Predictor of a negative tilt-table test result based on early heart rate variation in patients with a history of syncope

Syncope as a health risk for soldiers - influence of medical history and clinical findings on the sensitivity of head-up tilt table testing

BACKGROUND

Syncope is a relevant health problem in military environments. Reliable diagnosis is challenging. Tilt table testing is an important tool for syncope diagnosis. The aim of this study was to determine whether signs such as prodromal symptoms, co-morbidity, frequency of syncopal events, body length, body mass index, and electrocardiography abnormalities can be used to predict the success of tilt table testing at diagnosing syncope.

METHODS

Data from 100 patients with histories of syncope or pre-syncope, who were diagnosed using head-up tilt table testing, were retrospectively analyzed in a cross-sectional analysis. The diagnostic procedure was based upon a modified version of the Westminster protocol without any pharmacological provocation.

RESULTS

Patients showing pathological reaction patterns during tilt table testing suffered from prodromal symptoms, such as dizziness and sweating, significantly more often. The patients reported more injuries resulting from syncopal events and more previous syncopal events, and the prevalence of co-morbidity was greater among patients presenting negative findings during tilt testing. An asthenic-leptosomal physique was not confirmed as a risk factor for syncopal events as is the case for idiopathic arterial hypotension. However, patients with pathological reaction patterns during tilt table testing were significantly taller. This finding was detected for both females and males. No significant predictors were found in the electrocardiogram (ECG) patterns of patients showing syncope during tilt table testing.

CONCLUSIONS

Frequency of prior syncope and prodromal symptoms, and increased body length with an otherwise good state of health influence the predictive value of tilt table testing for syncope diagnosis. In particular, if these factors are present, tilt table testing should be considered part of the diagnostic algorithm for soldiers with recurrent syncope.

Orthostatic tolerance is difficult to predict in recurrent syncope patients

OBJECTIVES

We tested the hypothesis that detailed anthropometric and hemodynamic measurements predict orthostatic tolerance in neurally mediated syncope patients. In addition, we tested whether orthostatic tolerance is related to syncope frequency in real life.

BACKGROUND

Earlier studies in patients with neurally mediated syncope suggested that orthostatic heart rate and blood pressure responses predict the tilt table responses with high sensitivity and specificity.

METHODS

We analyzed data from 157 consecutive patients (n = 100 exploratory cohort, n = 57 confirmatory cohort) with recurrent syncope in whom orthostatic tolerance was quantified as the time to (pre)syncope during head-up tilt testing combined with lower body negative pressure. We measured heart rate, brachial blood pressure, cardiac stroke volume, heart rate and blood pressure variability, and spontaneous baroreflex sensitivity supine and early during head-up tilt.

RESULTS

The orthostatic heart rate increase showed the strongest correlation with orthostatic tolerance. The best multivariate model including age, supine diastolic blood pressure, supine blood pressure variability, as well as tilt-induced changes in diastolic blood pressure and heart rate explained no more that 40% of the variability in orthostatic tolerance. The model failed to predict orthostatic tolerance in the confirmatory cohort. Frequency or number of free-living syncopal episodes were only weakly related to orthostatic tolerance.

CONCLUSIONS

In patients with neurally mediated syncope, orthostatic tolerance in the clinical laboratory is difficult to predict with a wide range of anthropometric and cardiovascular measurements and correlates poorly with syncope occurrence in real life.