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

1. The EP Show: Which ICD for which patient? Part 1: Secondary prevention Eric Prystowsky MDDirector, Clinical Electrophysiology Laboratory St Vincent Hospital Indianapolis, IN Helmut Klein MD Head of Division of CardiologyOtto-von-Guericke Universität Magdeburg Magdeburg, Germany Paul Dorian MD Professor of Medicine Division of cardiology St. Michael's Hospital Toronto, ON

2. 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

3. 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

4. Clinical trials

5. 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

6. Amiodarone? • In a debate Stuart Connelly suggested amiodarone is a reasonable alternative for patients with EF >35% • 11-year mortality follow-up of CIDS Dorian P et al. AHA 2002

7. 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

8. 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

9. 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

10. 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

11. 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

12. 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

13. Long-term mortality 11-year mortality follow-up of CIDS Dorian P, et al. AHA 2002

14. 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

15. 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

16. 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

17. 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

18. 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

19. 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

20. 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

21. 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

22. 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

23. The EP Show: Which ICD for which patient? Part 2: Primary prevention Eric Prystowsky MDDirector, Clinical Electrophysiology Laboratory St Vincent Hospital Indianapolis, IN Helmut Klein MD Head of Division of CardiologyOtto-von-Guericke Universität Magdeburg Magdeburg, Germany Paul Dorian MD Professor of Medicine Division of cardiology St. Michael's Hospital Toronto, ON