Transcript Device and Antiarrhythmic Drugs: Advantages and Pitfalls Teresa Menendez Hood, M.D. Implantable cardioverter defibrillators (ICDs) and antiarrhythmic drugs (AAD) • ICDs have been proven successful.

Device and
Antiarrhythmic Drugs:
Advantages and Pitfalls
Teresa Menendez Hood, M.D.
Implantable cardioverter defibrillators
(ICDs) and antiarrhythmic drugs (AAD)
• ICDs have been proven successful in
treating life-threatening ventricular
arrhythmias
• Antiarrhythmic drug therapy now has a
palliative role in the treatment of
ventricular arrhythmias
• The use of both results in beneficial and
adverse interactions
Trends of AAD use in patients
with ICDs
• Decrease in use of AAD in patients with ICDs over
the last 10 years
– The largest decrease has been in Class 1 agents while the
Class 3 agents have actually increased (amiodarone and
sotalol)
• Currently, about 20% - 40% of patients with an ICD
are also on an AAD
– The most common reason that a patient gets put on an AAD
is frequent ICD shocks
• More of a decline in AAD is seen in patients with
cardiac arrest and syncope than in patients with
sustained VT
• Amiodarone is the most common AAD used with
ICDs
Beneficial Effects of AAD + ICD
• Suppression of Recurrent Arrhythmias
– Reduce shocks
– Treat SVT (usually AFIB) that can cause
inappropriate shocks
– Prevent early battery depletion
– May allow antitachycardia pacing (ATP) to
be effective by increasing VTCL (slowing
the VT) and thus avoid shocks
– Prevent hospital readmission for shocks
Beneficial Effects of AAD + ICD
• Prevention of Psychological Effects of ICD shocks
– Patients who receive more shocks have more psychological
distress, decline in physical activity and mental well being
• Helpful in Managing Electrical Storm (ES)
– ES is 2 or more episodes of VT/VF within a 24 hour period
that requires a shock
– 1/3 of patients with an ICD will have ES at some point
– Look for precipitating factors: ischemia, worsening cardiac
function, electrolyte imbalance, autonomic imbalance,
proarrhythmia
• Treat with BB and IV amiodarone
Effectiveness of AAD in
Preventing ICD Shocks due to
VT
• Sotalol have been shown to prolong delivery
of ICD shocks versus placebo in multiple
published studies
• Beta Blockers have been shown to be
beneficial
• Amiodarone has been shown to be beneficial
• Due to the fact that most patients with an ICD have CAD
and CHF, other AAD have not been studied due to the
well known proarrhythmic interaction of Class 1 AAD in
this patient population
Adverse Effects of AAD + ICD
• Increase in the Defibrillation Threshold (DFT)
– DFT: the lowest delivered energy that will convert
VF to NSR
• Tested at implant and must be at least 10 joules below
where you set the first shock
• If it rises too much, then the energy delivered will not
convert the patient out of VF
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Class 1A (Quinidine/Proc/Diso) - +/- DFT
Class 1B (Mexiletine) - increases DFT
Class 1C (Flecanide, Propafenone) - +/- DFT
Class 3 Amio – increases DFT
Class 3 Sotalol – decreases the DFT
Class 2 and 4 have no effect
Adverse Effects of AAD + ICD
• Increase in Pacing Threshold
– All ICDs provide pacing for the treatment
of bradyarrhythmias and for
antitachycardia pacing for VT
– Class 1- all increase the pacing threshold,
especially the Class 1C (use-dependent
block)
– Class 3 amiodarone –may increase the
pacing threshold
Adverse Effects of AAD + ICD
• Prevention of VT detection
– The VT slows , but could be below the rate
cutoff that has been programmed and
does not get treated by the device
• Proarrhythmic Effects
– lead to more frequent or malignant
arrhythmias that require an increase in ICD
intervention
Negative Effects
• Heart rate is too slow and results in pause
dependent PMVT
– if programmed at a slow pacing rate and usually
this is VVI and need to upgrade to a DDD device
and pace at a faster rate
• Conversion of AFB to AFL with 1:1
conduction (usually with 1C drugs)
– May go from rates of 120-130 to >200 and fall into
the VT zone
• Make sure that the SVT discriminators (only if have an
atrial lead) are on such as :
– V:A relation, stability, onset and wavelet morphology (QRS
width)
Proarrhythmic Effects
• Prolongation of the QT may lead to
oversensing of the T wave and double counting
with inappropriate shocks
– This is not uncommon in dialysis patients
• Slowing of the sinus rate or the AV node may
lead to an increase in RV pacing which may
lead to battery depletion, VVI pacing with
pacemaker syndrome or forced RV pacing with
worsening of LV synchrony and worsening of
CHF
Summary
• ICDs are the treatment of choice for primary
and secondary prevention of lethal
ventricular arrhythmias
• At least 1/3 will require adjuvant AAD therapy
• Class 3 agents appear to be the best
tolerated drugs in this patient population
• This hybrid therapy has potential pitfalls that
need to be recognized and may require
reprogramming of the ICD for patient safety