Treatment of Unexplained Syncope: A Multicenter, Randomized Trial of Cardiac Pacing Guided by Adenosine 5'-Triphosphate Testing

• Published in: Circulation (New York, N.Y.) Vol. 125; no. 1; pp. 31 - 36
• Main Authors: FLAMMANG, Daniel, CHURCH, Timothy R, DE ROY, Luc, BLANC, Jean-Jacques, LEROY, Jean, MAIRESSE, Georges H, OTMANI, Akli, GRAUX, Pierre J, FRANK, Robert, PURNODE, Philippe
• Format: Journal Article
• Language: English
• Published: Hagerstown, MD Lippincott Williams & Wilkins 03.01.2012
• Subjects: Adenosine Triphosphate; Aged; Aged, 80 and over; Biological and medical sciences; Blood and lymphatic vessels; Cardiac Pacing, Artificial - methods; Cardiology. Vascular system; Diseases of the cardiovascular system; Diseases of the peripheral vessels. Diseases of the vena cava. Miscellaneous; Female; Follow-Up Studies; Humans; Male; Medical sciences; Middle Aged; Radiotherapy. Instrumental treatment. Physiotherapy. Reeducation. Rehabilitation, orthophony, crenotherapy. Diet therapy and various other treatments (general aspects); Single-Blind Method; Syncope - diagnosis; Syncope - physiopathology; Syncope - therapy; Treatment Outcome; vasovagal; Nervous system diseases; Purine nucleoside; Adenosine; Arrhythmia; Consciousness impairment; Multicenter study; Cardiovascular disease; Triphosphates; randomized controlled trials; Excitability disorder; Bradycardia; artificial; Treatment; Pacemaker; Syncope; Heart disease; adenosine triphosphate; Neurological disorder
• ISSN: 0009-7322; 1524-4539
• DOI: 10.1161/CIRCULATIONAHA.111.022855

The origin of 40% of syncope cases remains unknown even after a complete diagnostic workup. Previous studies have suggested that ATP testing has value in selecting successful therapy. This patient-blinded, multicenter, randomized superiority trial tested whether, in patients with syncope of unknown origin, selecting cardiac pacing in those with a positive ATP test leads to fewer recurrences than those who do not receive pacing. From 2000 to 2005, 80 consenting patients (mean age, 75.9±7.7 years; 81% women; 56% without diagnosed structural heart disease) with syncope of unknown origin and atrioventricular or sinoatrial block lasting >10 seconds (average, 17.9±6.8 seconds) under ATP administration (20-mg IV bolus) were recruited from 10 hospitals, implanted with programmable pacemakers, and randomized to either active pacing (dual-chamber pacing at 70 bpm) or backup pacing (atrial pacing at 30 bpm). Patients were followed up regularly for up to 5 years for any syncope recurrence, the primary outcome. Mean follow-up was 16 months. Syncope recurred in 8 of 39 patients (21%) randomized to active pacing and in 27 of 41 (66%) randomized to backup pacing (control), yielding a hazard ratio of 0.25 (95% confidence interval, 0.12-0.56). After recurrence, the 27 recurrent control patients were reprogrammed to active pacing, and only 1 reported subsequent syncope. This study suggests that, in elderly patients with syncope of unknown origin and positive ATP tests, active dual-chamber pacing reduces syncope recurrence risk by 75% (95% confidence interval, 44-88). URL: http://www.controlled-trials.com/ISRCTN00029383. Unique identifier: ISRCTN00029383.