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Selecting therapy for sustained ventricular tachycardias: importance of the sensitivity and specificity of programmed
W G Stevenson1, J Weiss, R K Oye
1Division of Cardiology, UCLA Medical Center.
Abstract:
Antiarrhythmic therapy for prevention of sustained ventricular tachycardia is commonly guided by programmed electrical stimulation, and the persistent ability to initiate ventricular tachycardia during drug therapy often leads to the use of nonpharmacologic therapies such as surgery. Prior studies suggest that programmed stimulation has a high sensitivity but a lower specificity for predicting recurrences of ventricular tachycardia during drug therapy. We constructed a model to evaluate the impact of various programmed stimulation specificities and sensitivities on total mortality when patients with inducible ventricular tachycardia during drug therapy proceed to arrhythmia surgery. Assumptions for this model included an 11.5% surgical mortality, a 13% risk of arrhythmia recurrence for surgery survivors, and that 33% of ventricular tachycardia recurrences are fatal. In this model the relative impact of test sensitivity and specificity on total population mortality depended on the pretest probability that drug therapy would be effective. When this probability was high, variations in test sensitivity had relatively little impact on mortality, but a low specificity increased mortality by increasing the number of false positive patients treated surgically who then suffered the surgical mortality. When the probability of effective drug therapy was low, varying test specificity had relatively little impact on mortality, but a low sensitivity increased mortality by increasing the number of patients with a false negative test who suffered fatal arrhythmia recurrences. If the specificity of programmed stimulation is low and the probability that drug therapy will be effective is high, the total population mortality can exceed the mortality expected from drug therapy alone.(ABSTRACT TRUNCATED AT 250 WORDS)
Insights
Programmed electrical stimulation guides antiarrhythmic therapy for ventricular tachycardia. Poor test specificity can increase mortality when drug therapy is likely effective, while low sensitivity increases mortality when drug therapy is unlikely effective.
Area of Science:
- Cardiology
- Medical Modeling
- Electrophysiology
Background:
- Antiarrhythmic drug therapy for sustained ventricular tachycardia (VT) is often guided by programmed electrical stimulation (PES).
- Failure to suppress VT during PES may lead to non-pharmacologic interventions like surgery.
- Prior research indicates PES has high sensitivity but lower specificity for predicting VT recurrence during drug therapy.
Purpose of the Study:
- To model the impact of PES sensitivity and specificity on total mortality.
- To evaluate outcomes for patients with inducible VT undergoing surgery after drug therapy.
- To analyze how pretest probability of effective drug therapy influences mortality predictions.
Main Methods:
- A mathematical model was constructed to simulate patient outcomes.
- Assumptions included surgical mortality (11.5%), recurrence risk (13%), and fatality of recurrence (33%).
- The model assessed the interplay between PES test characteristics and pretest probability of drug efficacy.
Main Results:
- The impact of PES sensitivity and specificity on mortality is dependent on the pretest probability of effective drug therapy.
- When drug therapy is likely effective, low specificity increases mortality due to unnecessary surgeries.
- When drug therapy is unlikely effective, low sensitivity increases mortality due to fatal VT recurrences in false-negative patients.
Conclusions:
- PES test characteristics significantly influence mortality predictions for VT patients.
- Low specificity of PES can lead to excess mortality when drug therapy is likely effective.
- Low sensitivity of PES can lead to excess mortality when drug therapy is unlikely effective.