Ventricular tachyarrhythmia: electrophysiologic testing was no better than Holter monitoring at determining treatment.

Clinical bottom line (level 1b)

  1. Patients with ventricular arrhythmias who were allocated antiarrhythmic medication on the basis of electrophysiologic testing compared with Holter monitoring were not less likely to have recurrent arrhythmias.
  2. Electrophysiologic testing was less likely to predict drug efficacy than Holter monitoring.
Mason et al: New England Journal of Medicine 1993; 329 (7): 445-451
Expires October 2001

The study

Unblinded ?concealed randomised trial with intention-to-treat
Setting: 14 acute hospitals, USA

486 patients (aged mean 65 years, 87% male) with ECG-documented sustained ventricular fibrillation or tachycardia (lasting >15 seconds), or resuscitation from a cardiac arrest, or syncope with ECG identification of the responsible rhythm, but VT demonstrated on electrophysiologic study

Excluded if
  • ventricular tachyarrhythmia not reproducible on electrophysiologic testing
  • fewer than ten premature ventricular complexes in the previous 48 hours of monitoring


    • Control Group: (n = 244, 244 analysed): serial testing of drug efficacy using Holter monitoring
    Experimental Group: (n = 242, 242 analysed): serial testing of drug efficacy using electrophysiologic testing
    Patients could take seven antiarrhythmic drugs: imipramine, mexiletine, pirmenol, procainamide, propafenone, quinidine, sotalol
    94% followed for 6 years
    Outcome notes:
    • drug efficacy not predicted : Holter - substantial suppression of PVCs and absence of VT for 5 or more beats on exercise testing. Electrophysiologic testing - suppression of inducible ventricular tachyarrhythmias lasting longer than 15 seconds.
    • recurrence of arrhythmia : ECG documented ventricular tachyarrhythmias lasting > 15 seconds, death from arrhythmia, cardiac arrest, torsade de pointes or unmonitored syncope with no explanation other than arrhythmia

    The evidence

    Outcome Time to outcome CEREERRRR
    (95% CI)    		ARR
    (95% CI)    		NNT
    (95% CI)
    drug efficacy not predicted 4 years 56
    (23.0%)    		 134
    (55.4%)    		 -141%
    (-212% to -87%)    		 -32.4%
    (-40.6% to -24.2%)    		 -3
    (-4 to -2)
    recurrence of arrhythmia 4 years 163
    (66.8%)    		 152
    (62.8%)    		 6%
    (-7% to 18%)    		 3.99%
    (-4.49% to 12.5%)    		 25
    (NNT = 8 to infinity;
    NNH = 22 to infinity)

    Comments

    1. No clear difference in mortality was noted between the two groups.
    2. Arrhythmia recurrence was not clearly less likely to occur in patients in either group who were predicted to have effect drug therapy compared with not.

    Citation

    1. Mason JW, et al: Comparison of electrophysiologic testing with Holter monitoring to predict antiarrhythmic-drug efficacy for ventricular tachyarrhythmias. New England Journal of Medicine 1993; 329 (7): 445-451
    Contributor: Chris Ball and Clare Wotton, October 1999
    Reviewer:

    Clinical Question.
    Patient sustained ventricular tachyarrhythmia
    Intervention or Exposure electrophysiologic testing
    Comparison Holter monitoring
    Outcome predicting drug efficacy