The usefulness of tilt testing with an intravenous beta-blocker in assessing the efficacy of long-term therapy in patients with vasovagal syncope.

BACKGROUND

Although beta blockers are frequently used for the prevention of recurrences of vaso-vagal syncope, the prediction of the long-term efficacy of this treatment is difficult.

AIM

To assess whether the result of tilt testing with an intravenous beta blocker can predict the long-term efficacy of beta blockade.

METHODS

The study group consisted of 62 patients (29 females, mean age 32.8+/-12.3 years and 33 males, mean age 35.9+/-18.2 years) with at least two syncopal episodes during the six months preceding positive tilt testing. After baseline tilt test, propranolol in a dose of 0.1 mg/kg body weight was administered intravenously and the tilt test was repeated. Beta blockade was defined effective if the second tilt test was negative (complete efficacy) or the time to syncope during tilt testing was increased compared with the baseline tilting (partial efficacy). All patients received chronic propranolol treatment and were followed for one year or till the recurrence of syncope.

RESULTS

Intravenous propranolol prevented (n=33) or delayed (n=18) syncope during tilt testing in 51 (82%) patients whereas it was ineffective in the remaining 11 (18%) patients. During 8.6+/-6.7 (range 1-14) months of follow-up, 20 (32%) patients had syncope recurrence; 13 (25%) from the group with effective intravenous propranolol versus 7 (64%) patients in whom intravenous propranolol did not prevent syncope during tilt testing (p<0.015). Analysis of survival without a recurrence of syncope revealed a significant relationship between the results of tilt testing with intravenous propranolol and the efficacy of long-term beta-blocker therapy (p<0.003). There were no significant differences between the predictive value of tilt testing with propranolol between patients with complete or partial propranolol efficacy (NS) whereas significant differences between each of these two groups and patients with ineffective intravenous propranolol were noted (p<0.04 and p<0.002, respectively).

CONCLUSIONS

Propranolol administered intravenously prevents syncope during tilt testing in a significant proportion of patients. Both complete or partial efficacy of intravenous propranolol predict long-term efficacy of chronic beta blocker therapy in patients with vaso-vagal syncope.