USE OF SUBLINGUAL GLYCERYL TRINITRATE DURING HEAD-UP TILT AS A PROVOCATIVE TEST FOR VASOVAGAL RESPONSES IN ELDERLY PATIENTS WITH UNEXPLAINED SYNCOPE

Background Head-up tilt, a diagnostic test for vasovagal syncope, is i ncreasingly undertaken in elderly patients with unexplained syncope. T he diagnostic yield of tilt testing may be increased with the concurre nt administration of isoprenaline but this may not be an appropriate p rovocative agent in elderly patients. Glyceryl trinitrate has been sho wn to increase the sensitivity while maintaining the specificity of he ad-up tilt in younger patients. The aim of this study was to compare h aemodynamic responses to head-up tilt after sublingual glyceryl trinit rate with those to tilt alone in elderly patients with recurrent unexp lained syncope and healthy controls. Methods Twenty-one patients (mean age 70 +/- 6 years; 13 female) with recurrent unexplained syncope and 14 healthy controls (69 +/- 7 years; five female) were studied. All s ubjects underwent head-up tilt at 70 degrees for 30 min both before an d after 400 mu g sublingual glyceryl trinitrate. Results Positive resp onses occurred in 24% of patients during head-up tilt and in 67% durin g tilt with nitrate provocation (P < 0.05). No control had a positive response to tilt alone, while tilt with nitrate provocation was positi ve in 14%. No adverse effects occurred during head-up tilt following s ublingual glyceryl trinitrate. The time to symptoms was significantly less during this procedure compared with that observed with head-up ti lt alone (7 +/- 6 versus 17 +/- 5 min; P < 0.01). Conclusion Sublingua l glyceryl trinitrate increases the diagnostic yield obtained during h ead-up tilt in elderly patients with unexplained syncope while maintai ning the specificity and reducing the necessary duration of this test. The procedure is well tolerated in elderly patients.