The Evaluation of Heart Rate Variability in Patients with Postural Tachycardia Syndrome

Abstract

Purpose: Postural tachycardia syndrome (POTS) is a disease associated with dysautonomia. Disruption of the sympathetic/parasympathetic balance is the main pathophysiological mechanism. The aim of this study was to evaluate this imbalance with mean heart rate and spectral parameters of heart rate variability measured by ambulatory rhythm monitoring. Patients and methods: One hundred and ninety-three patients with negative HUT test results and without any chronic disease enrolled in the study between 2014 and 2018. POTS was diagnosed when a 30 beats per minute increase at heart rate compared to baseline was observed during the first 10 minutes of the 70 ͦ tilt test. Patients were divided into two groups as POTS (n=27) and non POTS (n=166). Results: POTS was diagnosed in 27 (%13.9) of the 193 patients with negative HUT. Spectral parameters of heart rate variability as SDNN, SDANN, rMSSD and pNN50 values were similar between groups. Average heart rate was significantly higher in POTS patients when compared with non-POTS patients (%80 vs%47.8, p=0.024). Average heart rate above 75 beats per minutes was the only independent predictor for POTS [OR: 4.608 (1.447-14.705), p=0.01]. Conclusion: Evaluation of average heart rate by 24-hour ambulatory rhythm monitoring may be an important parameter in individuals with POTS without structural heart or chronic disease.