The Diagnostic Sensitivity of Electrophysiologic Testing in Patients with Syncope Caused by Transient Bradycardia

• Published in: The New England journal of medicine Vol. 321; no. 25; pp. 1703 - 1707
• Main Authors: Fujimura, Osamu, Yee, Raymond, Klein, George J, Sharma, Arjun D, Boahene, K. Atta
• Format: Journal Article
• Language: English
• Published: Boston, MA Massachusetts Medical Society 21.12.1989
• Subjects: Aged; Aged, 80 and over; Biological and medical sciences; Bradycardia - complications; Bradycardia - diagnosis; Bradycardia - physiopathology; Cardiac arrhythmia; Electrocardiography; Electrocardiography. Vectocardiography; Electrodiagnosis. Electric activity recording; Female; Heart Block - physiopathology; Humans; Investigative techniques, diagnostic techniques (general aspects); Male; Medical sciences; Middle Aged; Patients; Prospective Studies; Syncope - etiology; Syncope - physiopathology; Human; Electrodiagnosis; Sensitivity; Arrhythmia; Syncope; Electrocardiography; Cardiovascular disease; Exploration; Sinus bradycardia; Diagnosis
• ISSN: 0028-4793; 1533-4406
• DOI: 10.1056/NEJM198912213212503

Although electrophysiologic testing accurately delineates abnormalities in patients with fixed cardiac-conduction defects, its sensitivity in identifying transient rhythm disturbances is unknown. We prospectively studied 21 patients who had electrocardiographically documented intermittent atrioventricular block (n = 13) or sinus pauses (n = 8) causing syncope, but whose cardiac rhythm had reverted to normal by the time of referral. There were 14 men and 7 women, with a mean age (±SD) of 63±13 years. Fourteen patients had organic heart disease, and 8 were taking cardioactive medications. Electrophysiologic testing was performed before the implantation of a permanent pacemaker. Only three of the eight patients with documented sinus pauses had abnormalities during their tests that suggested the correct diagnosis (sensitivity, 37.5 percent), including a prolonged sinus-node recovery time in one and carotid-sinus hypersensitivity in two. Three of the eight patients had abnormalities detected that were unrelated to syncope, including atrial flutter, dual atrioventricular nodal pathways, and sustained monomorphic ventricular tachycardia. Of the 13 patients with documented atrioventricular block, only 2 had abnormalities suggesting the correct diagnosis (sensitivity, 15.4 percent). Additional observations unrelated to syncope among these 13 patients included abnormal sinus-node function, atrial flutter, and atrial fibrillation causing hypotension. These preliminary observations suggest that a negative electrophysiologic test in a patient with a normal cardiac rhythm who has experienced syncope does not exclude a transient bradyarrhythmia as a cause of the syncope. Furthermore, electrophysiologic testing may sometimes reveal unrelated rhythm disturbances that may mistakenly be designated as the cause of the syncope. (N Engl J Med 1989; 321:1703–7.) TRANSIENT loss of consciousness may be caused by intermittent atrioventricular block or sinus-node dysfunction. 1 , 2 When syncope occurs infrequently and the electrocardiogram is otherwise normal, it may be difficult to obtain electrocardiographic evidence of the causative arrhythmia. 3 4 5 6 7 8 Intracardiac recording and programmed electrical stimulation are capable of detecting abnormalities of atrioventricular conduction and sinus-node function and have been used to establish a diagnosis in patients who have intermittent syncope with no apparent cause. 3 4 5 6 7 In the presence of persistent abnormalities, electrophysiologic testing is of undisputed value in the assessment of conduction defects in patients with structural heart disease. 9 However, the population of patients . . .