................................................................................... the investigation of palpitations,163 they have a marginal role in the evaluation of syncope.

4.2.4.4 Smartphone applications Because up to now smartphone applications have recorded real-time ECG, their current role in syncope is limited for the same reason as for prospective event recorders.164,165 However, home video records are very useful in all forms of TLOC (see section 4.2.5.2).

4.2.4.5 External loop recorders In general, external loop recorders have a higher diagnostic yield than Holter monitoring.162 External loop recorders can be useful in patients with relatively frequent syncope episodes.166–168 In a recent multicentre international registry, the diagnostic yield in syncope was 24.5%, with the most common finding being bradyarrhythmias; the stronger predictor for diagnostic findings was early monitoring after the index event.166

4.2.4.6 Remote (at home) telemetry Most recently, external and implantable device systems have been developed that provide continuous ECG recording or 24-h loop memory with wireless transmission (real time) to a service centre. Some recent studies have shown that implementing remote monitoring increases the diagnostic yield and achieves diagnosis earlier than without remote monitoring.169–171

4.2.4.7 Implantable loop recorders In a meta-analysis of five randomized controlled trials (RCTs),172–176 660 patients with unexplained syncope were randomized to a conventional strategy consisting of an external loop recorder, tilt testing, and an electrophysiological study (EPS), or to prolonged monitoring with an ILR. The results showed that initial implantation of an ILR in the workup provided a 3.7 [95% confidence interval (CI) 2.7–5.0] increased relative probability of a diagnosis compared with the conventional strategy (see Supplementary Data Table 5). ILR was more cost-effective than a conventional strategy.172,173,177,178 In pooled data from nine studies179 performed in 506 patients with unexplained syncope at the end of complete negative work-up, a correlation between syncope and ECG was found in 176 patients (35%); of these, 56% had asystole (or bradycardia in a few cases) at the time of the recorded event, 11% had tachycardia, and 33% had no arrhythmia. Presyncope was much less likely to be associated with an arrhythmia than syncope. Similar findings were subsequently observed with ILR use expanded in an early phase of evaluation in patients with recurrent syncope of uncertain origin, in the absence of highrisk criteria and structural heart disease,176,180–183 and in suspected reflex syncope.184–186 In particular, an asystolic pause was present during syncope in about 50% of these patients. There are several areas of interest other than unexplained syncope in which ILRs have been investigated:

• Patients with bundle branch block (BBB) in whom paroxysmal atrioventricular (AV) block is likely despite negative complete EPS: an arrhythmia was observed in 41% of these patients (being paroxysmal AV block in 70%) under ILR observation, based on pooled data from three studies174,187,188 (see Supplementary Data Table 6). • Patients in whom epilepsy was suspected but the treatment has proven ineffective: in pooled data, an attack could have been documented by ILR in 62% of patients, with an arrhythmic cause being responsible in 26%137,189–191 (see Supplementary Data Table 7). • Patients with unexplained falls: in pooled data, an attack could have been documented by ILR in 70% of patients, with an arrhythmic cause being responsible in 14%191–194 (see Supplementary Data Table 8). • Patients with HCM, arrhythmogenic right ventricular cardiomyopathy (ARVC), or primary electrical diseases (see section 5.4).

4.2.4.8 Diagnostic criteria The gold standard for the diagnosis of arrhythmic syncope is when there is a correlation between the symptoms and an ECG recording.195,196 The presence of asymptomatic significant arrhythmias— defined as prolonged asystole (>_3 s), rapid supraventricular tachycardias (SVTs) (i.e. >160 b.p.m. for >32 beats), or ventricular tachycardias (VTs)—has been considered by several authors to be a diagnostic finding.185,188,197–199 On the other hand, although the absence of documentation of an arrhythmia during a syncopal episode cannot be considered to be a specific diagnosis, it allows the exclusion of an arrhythmia as the mechanism of the syncope. Most evidence in support of the above diagnostic criteria is indirectly based on the benefit of specific therapies guided by ECG monitoring in preventing syncopal recurrences.172,184–186,188,200 Even if the quality of evidence is moderate, there is strong consensus based on evidence from several controlled trials that a correlation between symptoms and a documented arrhythmia, or the presence of some asymptomatic significant arrhythmias (defined above), is diagnostic of the cause of syncope and specific treatment must be prescribed. The principal limitation of any ECG monitoring device is the inability to record BP together with ECG. In reflex syncope, the documentation of bradycardia/asystole during a syncopal episode does not rule out the possibility that a hidden hypotensive reflex is the principal cause for syncope, and that bradycardia/asystole is a secondary late event. This issue has important implications for therapy (see section 5). A classification of ECG recordings with their probable related pathophysiology is available in Web Table 6 and Web Practical Instructions section 8. Downloaded from academic.oup.com/eurheartj/article/39/21/1883/4939241 by guest on 07 October 2026