EP Show – Aug 2003 ICDs – Secondary prevention The EP Show: Which ICD for which patient? Part 1: Secondary prevention Eric Prystowsky MD Director, Clinical Electrophysiology Laboratory St Vincent Hospital Indianapolis, IN Helmut Klein MD Head of Division of Cardiology Otto-von-Guericke Universität Magdeburg Magdeburg, Germany Paul Dorian MD Professor of Medicine Division of cardiology St. Michael's Hospital Toronto, ON

EP Show – Aug 2003 ICDs – Secondary prevention 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

EP Show – Aug 2003 ICDs – Secondary prevention 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

EP Show – Aug 2003 ICDs – Secondary prevention Clinical trials

EP Show – Aug 2003 ICDs – Secondary prevention 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

EP Show – Aug 2003 ICDs – Secondary prevention Amiodarone? In a debate Stuart Connelly suggested amiodarone is a reasonable alternative for patients with EF >35% 11-year mortality follow-up of CIDS ICD (%) (n=60) Amiodarone (%) (n=60) HR Annual mortality rate (p=0.0231) Dorian P et al. AHA 2002

EP Show – Aug 2003 ICDs – Secondary prevention 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

EP Show – Aug 2003 ICDs – Secondary prevention 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

EP Show – Aug 2003 ICDs – Secondary prevention 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

EP Show – Aug 2003 ICDs – Secondary prevention 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

EP Show – Aug 2003 ICDs – Secondary prevention 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

EP Show – Aug 2003 ICDs – Secondary prevention 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

EP Show – Aug 2003 ICDs – Secondary prevention Long-term mortality Measure ICD (n=60) Amiodarone (n=60) HR Annual mortality rate 4.8%8.4%2.01 (p=0.0231) Total number of deaths 1628NA 11-year mortality follow-up of CIDS Dorian P, et al. AHA 2002

EP Show – Aug 2003 ICDs – Secondary prevention 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

EP Show – Aug 2003 ICDs – Secondary prevention 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

EP Show – Aug 2003 ICDs – Secondary prevention 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

EP Show – Aug 2003 ICDs – Secondary prevention 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

EP Show – Aug 2003 ICDs – Secondary prevention 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

EP Show – Aug 2003 ICDs – Secondary prevention 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

EP Show – Aug 2003 ICDs – Secondary prevention 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

EP Show – Aug 2003 ICDs – Secondary prevention 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

EP Show – Aug 2003 ICDs – Secondary prevention 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

EP Show – Aug 2003 ICDs – Secondary prevention The EP Show: Which ICD for which patient? Part 2: Primary prevention Eric Prystowsky MD Director, Clinical Electrophysiology Laboratory St Vincent Hospital Indianapolis, IN Helmut Klein MD Head of Division of Cardiology Otto-von-Guericke Universität Magdeburg Magdeburg, Germany Paul Dorian MD Professor of Medicine Division of cardiology St. Michael's Hospital Toronto, ON