(P148) TILT TESTING OR IMPLANTABLE CARDIAC MONITORING IN THE DIAGNOSIS OF UNEXPLAINED SYNCOPE

Background: After an initial evaluation many older syncope patients do not receive a diagnosis for their syncope. Both head-up tilt-tests (HUTT) and implanted loop recorders (ILR) are recommended but there is no consensus about which should be done first. We tested the hypothesis that first conducting an HUTT provided a higher, earlier diagnostic yield than first implanting an ILR.

METHODS AND RESULTS: This was a single centre, open-label, retrospective, comparative analysis. Data were extracted from clinical databases with secondary chart review. Inclusion criteria were age ≥ 5o years, and no diagnosis after clinical and ECG evaluation. Exclusion criteria included heart failure, reduced LVEF, and ECG conduction abnormalities. The primary outcome was a etiologic diagnosis of syncope within 1 year; secondary outcomes included time to diagnosis and the proportion with a syncope diagnosis at end of follow-up. There were 233 patients (135 males), mean age 69 years, with a median 3 historical syncopes. There were 104 and 129 patients in the HUTT and ILR groups, respectively. Baseline clinical variables were similar except the ILR group had more frequent injuries, therapy with beta-blockers, diuretics, or CV medications. The median observation periods were 842 days and 483 days in the ILR and HUTT groups, respectively. After one year of followup there were 65/104 and 37/129 diagnostic outcomes in the HUTT and ILR groups, respectively (p < 0.00001, Fisher exact). There were more diagnostic outcomes in the HUTT arm by study completion (65/104 HUTT vs 58/129 ILR {p = 0.0055). The median times to a syncope diagnosis were 0.03 months and 23 months in the HUTT and ILR groups respectively (hazard ratio 8.62; odds ratio 2.04 (1.20, 3.46, p < 0.01). Two patients died in the ILR group, both of unrelated causes.

Conclusion: In this retrospective analysis of older patients with syncope of unknown etiology first conducting an HUTT provided an earlier, higher diagnostic yield than first implanting an ILR.