Palpitations: event recorders detected more arrhythmias than Holter monitoring.

Clinical bottom line (level 1b)

  1. In patients with palpitations, event recorders produced more interpretable ECG tracings with symptoms (NNT = 3 at unknown) , and detected more clinically important arrhythmias than 48 hours of Holter monitoring (NNT = 5 at unknown) .
  2. Event monitoring was cheaper.
Kinlay et al: Annals of Internal Medicine 1996; 124 (1): 16-20
Expires October 2004

The study

Single-blinded ?concealed randomised cross-over trial without intention-to-treat
Setting: cardiovascular unit, teaching hospital, Australia

45 patients (aged mean 45 years, 88% female) palpitations referred for Holter monitoring.

Excluded if
  • too old, too feeble, or too young to use event monitor
  • required monitoring for silent ischaemia, assessment of therapy, syncope or other research studies
  • previously had Holter monitoring for symptoms
  • could not be interviewed


    • Control Group: (n = 45, 43 analysed): 48 hr Holter monitoring, then swapped
    Experimental Group: (n = 45, 43 analysed): event monitor until two recordings during symptoms, otherwise for three months then swapped

    96% followed for 3 months
    Outcome notes:
    • clinically important arrhythmia detected : symptomatic sustained supraventricular tachycardia (SVT> 15 beats/ min); atrial fibrillation or flutter; sustained ventricular tachycardia (ventricular rate > 10 beats/min); sinus pause > 3 seconds; non-Wenkebach second degree heart block; third degree heart block

    The evidence

    Outcome Time to outcome CEREERRRR
    (95% CI)    		ARR
    (95% CI)    		NNT
    (95% CI)
    clinically important arrhythmia detected 3 months 0
    (0.00%)    		 8
    (18.6%)    		 %
    (% to %)    		 -18.6%
    (-30.2% to -6.97%)    		 5
    (3 to 14)

    Outcome Control Group
    (SD)    		 Experimental Group
    (SD)    		 Mean Difference
    (95% CI)
    costs (Australian $) 4245 (range 2650 to 4994)
    ()     		1258 (range 1049 to 1471)
    ()     		-2987
    ( to )

  • uninterpretable ECG tracing (rhythm strip recorded during symptoms - read by blinded cardiologist) 65.1% of Holter monitor events, and only 32.6% of Event-monitor events
  • Cost per additional ECG recorded during symptoms = -$213.
  • Cost per additional clinically significant arrhythmia detected = -$373.
  • Clinically important arrhythmias: six SVT and two AF or flutter.
  • Most patients on event recorders had ECG recording by 6 weeks.

    • Citation

    1. Kinlay S, Leitch JW, Neil A, et al: Cardiac event recorders yield more diagnoses and are more cost-effective than 48-hour Holter monitoring in patients with palpitations. A controlled clinical trial. Annals of Internal Medicine 1996; 124 (1): 16-20
    Contributor: Chris Ball and Clare Wotton, October 2000
    Reviewer:

    Clinical Question.
    Patient palpitations
    Intervention or Exposure event recorders
    Comparison 48 hour Holter monitoring
    Outcome interpretable ECG tracings, cost