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Comparison of sensitivity and specificity of tilt protocols with and without isoproterenol in children with
1Department of Pediatrics, Hacettepe University Faculty of Medicine, Ankara, Turkey.
Insights
Head-up tilt testing is crucial for diagnosing unexplained syncope in children. Adding isoproterenol increases test sensitivity for syncope diagnosis without reducing specificity.
Area of Science:
- Pediatric Cardiology
- Autonomic Nervous System Function Testing
- Diagnostic Accuracy Studies
Background:
- Unexplained syncope is a common clinical problem in children.
- Head-up tilt testing (HUTT) is a standard diagnostic tool for syncope.
- The diagnostic utility of HUTT with and without isoproterenol in pediatric populations requires further clarification due to limited age-matched control data.
Purpose of the Study:
- To assess and compare the sensitivity and specificity of HUTT alone versus HUTT with isoproterenol in children with unexplained syncope.
- To evaluate the impact of graded isoproterenol infusion on the diagnostic yield of HUTT.
- To establish optimal protocols for pediatric syncope workup.
Main Methods:
- Two groups of children with unexplained syncope and age-matched controls were studied.
- Group I underwent HUTT with graded isoproterenol infusions (0.02–0.06 µg/kg/min).
- Group II underwent HUTT without isoproterenol infusion.
Main Results:
- HUTT with isoproterenol demonstrated a sensitivity of 76.6% and specificity of 86.7% in Group I.
- HUTT without isoproterenol showed a sensitivity of 48.5% and specificity of 93.4% in Group II.
- Significant decreases in heart rate and blood pressure were observed in all tilt-positive patients during syncope.
Conclusions:
- Head-up tilt testing is a valuable diagnostic tool for evaluating unexplained syncope in children.
- Isoproterenol augmentation of HUTT appears to enhance sensitivity for diagnosing syncope in pediatric patients.
- The addition of isoproterenol to HUTT does not compromise test specificity in this pediatric cohort.
Abstract:
Head-up tilt testing with or without isoproterenol is extensively used in the evaluation of patients with unexplained syncope. However, sensitivity and specificity of tilt protocols with and without isoproterenol have not been clarified in children, due to lack of age matched control subjects. This study was designed to assess and to compare the sensitivity and specificity of tilting alone and tilting in conjunction with isoproterenol. Thirty children with unexplained syncope (group I) and 15 age-matched control subjects (control group I) underwent successive 60 degrees head-up tilts for 10 minutes during infusions of 0.02, 0.04, and 0.06 microgram/kg/min of isoproterenol, after a baseline tilt to 60 degrees for 25 minutes. Also, 35 children (group II) with unexplained syncope and 15 healthy control subjects (control group II) were evaluated by head-up tilt to 60 degrees for 45 minutes without an infusion of isoproterenol. In response to tilt protocol with graded isoproterenol, 23 (76.6%) of the patients in group I and 2 of the 15 (13.3%) control subjects developed syncope. Accordingly, the sensitivity of tilt testing with isoproterenol was 76.6%, and its specificity was 86.7%. Tilt testing without isoproterenol was positive in 17 (48.5%) of the patients in group II but in only 1 of the 15 (6.6%) control subjects. Thus, sensitivity and specificity of tilt testing without isoproterenol were 48.5% and 93.4%, respectively. The mean heart rate and systolic blood pressure decreased significantly (P < 0.001) in all tilt positive patients during syncope. In conclusion, the head-up tilt test is a valuable diagnostic test in the evaluation of children with unexplained syncope, and isoproterenol is likely to increase the sensitivity of the test without decreasing its specificity.