3. Results
A flow diagram of patient enrollment is shown in Figure 1. Sensitivity and specificity were calculated based on 57 patients with a Calgary Score ≥ - 2. All patients participated in the first HUTT, and 34 patients experienced syncope or presyncope (3 in BHUT and 31 in NHUT). The 39 patients with a negative HUTT received a TET, and 14 experienced syncope or presyncope. The 25 patients with a negative TET received a second HUTT, and 9 patients experienced syncope or presyncope (2 in BHUT and 7 in NHUT). Thus, the sensitivity and specificity of the first HUTT was 56.1% (32/57) and 87.5% (14/16), respectively. The sensitivity of the first HUTT combined with the TET increased to 78.9% (45/57), without a change in the specificity of 87.5% (14/16). Finally, the combination of the first HUTT, TET, and the second HUTT demonstrated a sensitivity of 94.7% (54/57), and a specificity of 81.3% (13/16).
The mean age of patients who had a positive response in the first HUTT was 48.1 ±5.6 years, and 52.9% of them were male. Compared with patients who had a negative response in the first HUTT, patients with a positive response were older, had a greater number of episodes, were more likely to develop syncope during urination or changing position, and a greater number experienced loss of consciousness. However, more patients who have negative response induced by extensive exercise and suffered from abdominal pain, facially pallor and sweating in the syncope attack. Other baseline characteristics were not significantly different between the 2 groups (p > 0.05).
Compared to patients with a negative response in the HUTT combined with the TET, patients with positive response had a longer history of syncope, were more likely to have an episode with standing for a long time or walking, and were more likely to experience sweating and facial pallor. Other characteristics and symptoms were not different between the 2 groups (p > 0.05). Patient characteristics are summarized in Table 1.
The characteristics of TET positive and negative patients are shown in Table 2. The 14 patients who had a positive TET had the following symptoms at recovery: fatigue, dizziness, sweating, graying of vision, and fatigue at recovery. Compared to patients with a negative TET, those with a positive TET had a greater maximal predictive heart rate, maximal heart rate, percent of maximal predictive heart rate, and exercise tolerance. Other exercise data were not different between positive and negative TET patients. However, the mean age of the positive patients was less than that of the negative patients. In addition, the systolic and diastolic blood pressure in the recovery phase were greater in positive patients than in negative patients. Of the patients with a positive TET, 5 became unconscious, 4 exhibited nausea, and one patient experienced vomiting. Presyncope or syncope occurred between 0:40 and 5:23 min during recovery, with duration of 2 to 10 min. The most common hemodynamic pattern was cardio-inhibitory type (VASIS II, 42.9%, 6 patients). During recovery, the onset of bradycardia was without hypotension in 6 patients, and the heart rate decreased more than 55 bpm (mean 78 ± 11.5 bpm). In 2 patients, the electrocardiogram showed sinus arrest and an escape rhythm (1 atrial escape rhythm and 1 junctional escape rhythm). Four patients had a mixed response (VASIS I, 35.7%). Their heart rate dropped to 50 bpm, and in 1 patient the electrocardiogram showed a junctional escape rhythm. Three patients had a vasodepressor type response (VASIS III, 21.4%). Their blood pressure (especially systolic pressure) decreased to < 1/3 of the average blood pressure after exercising.
Nine patients who received a second HUTT after a negative TET had a positive result (2 in BHUT and 7 in NHUT). In all 9 patient symptoms were relieved when they were returned to the supine position, and heart rate and blood pressure became normal within 10 min after lying down. The maximal heart rate, the percentage of maximal predictive heart rate, and exercise tolerance were all higher in the positive group than in the negative group. Patients who had a positive second HUTT had a longer history of syncope, were more likely to have an episode with standing for a long time or walking, and were more likely to experience sweating and facial pallor. These results indicate that the combination of TET and HUTT detected patients with adrenergic excitation, and exhibited more symptoms of sympathetic excitation.