Paroxysmal AV block and persitance of atrial rhythm during Tilt – table related syncope – any significance?

Introduction: Tilt-table testing (TTT) is an established investigation in patients with vasovagal syncope. Most of the positive TTT with cardioinhibitory response will show atrial and ventricular asystole. There is still a controversy regarding to the interpretation of TTT result if paroxysmal AV block appears or atrial rhythms persist during syncope. Purpose: To evaluate the incidence of persistent supraventricular rhythms and paroxysmal AV block during TTT and to assess their diagnostic and treatment implications. Methods: We enrolled all patients (pts) with history of syncope of unknown origin that have addressed our laboratory over a period of 2 years. Exclusion criteria were: presence of structural heart disease, proven ischemic heart disease and documented malignant ventricular arrhythmias. We performed TTT to enrolled patients using the modified Italian protocol. We considered the result positive if syncope or persistent and severe symptomatic orthostatic hypotension (SBP <50 mm Hg, >2 measurements) were present. Cardioinhibitory response was defined as asystole more than 5 seconds. Results: 160 pts with positive history for syncope (84 F, 76 M, mean age 54,5 ±17) were included in our study. Th e TTT was positive for 113 pts (70.63%) – 43 pts had vasodepressor response, 31 pts cardioinhibitory response and 39 pts a mixed response. During syncope, 34 pts. presented with sinus bradycardia, 25 pts with asystole/pauses > 5 seconds, 14 pts with different perisyncopal supraventricular arrhythmias (junctional/ atrial rhythm, paroxysmal atrial fi brillation), 2 pts with complete heart block, 1 pt with Mobitz 1 AV block and 1 pt with first degree AV block. 4 of these pts underwent permanent pacemaker implantation. There was no spontaneous vasovagal syncope following PM implant in this group. We didn’t record any vagal mediated ventricular arrhythmias in our study group. Conclusions: Most of the patients with cardioinhibitory TTT response will have perisyncopal ventricular and atrial asystole, which doesn’t give us any information regarding A-V conduction. However, a small number of our patients had persistent atrial activity and/or paroxysmal AV block. What should be the proper interpretation and implications of paroxysmal AV block and/or persistent atrial rhythms in patients with cardioinhibitory response during TTT has to be further investigated.

ISSN – online: 2734 – 6382
ISSN-L 1220-658X
ISSN – print: 1220-658X
The Romanian Journal of Cardiology is indexed by:
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CODE: 379
CME Credits: 10 (Romanian College of Physicians)