Research Article
The complexity of diagnosing postural orthostatic tachycardia syndrome: influence of the diurnal variability

https://doi.org/10.1016/j.jash.2016.01.011Get rights and content

Highlights

  • We evaluated how the diagnosis can be missed in a single orthostatic stress test.

  • Orthostatic tachycardia is more prominent in the morning, but not always.

  • Symptoms were more frequent in the morning, but not during most tests.

  • Orthostatic hypotension can be accompanied in postural orthostatic tachycardia syndrome.

  • We suggest repeated orthostatic stress tests in clinically suspected postural orthostatic tachycardia syndrome patients.

Abstract

We investigated how the diagnosis of postural orthostatic tachycardia syndrome (POTS) would be changed due to diurnal variability in orthostatic tachycardia. The orthostatic vital sign test was administered to each patient twice, in the afternoon of the day of admission and the next morning (n = 113). Forty-six patients were diagnosed with POTS, and the remaining 67 patients were assigned to non-POTS group. Heart rate increments after standing were larger in the morning than in the afternoon in every group (all P < .001). Among the POTS patients, 82.6% fulfilled the diagnostic criteria for POTS in the morning and 52.2% in the afternoon. Most POTS group (65.2%) displayed normal result on single orthostatic vital sign test. Orthostatic intolerance symptoms were provoked in only 45.7% of the POTS patients, more frequently in the morning. In conclusion, diurnal variability in hemodynamic parameters and provoked symptoms significantly challenged the diagnosis of POTS.

Introduction

Postural orthostatic tachycardia syndrome (POTS) is a common cause of orthostatic intolerance which is characterized by an excessive heart rate (HR) increase after standing.1, 2 It predominantly affects young people and is more prevalent in women.3 The clinical significance of POTS is increasingly being appreciated; it has recently been reported that POTS is often accompanied by many comorbidities, including depression, sleep problems, and chronic fatigue syndrome.4, 5, 6, 7, 8, 9 It is important not to miss diagnoses of POTS because it is largely a treatable disease.1, 3, 10

The core diagnostic criteria for POTS consist of an HR increment of ≥30 beats/min (bpm) (or ≥40 bpm in individuals aged 12 to 19 years) within 10 minutes of standing or head-up tilt in the absence of orthostatic hypotension (OH).11, 12, 13, 14 Some studies include a requirement for the appearance of provoked symptoms during orthostatic stress tests15, 16 or a history of chronic orthostatic intolerance17 in the diagnostic criteria for POTS, but these are not universally accepted.

Recently, Brewster et al. have suggested that the diurnal variability of orthostatic tachycardia (OT) affects the diagnosis of the POTS.18 They demonstrated greater OT on the modified (5 minutes) standing test performed in the morning than that in the evening, which resulted in increased diagnosis of POTS in the morning. However, they have not evaluated how many false-negative cases can occur with a single standing test. In the present study, we aimed to reevaluate the influence of HR diurnal variability on the diagnosis of POTS using the standard (10 minutes) orthostatic vital sign (OVS) test and focused on how the diagnosis of POTS can be missed in individual cases according to the timing of the OVS test. We also intended to evaluate the diurnal variability of the provoked symptoms during the OVS test.

Section snippets

Subjects

The electronic medical records of patients who were admitted to the Center for Epilepsy and Autonomic Disorders of Seoul National University Hospital between January 2014 and June 2014 were reviewed (n = 188). The main causes of admission were recurrent orthostatic dizziness, headaches, loss of consciousness, convulsive movements, or other paroxysmal symptoms requiring the exclusion of syncope or seizure disorders for the accurate diagnosis. Patients who underwent two OVS tests, on the

Characteristics of Patients With or Without POTS

A total of 113 patients were included in the study (male: 55; mean age: 41.0 ± 1.8 years). Forty-six patients met the criteria for a diagnosis of POTS, and the remaining 67 patients were placed in the non-POTS group. None of the patients who fulfilled the HR criteria for POTS were taking any tachycardia-promoting medications. Patients with POTS were much younger than non-POTS subjects (P < .001), and the POTS group tended to include more females than males. Patients with longer history of

Discussion

The present study reveals that the diurnal variability in OT significantly influences the diagnosis of POTS. The morning OVS showed better sensitivity in diagnosing POTS; however, this was not applicable to every individual case. Additionally, we demonstrate the diurnal variability of the provoked symptoms during the OVS test, which was present in less than half of the POTS patients during two OVS tests. Moreover, we suggest that OH, especially when preceded by OT, should not lead to rejection

Acknowledgments

Author contributions: J.M., H.S.L., and K.C. contributed to the study concept and design; J.M., H.S.L., T-.J.K., and K.C. performed the acquisition of data; J.M., H.S.L., J-.I.B., J-.W.S., Y-.W.S., and K-.J.L. analyzed and interpreted the data; J-.S.S., D.J., K-.H.J., S-.T.L., K-.Y.J., and S.K.L. performed the critical revision of the manuscript for important intellectual content; K.C. and S.K.L. did the study supervision.

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    Conflict of interest: All the authors report no conflict of interest.

    This study was supported by a grant from the Korean Health Technology R&D Project of the Ministry of Health and Welfare, Republic of Korea (HI13C1558).

    1

    These two authors contributed equally to this work.

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