Importance of arterial distensibility in patients with vasovagal syncope

Vasovagal syncope (VS) has a significant place in the etiology of syncope; tilt table (TT) test is used for identification of patients with vasovagal syncope (VS); however, the repeatability of the TT test is low. Upon repeated administration of TT test to patients with a positive result, the test may reveal a negative result. This feature of the test renders it inadequate particularly in evaluating therapeutical efficacy in patients receiving treatment. The left ventricular (LV) volume changes are important in the pathology of VS; in addition, LV volume changes are directly affected by the changes in the arterial system and therefore, the present study investigated arterial distensibility (AD) in this patient population.

A total of 142 VS patients with a positive TT test result (A group) and 93 healthy individuals (B group) were enrolled in the study. The patients received tilt training treatment for 6 months. VS patients were further classified into two: syncope (+) or syncope (-) subgroup according to having at least one or more syncope episode during the 6 months of training program. All patients and controls underwent Doppler echocardiography and AD measurement which were repeated at the end of 6th month in syncope (+) and (-) subgroups.

The mean AD value of patients in group A was significantly lower than that of participants in group B (0.39 ± 0.1 vs. 0.42 ± 0.1, p = 0.025). In Group A, AD was significantly correlated with left ventricular diastolic filling time (DFT), isovolumetric relaxation time and right ventricular DFT (r = 0.38, p < 0.05; r = -0.42, p < 0.05; r = 0.35, p < 0.05, respectively). Syncope (+) subgroup had lower mean AD value compared to syncope (-) subgroup (0.38 ± 0.1 vs. 0.44 ± 0.1, p < 0.001).

AD may have valuable contribution to understanding the pathophysiology underlying VS and AD may be used in evaluating therapeutical efficacy for vasovagal syncope.