Syncope is a common presenting condition. Pacemaker implantation can significantly reduce syncope recurrences in reflex syncope. However, despite careful selection, a substantial proportion of patients treated with pacemakers suffer recurrences of syncope. It is thought that a pronounced vasodepressor component may hinder the efficacy of pacing in patients, preventing adequate cerebral perfusion during the reflex, thus relativizing the anti-bradycardia function of the pacemaker to prevent syncope. It is hypothesised that the time elapsed from the actual loss of consciousness to the asystole recorded on the ECG during Tilt Table Test may be predictive in terms of response to pacemaker therapy, so this parameter becomes the subject of the present study.

Syncope is a common leading affection and is responsible for 1-3% of the presentations in emergency departments and up to 3% of inpatient admissions. Syncope poses often a diagnostic and therapeutic challenge for the attending physician and is often misdiagnosed or underdiagnosed. Patients can be treated with pacemaker implantation when the syncope cause is a cardioinhibition with documented asystole during the syncopal event. When accurately selected, patients benefit from pacemaker therapy with a significant reduction of syncope recurrence in the follow up. However, a substantial portion of the patients (approx. 25%) experience recurrence of syncope despite optimal pacemaker therapy. The underlying mechanism is not well understood and object of the current study.

The main target of the study is to evaluate the time elapsed between the T-LOC during Video Tilt Table Testing and the asystole at the ECG using a registry and to assess its predictive value in patients undergoing invasive treatment. The hypothesis is that a vasodepressive component could lessen the effect of pacing in a patient, leading to cerebral hypoperfusion and syncope despite maintaining a stable rhythm.

This is a prospective, multi-center observational study with 2 year follow-up of patients. Patients eligible for invasive treatment of reflex syncope are included.

If after guideline-directed implantable loop recorder insertion no cardioinhibition has been recorded, the patient is included automatically in the registry.

Inclusion Criteria:

• Patients eligible for invasive treatment according to the ESC Guidelines for pacing 2021
• Written informed consent

Exclusion Criteria:

• Other condition which explains syncope cause other than reflex syncope
• Structural heart disease (valvular, ischaemic, cardiomyopathies)
• Pregnancy
• Patient denial to be recorded on video during tilt table test

Patients affected by neurally mediated syncope eligible for invasive treatment according to the ESC Guidelines for pacing 2021