Tilt testing results are influenced by tilt protocol

Abstract

Aims: It is unknown how the return to supine position influences duration of loss of consciousness (LOC) and cardioinhibition during tilt test.

Methods and results: Retrospective analysis of two datasets containing records of patients who underwent tilt testing for unexplained syncope in two centres was performed. Patients, totalling 1232, were included in the study: 262 in a Swedish centre and 970 patients in a Polish centre. In Sweden, tilt table with tilt-down time (TDT) of 18 s was used (Group II). In Poland, two different tilt tables were used, one of them with TDT of 10 s (Group I, n = 325), and the other with TDT of 47 s (Group III, n = 645). Cardioinhibitory reflex occurred most frequently in Group III, whereas number of pauses >3 s, frequency of very long asystole ≥30 s, and the total duration of pauses >3 s demonstrated a trend to increase from Group I to III. Duration of LOC in Groups II and III was significantly longer compared with Group I (32.0 and 33.7 s vs. 16.4 s). In the multivariate-adjusted regression model, cardioinhibitory reflex was predicted by tilt-table model (odds ratio per model with increasing TDT: 1.40; 95% confidence interval, 1.19-1.64; P < 0.0001), whereas LOC duration was longer with increasing TDT (P < 0.0001) and age (P < 0.0001).

Conclusion: Longer TDT during induced vasovagal syncope increases the prevalence of cardioinhibitory reflex and prolongs the duration of LOC. Tilt-down time does not affect asystolic pause duration but delay may lead to occurrence of multiple pauses, higher frequency of very long asystole, and longer total asystole duration.

Keywords: Cardiac arrest; Sudden cardiac death; Syncope; Tilt-table test; Unconsciousness; Vasovagal reflex.