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Eric Prystowsky MD Director Clinical Electrophysiology Laboratory

The EP show: sudden death, part 1. Eric Prystowsky MD Director Clinical Electrophysiology Laboratory St Vincent Hospital, Indianapolis, IN Douglas P Zipes MD Director, Division of Cardiology and Krannert Institute of Cardiology Indiana University School of Medicine Indianapolis, IN

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Eric Prystowsky MD Director Clinical Electrophysiology Laboratory

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  1. The EP show: sudden death, part 1 • Eric Prystowsky MD • Director • Clinical Electrophysiology Laboratory • St Vincent Hospital, Indianapolis, IN • Douglas P Zipes MD • Director, Division of Cardiology and • Krannert Institute of Cardiology • Indiana University School of Medicine • Indianapolis, IN • Robert J Myerburg MD • Professor of Medicine and Physiology • Director, Division of Cardiology • University of Miami School of Medicine • Miami, FL

  2. Incidence of sudden cardiac death • Since 1970, sudden cardiac death has been estimated to represent about 50% of all cardiovascular deaths, or 300 000 annually. • Although the true incidence is not known, it is now likely to be higher given a greater number of chronic heart disease patients at risk in a growing and aging population.

  3. Risk categories for sudden death • In the adult population, aged 35 and over, the incidence of sudden cardiac death approaches 0.1-0.2% per year or 1 in every 500-1000 individuals. • In the adolescent and adult population below 30, the incidence of sudden cardiac death is approximately 1 in 100 000, and is slightly higher for athletes.

  4. Current intervention strategies for sudden cardiac death • Other than general disease prevention measures applicable to the population at large, intervention strategies focus on patients who are post-myocardial infarction, and who have low ejection fractions and arrhythmic markers of risk. • The highest risk groups have a 10-30% risk per year. Many studies are now concentrating on populations at moderate risk, eg, heart failure patients.

  5. Intervention strategies for the general population • Most noninvasive electrophysiologic markers are not helpful in determining risk in the general population, in patients with multiple risk factors, or in low risk post-MI patients. • Sudden death is the marker for coronary disease in 20-30% of sudden deaths whose etiology is ischemia. • Future noninvasive risk factors may include a profile of inflammatory markers in addition to genetic profiling.

  6. Ischemia and sudden death • It has been well documented that only about 20% of the patients who are resuscitated from ventricular fibrillation (VF) and then hospitalized evolve transmural infarction. • Yet 3/4 of these patients are also found to have coronary artery disease. • Also, autopsy data shows that a significant number of patients who die from VF have severe coronary disease, often with signs of recent plaque disruption.

  7. Precipitants of ventricular fibrillation • The precipitant of VF in those patients who are found not to have an evolving infarction or ischemic markers is unknown. • Several possibilities include coronary vasospasm, and transient thrombotic events in the coronary arteries which produce ischemia but not infarction. • An implantable ischemic sensor device which measures wall motion abnormalities or ST-segment shifts may be useful in this regard.

  8. The evolution of the ambulatory CCU • “But if you stop and think of how we take care of outpatients, it's much like we took care of the infarct 30 years ago. A patient comes and sees you and you write a script for whatever it is and you send the patient home. And he comes back a month or 3 months later, if he's still alive, and then you continue therapy.” • Douglas P Zipes MD • Indiana University School of Medicine • Indianapolis, IN

  9. Multicenter Automatic Defibrillator Implantation Trial • Prophylactic therapy with an implantable cardioverter-defibrillator was compared with conventional medical therapy in a high-risk group of 196 post-MI patients. • Over an average follow-up of 27 months, therapy with the ICD led to improved survival when compared with conventional therapy (hazard ratio for overall mortality, 0.46; 95 percent confidence interval, 0.26 to 0.82; P=0.009). Moss AJ, et al. N Engl J Med 1996;335:1933-1940  

  10. Multicenter Unsustained Tachycardia Trial: protocol Electrophysiologic studies Registry (n=1435) sustained VT not inducible Randomization (n=704) sustained VT inducible Conservative therapy (n=353) ACE-inhibitors and beta-blockers EP-guided therapy (n=351) ACE-inhibitors and beta-blockers Buxton AE, et al. N Engl J Med 1999;341:1882-1890

  11. MUSTT results EP guided therapy showed a reduction in primary endpoints: 27% reduction in arrhythmic death and cardiac arrest trend toward overall reduction in mortality (20% risk reduction) The entire benefit derived from EP-guided therapy was due to treatment with implantable defibrillators. Buxton AE, et al. N Engl J Med 1999;341:1882-1890

  12. Secondary prevention of sudden cardiac death: CASH • The Cardiac Arrest Study, Hamburg • Survivors of cardiac arrest secondaryto documented ventricular arrhythmias wererandomized to an ICD or medical antiarrhythmic therapy (288 patients total). • There was a nonsignificant trend toward higher survival in patients assigned to ICD therapy. Kuck KH, et al. Circulation 2000; 102(7):748-754

  13. Secondary prevention of sudden cardiac death: CIDS • The Canadian Implantable Defibrillator Study • 659 patients with resuscitated VF, ventricular tachycardia (VT), or unmonitored syncope were randomized to ICD or amiodarone therapy. • Nonsignificant relative risk reductions of 20% and 33% were found to occur in all-cause mortality and arrhythmic mortality in the ICD group compared to amiodarone. Connolly SJ, et al. Circulation 2000; 101(11):1297-1302

  14. Secondary prevention of sudden cardiac death: AVID • Antiarrhythmics Versus Implantable Defibrillators study • 1016 survivors of VF or VT were randomly assigned to either ICD or antiarrhythmic-drug therapy. • Over three years, statistically significant relative reductions in mortality from 27-39% were seen in the ICD group. The Antiarrhythmics Versus Implantable Defibrillators (AVID) Investigators. N Engl J Med 1997;337:1576–1583

  15. AVID data and heart failure • Combined data from secondary prevention trials, and AVID data alone, show that patients with ejection fractions above 35% did not receive additional benefit from an ICD compared to amiodarone alone. • The 2 therapies offered have equal outcomes. Domanski MJ, et al. J Am Coll Cardiol 1999;34:1090-1095

  16. AVID data and mortality risk • AVID registry data suggests that there is a high mortality rate for patients with VF and VT thought due to reversible factors, and for patients who manifest only asymptomatic VT. • This mortality rate is similar to the rate for more high-risk ventricular arrhythmias and suggests that clinical judgment regardingreversibility and recurrence risk is not very accurate. Anderson JL, et al. Circulation 1999;99:1692-1699

  17. Persistence of reversibility • Early studies attributing sudden cardiac death to MI relied on the presence of enzymes, new Q waves and a clinical history of pain preceding the onset of cardiac arrest. • New data are highlighting the distinction between reversibility and persistence of reversibility in cardiac arrest survivors. • For example, active plaque pathophysiology in cardiac arrest victims (present in 40-70%) may be reversible, but not permanently reversible.

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