Background: The use of tilt testing (TT) in guiding therapy in patients with syncope remains controversial.
Aim: To assess the long-term effectiveness of TT-based therapy in patients with syncope of unknown origin.
Methods: The study group consisted of 340 patients (182 females, mean age 38.2+/-16.5 years, range 15-78 years) with at least two syncopal episodes during 6 months preceding the study. TT was performed at 60 degrees angle for 20 min, followed by sublingual nitroglycerine (NTG) challenge (250 microg) when necessary. After positive baseline TT and returning to supine position, 0.1 mg/kg of propranolol was intravenously administered and a second TT was performed. All patients with positive TT were advised to take propranolol, midodrine or fludrocortisone for 6 months -- the choice of agent was based on standard criteria. The time to first syncope was an indicator of the efficacy of treatment and a recurrence of syncope was the end-point of the study. In patients who did not faint during follow-up, the last date of contact was taken as the end of observation period.
Results: Out of 340 patients who underwent TT, 148 with positive TT and propranolol challenge were included in the study; 82 patients (group I) received long-term therapy whereas 66 did not (group II). During a 12.8+/-0.9 month follow-up, syncope recurred in 86 patients - 40 (49%) from group I and 46 (70%) from group II (p<0.01). Survival analysis showed that medical therapy was associated with a significant reduction of the risk of syncope recurrence (RRR: 36%, 95% CI: 23-47). The greatest benefit from long-term treatment was documented in patients taking propranolol (RRR: 42%; 95% CI: 18-58; p<0.008), particularly in those in whom intravenous propranolol prevented TT-induced syncope (RRR: 50%; 95% CI: 23-67; p<0.012). Risk reduction in patients treated with midodrine or fludrocortisone was moderate (RRR: 22%; 95% CI: 11-34; p>0.09).
Conclusions: Carefully selected and TT-based long-term pharmacological treatment is associated with a 36% risk reduction of syncope recurrences in patients with syncope of unknown origin.