Early versus late postural tachycardia: a re-evaluation of a syndrome

Sinus Tachycardia: a Multidisciplinary Expert Focused Review

Sinus tachycardia (ST) is ubiquitous, but its presence outside of normal physiological triggers in otherwise healthy individuals remains a commonly encountered phenomenon in medical practice. In many cases, ST can be readily explained by a current medical condition that precipitates an increase in the sinus rate, but ST at rest without physiological triggers may also represent a spectrum of normal. In other cases, ST may not have an easily explainable cause but may represent serious underlying pathology and can be associated with intolerable symptoms. The classification of ST, consideration of possible etiologies, as well as the decisions of when and how to intervene can be difficult. ST can be classified as secondary to a specific, usually treatable, medical condition (eg, pulmonary embolism, anemia, infection, or hyperthyroidism) or be related to several incompletely defined conditions (eg, inappropriate ST, postural tachycardia syndrome, mast cell disorder, or post-COVID syndrome). While cardiologists and cardiac electrophysiologists often evaluate patients with symptoms associated with persistent or paroxysmal ST, an optimal approach remains uncertain. Due to the many possible conditions associated with ST, and an overlap in medical specialists who see these patients, the inclusion of experts in different fields is essential for a more comprehensive understanding. This article is unique in that it was composed by international experts in Neurology, Psychology, Autonomic Medicine, Allergy and Immunology, Exercise Physiology, Pulmonology and Critical Care Medicine, Endocrinology, Cardiology, and Cardiac Electrophysiology in the hope that it will facilitate a more complete understanding and thereby result in the better care of patients with ST.

Functional capacity and quality of life in the postural tachycardia syndrome: A retrospective cross-sectional study

Background

Postural tachycardia syndrome (POTS) is a complex syndrome of orthostatic intolerance that significantly affects quality of life. The relationship between functional capacity, quality of life, and age remains poorly understood in this patient population. The purpose of this cross-sectional study was to assess the clinical and exercise characteristics of patients with POTS who underwent exercise stress testing as part of cardiac rehabilitation, and to evaluate the relationships between functional capacity with age and sex, as well as the relationship between functional capacity and quality of life.

Methods

We included 255 consecutive adult patients with the diagnosis of POTS, by tilt table testing, who underwent exercise stress testing between 2012 and 2017. Clinical and stress test data were obtained from electronic medical records.

Results

Of the 255 patients, 232 (91%) were women, with median age 33.5 years. Prevalence of traditional CAD risk factors was low (2% diabetes, 13% hypertension, 7% hyperlipidemia, and 26% smoking history). Mean resting BP was 114 ± 13 mmHg systolic, resting HR was 76 ± 13 bpm, METs achieved 9.2 ± 2.2, and 1 min HR recovery 32 ± 17 bpm. 113 patients (44%) had abnormal functional capacity for age and sex. When analyzed by age groups, younger POTS patients had increasingly lower than expected functional capacity (compared to predicted normals) than did older patients (ANOVA P = 0.0017). The SF-36 physical component of patients with abnormal functional capacity was significantly lower than those with normal functional capacity. (p = 0.006).

Conclusions

In this large cohort, patients with POTS were predominantly female (91%) and relatively young. The novel findings are that younger patients with POTS were more likely to have lower-than-average functional capacity for their age and sex compared to older patients, and that abnormal functional capacity was associated with lower quality of life by SF-36 physical component.

ST-segment changes during tilt table testing for postural tachycardia syndrome: correlation with exercise stress test results

BACKGROUND

Prior studies have reported ECG (Electrocardiogram) changes during tilt table testing (TTT), specifically during repolarization with ST-segment and T-wave changes. The correlation with ischemic evaluation remains unclear. The purpose of this study was to analyze the prevalence of ST-segment changes during TTT in a young, otherwise healthy population of patients with postural tachycardia syndrome (POTS), and correlate them with exercise stress test results.

METHODS

Two hundred and fifty-five patients with POTS who underwent TTT and an exercise treadmill test (ETT) were analyzed.

RESULTS

Forty-five had ST-segment changes/depressions during TTT (91% female, average age 36 years). Of the 45, three had ST-segment depression during ETT; all three had negative exercise stress echocardiograms (ESEs). Two others had ST-segment depressions on ETT (but not TTT), with negative ESEs.

