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.............................. 4.5 Electrophysiology study The development of non-invasive ambulatory ECG technologies has reduced the need for the electrophysiology study (EPS) as a diagnostic test. EPS is generally an adjunctive tool in the evaluation of patients with syncope in whom bradycardia is suspected but has not been documented after non-invasive evaluation (Figure 4). The goal of an EPS in the context of bradycardia evaluation is to identify abnormal sinus node function or the anatomical location of the cardiac conduction disorders (in the AVN or in the HisPurkinje system distal to the AVN). In patients with syncope and sinus bradycardia, the pre-test probability of bradycardia-related syncope increases when there is a sinus bradycardia (<50 b.p.m.) or sinoatrial block. Observational studies have shown a relationship between prolonged sinus node recovery time with syncope and the effect of pacing on symptoms.113,114

In patients with syncope and bifascicular block, a prolonged Hisventricular interval (HV) >_70 ms, or HV >_100 ms after pharmacological stress (ajmaline, procainamide, flecainide, or disopyramide), or induction of second- or third-degree AVB by atrial pacing or by

History, physical examination, 12-lead ECG and cardiac imaging

Patient with symptoms suggestive of bradycardia or conduction system disease

Early onset of progressive cardiac conduction disease or family history inherited cardiac

conduction disorder Clinical suspicion for potential

causes of bradycardia Syncope and

bifascicular

block

Suspected scar or infiltrative cardiomyopathy Suspected

recurrent reflex syncope

Bradycardia or cardiac conduction disorders during sleep Exercise

induced symptoms

Genetic

test Laboratory

test EPS or ET for

exercisedinduced block or empirical pacemaker in elderly and frail patients

Further imaging (CMR,CT, PET etc.) CSM/ tilt

test Polysomnography

/sleep study ET

Diagnostic

N Y

SND (See section 5.1)

CCD without AV block (See section 5.3) AV block (See section 5.2)

Reflex syncope (See section 5.4) Symptoms

<1 per month

AECG monitoring ILR

Nondiagnostic Clinical follow-up

(non-diagnostic)

Figure 4 Evaluation of bradycardia and conduction disease algorithm. AECG = ambulatory electrocardiographic monitoring; AV = atrioventricular; CCD = cardiac conduction disease (or disorder); CMR = cardiovascular magnetic resonance; CSM = carotid sinus massage; CT = computed tomography; ECG = electrocardiogram; EPS = electrophysiology study; ET = exercise test; ILR = implantable loop recorder; PET = positron emission tomography; SND = sinus node dysfunction. Downloaded from academic.oup.com/eurheartj/article/42/35/3427/6358547 by guest on 07 October 2026