Cardiac arrest or sustained VT (ventricular tachycardia) in patients with heart disease is
best treated with an ICD (implantable cardioverter defibrillator). However, the ICD alone is
not appropriate therapy for patients with frequent VT episodes. In fact frequent shocks for
VT may predict a poorer prognosis. Anti-arrhythmic drugs are co-administered with ICDs in up
to 50% of patients to prevent VT episodes, but antiarrhythmic drugs may have harmful
effects. Thus improved drugs to prevent VT without interfering with ICD function are needed.
Recent data including our own suggest that clonidine may be a new therapy to prevent ICD
shocks. It may act centrally on sympathetic outflow and peripherally and selectively on
cardiac Purkinje, to suppress and control VT occurring in patients. Our purpose is to test
the hypothesis that clonidine reduces frequent VT better than beta blocker in patients with
ICDs. After informed consent patients will be randomized in a single blind fashion to either
clonidine or metoprolol given three times per day. Other prescribed drugs may be adjusted to
promote toleration of the study drug. ICD interrogations of episodes of VT will be the
primary endpoint. Device based NIPS (non-invasive programmed stimulation) testing in a
subset of these patients will allow mechanistic understanding of the clonidine effect. All
of the procedural techniques are in place as performed clinically; preliminary data are
given showing feasibility of the project.
we had wanted very commonly occurring VT episodes on ICD interrogation: 5 episodes/ 3months.
We could not enroll more than 8 patients most of which have interventions to prevent
episodes. Thus we could not enroll patients and discontinued the study in the first year.
- Implantable defibrillator treated patients with 5 episodes of ventricular tachycardia
per 3 month period
- No more than one shock/3 months
- No contraindication to clonidine