CONCLUSION

In a cohort of young, female, otherwise healthy patients with POTS, ST-segment changes occurred in a significant portion (18%) of patients during TTT. When evaluated with exercise stress testing, these patients had no evidence of underlying ischemia on ETT or ESE.

Orthostatic tachycardia with different onset time in patients with orthostatic intolerance

OBJECTIVE

To investigate whether there is a difference in the neuro-autonomic and hemodynamic parameters in patients with postural tachycardia syndrome (POTS) according to onset time of orthostatic tachycardia during the Head-up tilt (HUT) test.

METHODS

We retrospectively reviewed neuro-autonomic and hemodynamic data from patients with orthostatic intolerance. A standardized battery of neuro-autonomic tests, including the HUT, Valsalva maneuver, heart rate deep breathing and quantitative sudomotor axon reflex test, was performed. The beat-to-beat derived hemodynamic parameters, including systolic blood pressure (BP) (SBP), mean BP (MBP), diastolic BP, heart rate (HR), total peripheral resistance, stroke volume, and cardiac output, were also extracted from HUT test. According to onset time of orthostatic tachycardia (OT), we divided patients into two groups; HR increase "within 10 minutes" (i.e., early OT) and HR increase "after 10 minutes" (i.e., late OT).

RESULTS

We identified 210 patients with OT during HUT test. Forty-three percent of patients were included in early OT group and 57% were late OT group. Patients in late OT group were older than early OT group. Late OT group tended to have baseline hypertension more frequently compared to early OT group. After adjusting for age, late OT group showed higher baseline SBP and MBP, and lower increase of HR during HUT test than early OT group. However, other neuro-autonomic and hemodynamic parameters did not show significant differences between two groups.

CONCLUSION

Orthostatic tachycardia might be developed in the late period during the HUT test. There were no remarkable differences in neuro-autonomic and hemodynamic parameters between early and late OT groups. It seems reasonable to extend the duration of HUT test to at least 20 min, to increase the diagnostic yield in patients with a history of orthostatic intolerance suspected as having POTS.

Postural Tachycardia Syndrome and Vasovagal Syncope: A Hidden Case of Obstructive Cardiomyopathy without Severe Septal Hypertrophy

A 36-year-old female with symptoms of orthostatic intolerance and syncope was diagnosed with vasovagal syncope on a tilt table test and with postural tachycardia syndrome (POTS) after a repeat tilt table test. However, an echocardiogram at our institution revealed obstructive cardiomyopathy without severe septal hypertrophy, with a striking increase in left ventricular outflow tract gradient from 7 mmHg at rest to 75 mmHg during Valsalva, with a septal thickness of only 1.3 cm. Cardiac MRI showed an apically displaced multiheaded posteromedial papillary muscle with suggestion of aberrant chordal attachments to the anterior mitral leaflet contributing to systolic anterior motion of the mitral valve. She underwent surgery with reorientation of the posterior medial papillary muscle head, resection of the tethering secondary chordae to the A1 segment of the mitral valve, chordal shortening and tacking of the chordae to the A1 and A2 segments of the mitral valve, and gentle septal myectomy. After surgery, she had significant improvement in her prior symptoms. To our knowledge, this is the first reported case of obstructive cardiomyopathy without severe septal hypertrophy with abnormalities in papillary muscle and chordal attachment, in a patient diagnosed with vasovagal syncope and POTS.

Patients with Orthostatic Intolerance: Relationship to Autonomic Function Tests results and Reproducibility of Symptoms on Tilt

This study was designed to investigate the frequency and pattern of orthostatic symptoms during head-up tilt (HUT) in patients with orthostatic intolerance during daily life, and to identify the relationship between the orthostatic symptoms during HUT and autonomic parameters. We prospectively collected autonomic data from 464 patients with orthostatic symptoms. Adrenergic and cardiovagal function tests including HUT were performed. Based on HUT results, we divided patients into orthostatic hypotension (OH), postural tachycardia syndrome (POTS), or normal HUT groups. We also investigated orthostatic symptoms during HUT. Only 25% of the patients reported orthostatic symptoms during HUT and 75% were asymptomatic. Typical orthostatic symptoms such as orthostatic dizziness and blurred vision, and atypical symptoms like chest tightness and headache occurred in 86% and 66%, respectively. Patients with POTS had symptoms more frequently than patients with OH during HUT. There were no differences in degrees of BP or HR changes between symptomatic and asymptomatic groups within the OH and POTS groups. HUT fails to reproduce symptoms of orthostatic intolerance in the majority of patients. Clinicians need to be aware that most patients with OH are asymptomatic during HUT and patients with POTS are more likely to be symptomatic than patients with OH.

