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.