title: Mechanism of syncope in patients with heart disease and negative electrophysiologic test.
abstract: BACKGROUND
  In patients with syncope and structural heart disease, syncope is suspected to be attributable to a primary cardiac arrhythmia, but little is known of its mechanism when electrophysiologic study is unremarkable.
  
  
  RESULTS
  We applied an implantable loop recorder in 35 patients with overt heart disease at risk of ventricular arrhythmia, because these were patients with previous myocardial infarction or cardiomyopathy with depressed ejection fraction or nonsustained ventricular tachycardia in whom an electrophysiologic study was unremarkable. During a follow-up of 3 to 15 months, syncope recurred in 6 patients (17%) after a mean of 6+/-5 months; in 3 patients, the mechanism of syncope was bradycardia with long pauses (sudden-onset AV block in 2 cases and sinus arrest in 1 case); in 1 patient, there was stable sinus tachycardia; and in 2 patients, who had chronic atrial fibrillation, there was an increase in ventricular rate. A total of 23 episodes of presyncope were documented in 8 patients (23%): no rhythm variation or mild tachycardia in 12 cases, paroxysmal atrial fibrillation or atrial tachycardia in 10 cases, and sustained ventricular tachycardia in 1 case. No patient died during the study period nor suffered from injury attributable to syncopal relapse.
  
  
  CONCLUSIONS
  The patients with unexplained syncope, structural heart disease, and negative electrophysiologic study had a favorable medium-term outcome with no case of death and a low recurrence rate of syncope without related injury. The mechanism of syncope was heterogeneous, and ventricular tachyarrhythmia was unlikely.
authors.affiliation: Department of Cardiology, Ospedale S. Maria Nuova, Reggio Emilia, Italy.
authors.forename: Carlo
authors.initials: C
authors.lastname: Menozzi
authors.forename: Michele
authors.initials: M
authors.lastname: Brignole
authors.forename: Roberto
authors.initials: R
authors.lastname: Garcia-Civera
authors.forename: Angel
authors.initials: A
authors.lastname: Moya
authors.forename: Gianluca
authors.initials: G
authors.lastname: Botto
authors.forename: Luis
authors.initials: L
authors.lastname: Tercedor
authors.forename: Roberta
authors.initials: R
authors.lastname: Migliorini
authors.forename: Xavier
authors.initials: X
authors.lastname: Navarro
mesh_terms: D000368:Aged; D001145:Arrhythmias, Cardiac / Q000150:complications* / Q000175:diagnosis; D009202:Cardiomyopathies / Q000150:complications* / Q000175:diagnosis; D018572:Disease-Free Survival; D004562:Electrocardiography; D022062:Electrophysiologic Techniques, Cardiac; D023381:Endpoint Determination; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D019736:Prostheses and Implants; D013575:Syncope / Q000209:etiology*