Effect of Food Intake on Hemodynamic Parameters during the Tilt-Table Test in Patients with Postural Orthostatic Tachycardia Syndrome.

Background And Purpose: The aim of this study was to determine the effect of food intake on the heart rate (HR) in postural orthostatic tachycardia syndrome (POTS).

Methods: The following five-phase protocol was applied to 41 subjects who had a sustained HR increment of ≥30 beats/min within 10 min of standing in an initial tilt-table test: 1) 10-min supine phase, 2) 10-min 70°-tilted phase, 3) ingestion of 400 mL of Nutridrink Multi Fibre®, 4) 45-min supine phase, and 5) 10-min 70°-tilted phase. Subjects were divided into four groups: A) difference in HR for standing vs. supine (ΔHR) before the meal of ≥30 beats/min (=13), B) ΔHR <30 beats/min before the meal but ≥30 beats/min after the meal (=12), and C) ΔHR <30 beats/min both before and after the meal (=16). Group D consisted of 10 healthy subjects.

Results: Before the meal, ΔHR was significantly higher in group A than in all of the other groups, and in group B than in group D (<0.001). After the meal, ΔHR was significantly higher in groups A and B (<0.001 and <0.0001, respectively). When we pooled patients (according to their symptoms) from group A and B into a POTS group and from group C and D into a non-POTS group, an increase in HR of 25 beats/min before the meal had a sensitivity of 92.0% and a specificity of 80.8%. After the meal, an increase in HR of 30 beats/min had a sensitivity of 96.0% and a specificity of 96.2%.

Conclusions: Food intake can significantly alter the results of the tilt-table test and so should be taken into account when diagnosing POTS.