A FIVE-MINUTE TILT TABLE TEST AS PART OF DIAGNOSTIC ALGORITHM OF SYNCOPE
The purpose of the study - establishing of the diagnostic model based on results of Tilt Table Test (TTT) using changes of parameters in hemodynamics of cardiovascular system during early period of orthostatic changes to improve testing algorithm for patients with syncope. Materials and methods: We included 212 patients with history of vasovagal syncope (72.6% males, median age 41). During preliminary evaluation we ruled out other reasons for syncope. All patients had TTT using standard protocol developed at Institute of Clinical Cardiology (Moscow, Russia) that includes monitoring of parameters of hemodynamics using method of impedance cardiography, as well as spectral analysis of cardiac rhythm and changes in arterial blood pressure taken using Korotkoff's technique. Results: Based on results of TTT all patients were divided in two groups: with vasovagal syncope during the test - TTT(+) (n=110) and without syncope - TTT(-) (n=102). Based on comparison of hemodynamic parameters during first 5 minutes of TTT between 2 groups, using method of logistic regression we developed this formula: Y=3.8 MAP+(%MPVR)+14(%EIC)+(%LFN), where MAP - mean arterial blood pressure; %MPVR - % change of peripheral vascular resistance; %EIC - change of basal electric impedance chest area; %LFN - change of the normalized power of low frequency of rhythmogram. First 3 parameters are taken at the end of 1 st minute of orthostasis, and the 4 th parameter - at the end of 5 th minute. Percent of change of the 2-4 parameters are calculated relative to their initial values with patient in supine position. Based on ROC analysis Y=500 devided patients with syncope and without syncope with sensitivity of 74.5% and specificity of 82.4%. Thus, calculation of the above parameters during 5 minute TTT allows us to determine prognostic results of TTT in patients with vasovagal syncope.