title: A prospective randomized comparison of loop recorders versus Holter monitors in patients with syncope or presyncope.
abstract: BACKGROUND
  The initial management of syncope or presyncope typically involves short-term cardiac monitoring using a Holter monitor. A loop recorder is used to extend the period of monitoring to increase the probability of obtaining a symptom-rhythm correlation. Loop recorders and Holter monitors are both used commonly, but their utility has not been compared prospectively.
  
  
  METHODS
  Patients with syncope or presyncope referred for a Holter monitor or a loop recorder were assigned randomly to receive either a 48-hour Holter monitor or a loop recorder for 1 month as an initial diagnostic strategy. If the initial strategy was unsuccessful, patients were offered crossover to the alternate strategy.
  
  
  RESULTS
  One hundred patients (mean [+/- SD] age, 56 +/- 20 years; 44 women) with syncope (n = 21), presyncope (n = 29), or both (n = 50) were enrolled. Of the 49 patients assigned randomly to an external loop recorder first, 31 (63%) had an arrhythmia identified or excluded, versus 12 (24%) of 51 patients assigned to a Holter monitor initially (P <0.0001). Arrhythmia was identified as a cause of syncope in 1 patient with a loop recorder, compared with no patients with a Holter monitor (P = 0.31). Of the 29 patients with negative results with Holter monitoring who went on to receive a loop recorder, 13 (45%) had arrhythmia excluded, compared with none of the 4 patients who crossed over to receive a Holter monitor. The overall probability of obtaining a symptom-rhythm correlation was 56% (44/78) for loop recorders versus 22% (12/55) for Holter monitors (P <0.0001). Despite patient education and test transmissions, 13 (23%) of 57 patients who had recurrence of their symptoms failed to activate their loop recorder properly.
  
  
  CONCLUSIONS
  Loop recorders have a much higher diagnostic yield for patients with syncope or presyncope as compared with Holter monitors. The utility of loop recorders is limited by some patients' inability to operate them correctly.
authors.affiliation: Division of Cardiology, University of Western Ontario, London, Ontario, Canada.
authors.forename: Soori
authors.initials: S
authors.lastname: Sivakumaran
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Krahn
authors.forename: George J
authors.initials: GJ
authors.lastname: Klein
authors.forename: Jane
authors.initials: J
authors.lastname: Finan
authors.forename: Raymond
authors.initials: R
authors.lastname: Yee
authors.forename: Suzanne
authors.initials: S
authors.lastname: Renner
authors.forename: Allan C
authors.initials: AC
authors.lastname: Skanes
mesh_terms: D015716:Electrocardiography, Ambulatory / Q000295:instrumentation*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012720:Severity of Illness Index; D013575:Syncope / Q000175:diagnosis*; D013997:Time Factors