Tilt Testing Remains a Valuable Asset

Richard Sutton; Artur Fedorowski; Brian Olshansky; J. Gert van Dijk; Haruhiko Abe; Michele Brignole; Frederik de Lange; Rose Anne Kenny; Phang Boon Lim; Angel Moya; Stuart D. Rosen; Vincenzo Russo; Julian M. Stewart; Roland D. Thijs; David G. Benditt

Disclosures

Eur Heart J. 2021;42(17):1654-1660. 

In This Article

Current Status of Tilt Testing

A positive TT has diagnostic value in syncope/collapse when the history does not provide a conclusive explanation for symptoms.[10,11] If the history yields a clear diagnosis, TT is not required; nonetheless, TT may provide important patient education and reassurance, together with pathophysiological evidence of the underlying mechanisms, critical for the selection of appropriate therapy.[12]

The methodology and interpretation of TT results have evolved since it was introduced into clinical practice.[1] Initially, prolonged TTs, up to 2 h at angles 40–60°, were used to trigger vasovagal events in susceptible individuals. Subsequently, test duration was shortened, head-up angle was defined as 60–80°, and other interventions were added to improve test sensitivity.[13–21] These interventions included administration of drugs (e.g. isoproterenol, nitroglycerine, serotonin agonists) alone or in conjunction with physical manoeuvres, such as carotid sinus massage. Several of these provocative measures improved TT sensitivity and remain in use; however, their addition may reduce specificity.

Regarding TT for evaluating the syncope of unknown origin, Forleo et al.[22] reported a meta-analysis of 55 studies incorporating patients with unexplained syncope and asymptomatic controls without history of syncope. The authors excluded studies with <10 patients and procedures with tilt angulation <60° or >80°; the evaluation thereby comprised 4361 patients with syncope (aged 41 ± 17 years) and 1791 controls (aged 39 ± 17 years). The summary receiver-operating curve demonstrated good overall ability to differentiate symptomatic patients from asymptomatic controls with an area under the curve of 0.84 [95% confidence interval (CI) 0.81–0.87]. As expected, pharmacological protocols enhanced sensitivity but reduced specificity. Tilt protocols that included nitroglycerine provocation had the highest diagnostic odds ratio (14.40; 95% CI 11.50–18.05) and greatest sensitivity (66%; 95% CI 60–72%).

Given the preponderance of evidence, and working independently (a few members of each group provided reviews of the other document), the European Society of Cardiology (ESC)[10] and the American College of Cardiology/American Heart Association/Heart Rhythm Society collaboration[11] arrived at similar and closely coherent recommendations for TT in unexplained syncope after initial clinical assessment [i.e. detailed history and basic examination including electrocardiogram (ECG) and orthostatic blood pressure measurement], agreeing on a class IIA indication. Furthermore, both groups proposed that when an autonomic disturbance was deemed likely, TT (with additional cardiovascular autonomic assessment, if appropriate) should be a preferred component of the diagnostic strategy.

Recent criticisms by Kulkarni et al.[9] suggest that, like any diagnostic test, TT can be inappropriately applied. Nevertheless, extensive experience, as well as evidence-based practice guideline recommendations, provides clear direction for its appropriate application and indicates when so TT is an important, effective diagnostic tool. Use of other orthostatic stressors might be contemplated (e.g. active standing, squat-stand test), but these have not undergone the scrutiny as potential clinical tools to the degree that has TT, excepting evaluation of initial and classical OH and postural orthostatic tachycardia syndrome where active standing is well recognized, supported by evidence and, thus, by guidelines.[10,11]

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