Characteristics of heart rate reduction with resumption of supine position in the postural tachycardia syndrome: factors influencing recovery

Objectives:

Postural orthostatic tachycardia syndrome (POTS), a heart rate (HR) rise with upright positioning, is dependent on autonomic influences. HR recovery (HR decrease after exercise cessation) is a measure of autonomic function. Characteristics of HR reduction during supine Recovery after head-up Tilt in POTS patients have not been elucidated.

Methods:

113 subjects (mean age 41.7 years, 86 female), diagnosed with POTS on head-up Tilt were analyzed. HR’s were recorded during baseline supine position, 70-degree Tilt, and 20 sec, 1 min and 2 min of supine Recovery. Percent HR reduction during Recovery was calculated.

Results:

Baseline HR was 68.7±13.4 bpm. Maximum HR during Tilt was 109±16.9 bpm. Mean HR was 84.2±20 bpm at 20 sec, 78.5±18.9 bpm at 1-min, and 77.1±18.3 bpm at 2 min of Recovery. Younger age and slower baseline HR were associated with greater HR reductions at 20 sec (p=0.006, p=0.000, respectively). Younger age, slower baseline HR and less time to achieve POTS were associated with greater HR reductions at 1 min (p=0.025, p=0.000, p=0.000, respectively) and at 2 min (p=0.004, p=0.000, p=0.000, respectively). Gender and baseline blood pressures were not significant.

Conclusions:

In POTS patients, HR quickly decreases upon resuming supine position. Younger age, slower baseline HR and less time to achieve POTS were associated with greater HR reductions during supine Recovery. Further study is needed to determine mechanisms, as well as analyze differences in symptoms or prognosis.

Diagnosing postural tachycardia syndrome: comparison of tilt testing compared with standing haemodynamics

POTS (postural tachycardia syndrome) is characterized by an increased heart rate (ΔHR) of ≥30 bpm (beats/min) with symptoms related to upright posture. Active stand (STAND) and passive head-up tilt (TILT) produce different physiological responses. We hypothesized these different responses would affect the ability of individuals to achieve the POTS HR increase criterion. Patients with POTS (n=15) and healthy controls (n=15) underwent 30 min of tilt and stand testing. ΔHR values were analysed at 5 min intervals. ROC (receiver operating characteristic) analysis was performed to determine optimal cut point values of ΔHR for both tilt and stand. Tilt produced larger ΔHR than stand for all 5 min intervals from 5 min (38±3 bpm compared with 33±3 bpm; P=0.03) to 30 min (51±3 bpm compared with 38±3 bpm; P<0.001). Sn (sensitivity) of the 30 bpm criterion was similar for all tests (TILT10=93%, STAND10=87%, TILT30=100%, and STAND30=93%). Sp (specificity) of the 30 bpm criterion was less at both 10 and 30 min for tilt (TILT10=40%, TILT30=20%) than stand (STAND10=67%, STAND30=53%). The optimal ΔHR to discriminate POTS at 10 min were 38 bpm (TILT) and 29 bpm (STAND), and at 30 min were 47 bpm (TILT) and 34 bpm (STAND). Orthostatic tachycardia was greater for tilt (with lower Sp for POTS diagnosis) than stand at 10 and 30 min. The 30 bpm ΔHR criterion is not suitable for 30 min tilt. Diagnosis of POTS should consider orthostatic intolerance criteria and not be based solely on orthostatic tachycardia regardless of test used.

Orthostatic intolerance and the headache patient

Orthostatic intolerance (OI) refers to a group of clinical conditions, including postural orthostatic tachycardia syndrome (POTS) and neurally mediated hypotension (NMH), in which symptoms worsen with upright posture and are ameliorated by recumbence. The main symptoms of chronic orthostatic intolerance syndromes include light-headedness, syncope or near syncope, blurring of vision, headaches, problems with short-term memory and concentration, fatigue, intolerance of low impact exercise, palpitations, chest pain, diaphoresis, tremulousness, dyspnea or air hunger, nausea, and vomiting. This review discusses what is known about the pathophysiology of this disorder, potential treatments, and understanding its role in the patient with chronic headache pain.