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Drug therapy for ventricular tachyarrhythmias: how many electropharmacologic trials are appropriate?
K M Kavanagh1, D G Wyse, H J Duff
1Department of Medicine, Foothills General Hospital, Calgary, Alberta, Canada.
Abstract:
To determine how many electropharmacologic drug trials should be performed to select therapy for patients with ventricular tachyarrhythmias, the outcome of 150 consecutive patients with inducible ventricular tachyarrhythmias undergoing serial electropharmacologic testing was examined. The probability of identifying predicted effective therapy (inductive of fewer than five ventricular responses with three ventricular extrastimuli at three pacing cycle lengths) and the probability of that therapy preventing sustained ventricular tachyarrhythmia recurrences were determined as a function of the number of preceding trials. The probability ( +/- SE) of identifying predicted effective therapy by the first trial (0.23 +/- 0.03) was significantly higher than that of the second (0.09 +/- 0.04), third (0.08 +/- 0.04) and fourth (0.05 +/- 0.04) trials (p = 0.001). No patient had predicted effective therapy identified by subsequent trials. The 2 year actuarial probability of freedom from sustained ventricular tachyarrhythmias on predicted effective therapy was higher for the first (0.79 +/- 0.08), second (0.73 +/- 0.13) and third (0.86 +/- 0.13) trials than for the fourth (0.33 +/- 0.27) trial (p = 0.02). Thus, the probability of selecting therapy with long-term efficacy was highest for the first trial (0.18), intermediate for the second (0.07) and third (0.07) trials and lowest for the fourth (0.02) and subsequent (0.00) trials. Accordingly, the electropharmacologic approach to therapy selection should be abandoned after three unsuccessful trials.
Insights
Electrophysiologic drug testing for ventricular tachyarrhythmias should be limited. Therapy efficacy was highest after the first trial, decreasing with subsequent tests, suggesting abandoning testing after three failures.
Area of Science:
- Cardiology
- Clinical Electrophysiology
Background:
- Ventricular tachyarrhythmias pose a significant risk.
- Selecting effective antiarrhythmic therapy is crucial for patient outcomes.
- Electrophysiologic drug testing (EDT) is a common method for guiding therapy selection.
Purpose of the Study:
- To determine the optimal number of electropharmacologic drug trials for selecting therapy in patients with ventricular tachyarrhythmias.
- To evaluate the probability of identifying effective therapy and its long-term efficacy based on the number of trials performed.
Main Methods:
- A study of 150 patients with inducible ventricular tachyarrhythmias undergoing serial electropharmacologic testing.
- Assessed the probability of identifying predicted effective therapy and its success in preventing arrhythmia recurrence.
- Analyzed therapy success as a function of the number of preceding trials.
Main Results:
- The probability of identifying predicted effective therapy was significantly higher with the first trial (23%) compared to subsequent trials (9-5%).
- No effective therapy was identified after the third trial.
- Two-year freedom from sustained ventricular tachyarrhythmias was highest with therapy selected from the first three trials.
Conclusions:
- The probability of selecting effective therapy decreases significantly with each additional electropharmacologic drug trial.
- Electrophysiologic drug testing should be abandoned after three unsuccessful trials.
- This suggests a limited utility of serial testing beyond the initial trials for guiding ventricular tachyarrhythmia therapy.