Significance of tilt table testing in patients with suspected arrhythmic syncope and negative electrophysiologic study.

BACKGROUND: The diagnostic significance of a tilt table test (TTT) in patients with a suspected arrhythmic etiology for syncope and negative electrophysiologic study (EPS) has not been previously assessed comparing the TTT results with the findings of prolonged monitoring using an implantable loop recorder (ILR). We sought to assess the diagnostic yielding of TTT in patients with suspected arrhythmic syncope and negative EPS. METHODS AND RESULTS: In 81 patients with suspected arrhythmic etiology for syncope and negative EPS, TTT was performed and an ILR implanted regardless the results of TTT. TTT was positive in 38 patients. During follow-up, syncope or presyncope recurred in 32 patients (39.5%). No differences were found in recurrence rates in patients with positive and negative TTT (31.5% vs 46.5%, P = ns). According to rhythm registered during ILR activation, mechanisms of syncopal events were classified as: arrhythmic (atrioventricular [AV] block and ventricular tachycardia; n = 18), neurally mediated (sinus bradycardia and sinus pause; n = 9), and indeterminate (normal sinus rhythm; n = 5). There was no statistical association between the results of TTT and the mechanism of syncope. CONCLUSIONS: In patients with a suspected arrhythmic etiology for syncope and a negative EPS, TTT is of little value to predict the mechanism of syncope and the ILR implantation seems to be a useful and safe diagnostic strategy.

Selective use of diagnostic tests inpatients with syncope of unknown cause.

OBJECTIVE: We sought to prospectively assess the diagnostic yielding of a protocol in which electrophysiologic studies (EPS), tilt-table tests (TTTs), and loop recorder implantation are selectively used. BACKGROUND: The optimal strategy in the diagnosis of patients with syncope of unknown cause has not been defined. METHODS: A total of 184 consecutive patients with syncope of unknown cause were classified into two groups. Group A consisted of 72 patients fulfilling any of the following criteria: 1) presence of structural heart disease or family history of sudden death; 2) abnormal electrocardiogram; 3) significant non-symptomatic arrhythmia on Holter monitoring; and 4) paroxysmal palpitations immediately before or after syncope. These patients initially underwent an EPS and, if this study was negative, TTT. In the remaining 112 patients (group B), TTT was performed. RESULTS: The EPS was positive in 32 patients (44%) in group A. The TTT was positive in 80 patients (71%) in group B. An additional patient had carotid sinus hypersensitivity. In patients of group A with a negative EPS, the TTT was positive in 23 (57%). A loop recorder was implanted in 15 patients from group A with negative conventional testing, and diagnostic activation was obtained in seven patients. Overall, a positive diagnosis was achieved in 143 patients (78%). CONCLUSIONS: In patients with syncope of unknown cause, selective use of EPS or TTT leads to a positive diagnosis in >70% of the cases. An implantable loop recorder can be useful in non-diagnosed cases.