The EP Show: Which ICD for which patient? Part 1: Secondary prevention

EP Show – Aug 2003

ICDs – Secondary prevention

The EP Show: Which ICD for which patient? Part 1: Secondary preventionEric Prystowsky MD

Director, Clinical Electrophysiology Laboratory St Vincent Hospital

Indianapolis, IN

Helmut Klein MD Head of Division of CardiologyOtto-von-Guericke Universität MagdeburgMagdeburg, Germany

Paul Dorian MD Professor of MedicineDivision of cardiologySt. Michael's HospitalToronto, ON



Secondary prevention

Secondary prevention patients

•Documented history of cardiac arrest due to ventricular abnormality

•Documented sustained ventricular

tachycardia with symptoms requiring intervention

•Syncope due to a ventricular arrhythmia

Dorian



Patients at risk

Any patient with a sustained life-threatening arrhythmia without reversible cause is at very high risk without treatment

Prognosis of patients with sustained ventricular tachycardia in the presence of heart disease is as bad as for those with a history of cardiac arrest

Dorian



Clinical trials

0

5

10

15

20

25

30

35

40

45

All-c

ause m

ort

ality

(%

)

AVID CIDS CASH

Medical therapy ICD



Consensus

Consensus has been reached that someone who is at high risk of sudden cardiac death is best treated by an ICD

•Questions remain about how to treat a patient suffering cardiac arrest in the context of another severe illness

Dorian



Amiodarone?

In a debate Stuart Connelly suggested amiodarone is a reasonable alternative for patients with EF >35%

11-year mortality follow-up of CIDSICD (%) (n=60)

Amiodarone (%) (n=60) HR

Annual mortality

rate

4.8 8.4 2.01 (p=0.0231)

Dorian P et al. AHA 2002



Two questions

What is the role of amiodarone in Europe?

Are we really able to determine what is and isn't reversible cause?

"Maybe we're not so smart in picking up reversible causes."

Prystowsky



Amiodarone in Europe

Amiodarone in patients with better EF:

•Was originally thought the ideal ICD candidate would have better EF

• Reality is that incidence of sudden death

is much higher in patients with low EF, and ICDs are much more effective there

Europe is coming over to the idea of ICDs as the main approach

Klein



Ventricular function changes

"You never know when the ventricular performance changes and gets worse. Impaired ventricular function is not a

sign that starts with one symptom and then you know."

A patient can have a small ischemic event without noticing and suddenly drop in ejection fraction

Klein



ICDs first

Patients who have had a cardiac arrest, regardless of reason, need an ICD

Amiodarone can be used as additional therapy or for those who may have recurring sustained ventricular tachycardia to limit ventricular intervention

Klein



Follow-up

A major limitation of the the major ICD trials is that follow-up was only two to three years but the disease is a chronic one

"The severity of the underlying heart disease is a moving target,

and the sad reality is that the trajectory of the severity of heart disease is such that most patients over the long term will get worse."

Dorian



ICDs over time

The trials don't tell us, but the probability of benefiting from an ICD will increase over time

Improvements in heart-failure therapy mean most patients receiving ICDs for secondary prevention do live five years or more

Dorian



Long-term mortality

MeasureICD

(n=60)Amiodarone

(n=60) HRAnnual

mortality rate

4.8% 8.4% 2.01 (p=0.0231)

Total number of deaths

16 28 NA

11-year mortality follow-up of CIDS

Dorian P, et al. AHA 2002



Reversible cause

There are still some reversible causes that are undisputed and are acceptably called "reversible cause":

• A patient comes in with clearly identifiable AMI and has VF in the first 6 to 24 hours is a true reversible cause

• For a hyperkalemia patient, is a K of 2.9 reversible?

Prystowsky



Hypokalemia

During cardiac arrest potassium is taken up inside cells, and so the initial potassium measurement in most patients will be low

"It's probably better to think of hypokalemia as a trigger, rather

than as a cause, of the cardiac arrest."

Dorian



Potassium

If it is truly hypokalemia you ought to repeat the measurement six to eight hours later

•If K is now 4.0 with minimal repletion of potassium then patient needs an ICD

•If K is still in the mid- to high-2 range six to eight hours later then they probably really do have hypokalemia

Prystowsky



Single or dual chamber?

We accept you must be careful what you call reversible, and ICDs are the treatment of choice

• Do we use single or dual chambers, and have the data from DAVID changed your approach?

Prystowsky



Unnecessary pacing

"Continuously pacing means that you create an asynchronous ventricular contraction."

Avoiding pacing when possible is better than just sensing the atrium and pacing the right ventricle continuously

If there is compelling reason such as sinus-node dysfunction then dual-chamber pacing could be used

Klein



Single- or dual-chamber ICD?

"We changed our mind just recently because of the DAVID trial."

Klein

Proportion of single- and dual-chamber pacing?

•Klein: 80% single/20% dual

•Dorian: 30% to 40% single/60% to 70% dual



Dual-chamber ICDs

Dual-chamber ICDs offer the ability to discriminate between supraventricular tachycardia and tachycardia

Programmed for minimum pacing: backup rate <50 beats/minute and

longest AV delay possible

"That allows us to then derive the benefit for the atrial signal for discrimination without the cost of the unwanted ventricular pacing."

Dorian



Minimize pacing

Must minimize the amount of time pacing the ventricle, don't pace unless you have to

• Decision on single vs dual chamber will depend on the individual implanter and the particular patient

"How you actually select who gets the atrial lead will depend on your own philosophy."

Prystowsky



Economics

With less economic pressure, I lean toward using a dual-chamber ICD with minimal programming

"I would be the first to admit to you that if someone shut me down economically for any reason, that I could either get two defibrillators or one with dual-chamber capability, I'd take two defibrillators."

Prystowsky



The EP Show: Which ICD for which patient? Part 2: Primary preventionEric Prystowsky MD

Director, Clinical Electrophysiology Laboratory St Vincent Hospital

Indianapolis, IN

Helmut Klein MD Head of Division of CardiologyOtto-von-Guericke Universität MagdeburgMagdeburg, Germany

Paul Dorian MD Professor of MedicineDivision of cardiologySt. Michael's HospitalToronto, ON

The EP Show: Which ICD for which patient? Part 1: Secondary prevention

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