Tilt table evaluation for control pediatric patients: Comparison with symptomatic patients

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Abstract
This study was designed to evaluate pediatric control patients during head‐up tilt in comparison with symptomatic neurocardiogenic syncope patient head‐up tilt responses. Twenty‐three pediatric control (c) patients (13 females, 10 males; 11.9 ± 3.1 years) were tested with head‐up tilt (HUT) and compared with 66 symptomatic (s) patients. Baseline drug‐free HUT (cHUT‐1), a second drug‐free HUT (cHUT‐2), and a final HUT with isoproterenol infusion (cHUT‐3) were each performed at 80° tilt angle for 30 min or until positive. For comparison, 66 symptomatic patients (41 females, 25 males; 13.6 ± 2.5 years) underwent drug‐free HUT (sHUT‐1); negative responders during sHUT‐1 underwent follow‐up HUT with isoproterenol (sHUT‐2). HUT data were compared for both groups at both 30 and 20 min tilt duration. Twelve control patients (52%) had a symptomatic response during cHUT‐1 at 18±8 min. During cHUT‐2, 5 of 23 patients were positive at 13±5 min; each had previously tested positive during cHUT‐1. Two patients, each positive in cHUT‐1 and cHUT‐2, refused cHUT‐3. The only patient testing positive during cHUT‐3 was test positive in cHUT‐1 but negative for cHUT‐2. In comparison, 43 of 66 (65%) symptomatic patients tested positive during drug‐free sHUT‐1 at 11±6 min. Subsequently, 20 of the 23 negative patients underwent HUT with isoproterenol (sHUT‐2), with 8 of 20 testing positive. Thus, 51 of 66 symptomatic patients (77%) were called “true positives.” Chi‐square analysis for comparison of 30 min cHUT‐1 (12/23 positive patients) versus sHUT‐1 (43/66 positive patients) yielded no statistical difference. However, analysis of data limited to 20 min tilt duration showed 7 of 23 positive cHUT‐1 versus 38 of 66 positive sHUT‐1 patient responses (p = 0.025). It is concluded that (1) pediatric HUT is relatively nonspecific in a control population (52% false positive), (2) concordance for consecutive positive control tilts is low, (3) isoproterenol does not increase overall predisposition to positive pediatric control patient response, and (4) an 80° tilt protocol limited to 20 min duration may help differentiate between false and true positive responses.