Cardiac Pacing pp 729-733 | Cite as

Comparison of Clinical Significance of Programmed Stimulation Induced Ventricular Tachycardia and Fibrillation in Survivors of Acute Myocardial Infarction

  • L. K. Holley
  • A. R. Denniss
  • D. V. Cody
  • S. M. Fenton
  • D. A. Richards
  • D. L. Ross
  • P. A. Russell
  • A. A. Young
  • J. B. Uther

Summary

The clinical significance of ventricular tachycardia and ventricular fibrillation induced at electrophysiology studies was examined in 64 patients (pts) studied after transmural acute myocardial infarction. Ten patients had had documented late ventricular arrhythmias prior to the electrophysiology study. The stimulation protocol included 2 extrastimuli (S1S2, S2S3) delivered after a paced rhythm at 2 right ventricular sites (apex, outflow tract) and at 2 current intensities (2x threshold, 20 mA). Patients were followed for 6–18 months after the study.

Of the fiftyfour patients with no documented ventricular arrhythmia, 23 were induced into fibrillation (group I), and 31 into tachycardia (group 2). All patients with documented ventricular arrhythmias were induced into tachycardia (group 3). There was no difference in patient age or infarct site amongst the three groups. Apart from two patients with an infarct age of greater than I year, infarcts to study time was greater than 1.5 weeks and less than 3 months S1S2 was not significantly different among the groups but S2S3 was significantly longer (242 msec ± 33) in group 3 than groups I and 2 (200 msec ± 40, 206 msec ± 41), p < 0.05. Minimum pacing amplitude to induce an arrhythmia was significantly lower in group 3 (10% at 20 mA) than in groups I and 2 (65% and 55%). None of the patients in group I died of cardiac causes while 27% of the patients in group 2 died of cardiac cause. The mean rate of the induced VT from the pts who died was slower, 244 ± 45 ppm than that of the VT in pts still alive 281 ± 44 ppm (p < 0.05). Fifty per cent of the patients in group 3 died of a cardiac cause.

The results indicate that after acute myocardial infarction (1) induced slow rate VT during an electrophysiology study is associated with a poorer prognosis than VF and fast VT; (2) induced VF may be of limited clinical significance. (3) VT is inducible with less aggressive stimulation in pts with documented ventricular arrhythmias.

Keywords

Catheter Platinum Dial Fenton 

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References

  1. 1.
    Richards DA, Cody DV, Denniss AR, Russell PA, Young AA, Uther JB: Ventricular electrical instability: a predictor of death after myocardial infarction. Am J Cardiology 1983; 51: 75–80.CrossRefGoogle Scholar
  2. 2.
    Holley LK, Goodman AH, Richards DAB, Uther JB: Computer modelling of the electrical activation of the ventricular myocardium and re-entrant ventricular arrhythmias. Aust N Z J Med 1982; 12: 314.CrossRefGoogle Scholar
  3. 3.
    Denniss AR, Richards DA, Farrow RH, Davison A: Use of the signal averaged vectorcardiogram to predict ventricular electrical instability after myocardial infarction. Circulation 1982; 66: 11–16.Google Scholar
  4. 4.
    Richards DA, Cody DV, Denniss AR, Russell PA, Young AA, Uther JB: A new protocol of programmed stimulation for assessment of predisposition to spontaneous ventricular arrhythmias. Eur Heart J 1983 (in press)Google Scholar

Copyright information

© Dr. Dietrich Steinkopff Verlag, GmbH & Co. KG, Darmstadt 1983

Authors and Affiliations

  • L. K. Holley
    • 1
  • A. R. Denniss
    • 2
  • D. V. Cody
    • 2
  • S. M. Fenton
    • 2
  • D. A. Richards
    • 2
  • D. L. Ross
    • 2
  • P. A. Russell
    • 2
  • A. A. Young
    • 2
  • J. B. Uther
    • 2
  1. 1.Bioengineering Research CentreTelectronics Pty. Ltd.SydneyAustralia
  2. 2.Cardiology UnitWestmead CentreSydneyAustralia

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