Usefulness of tilt test-induced patterns of heart rate and blood pressure using a two-stage protocol with glyceryl trinitrate provocation in patientswith syncope of unknown origin

This study assesses the vasovagal collapse pattern changes, i.e, heart rate (HR) and arterial blood pressure (BP) with a 2-stage tilt-test protocol us ing glyceryl trinitrate (GTN) provocation. With use of the 45-minute 60 deg rees head-up Westminster protocol, 102 consecutive patients were studied. S ublingual GTN 300 mu g was given to those with a negative passive tilt. Hea rt rate and BP patterns were classified according to the Vasovagal Internat ional Study classification (VASIS)and then compared between those with a po sitive passive tilt and those with a positive tilt after having been given GTN. Twelve patients did not. tolerate tilt testing, and 16 herd a negative response despite taking GTN. Thirty-five patients (20 women and 15 men, me an age 45 +/- 21 years [mean +/- SD]) did not take GTN and 38 (26 women and 12 men, mean age 53 +/- 22 years) had positive passive test results. When comparing the VASIS classification between the 2 groups, results showed: ty pe 1, mixed BP and HR decreased without severe bradycardia (31% [passive] v s 54% [with GTN], p = NS); type 2A, BP decreased before HR decreased (20% v s 22%, p = NS); type 2B, HR decreased before or coincident with BP (34% vs 8%, p = 0.003); type 3, BP decreased without HR decrease (9% vs 0%, p = NS) ; exception 1, chronotropic incompetence (0% vs 13%, p = 0.026); and except ion 2, excessive HR increase (6% vs 3%, p = NS). Thus, GTN use increases fr equency of positive results from 34% to 73%. Older people with chronotropic incompetence, who may benefit from pacing, were identified. In younger peo ple there was an increase in those with cardioinhibition. (C) 1999 by Excer pta Medica, Inc.