Strategic Programming of Detection and Therapy Parameters in Implantable Cardioverter-Defibrillators Reduces Shocks in Primary Prevention PatientsResults From the PREPARE (Primary Prevention Parameters Evaluation) Study
Bruce L. Wilkoff, MD, FACC*,*,
Brian D. Williamson, MD, FACC ,
Richard S. Stern, MD, FACC ,
Stephen L. Moore, DO, FACC ,
Fei Lu, MD, FACC||,
Sung W. Lee, MD, FACC¶,
Ulrika M. Birgersdotter-Green, MD#,
Mark S. Wathen, MD**,
Isabelle C. Van Gelder, MD,
Brooke M. Heubner, MS,
Mark L. Brown, PhD,
Keith K. Holloman, BA for the PREPARE Study Investigators
* The Cleveland Clinic Foundation, Cleveland, Ohio
William Beaumont Hospital, Troy, Michigan
Doctors Medical Clinic, San Pablo, California
EMH Regional Medical Center, Elyria, Ohio
|| Fairview Regional Medical Center, Minneapolis, Minnesota
¶ Washington Adventist Hospital, Takoma Park, Maryland
# University of California-San Diego, San Diego, California
** Vanderbilt University Medical Center, Nashville, Tennessee
University Medical Center Groningen, University of Groningen, Groningen, the Netherlands
Medtronic, Inc., Minneapolis, Minnesota.
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Figure 1 Programmed ICD Therapies Versus Heart Rate
(A) Cumulative percentage of patients programmed to antitachycardia pacing (ATP) and/or shock therapy (number of patients with ATP or shock therapy on at each heart rate/total number of patients in the cohort). The solid red line illustrates that nearly all PREPARE study patients had their implantable cardioverter-defibrillator (ICD) enabled to treat tachycardias >182 beats/min. In contrast, programming for the control cohort was enabled to treat slower tachycardias for the majority of patients. (B) Cumulative percentage of treated patients programmed to ATP on (number of patients with ATP programmed on at each heart rate/number of patients with ATP or shock therapy programmed on at each heart rate). The solid red line illustrates that nearly all PREPARE study patients who were programmed to be treated were programmed to be treated with ATP up to 250 beats/min. In marked contrast, a large proportion of control patients were programmed to be treated with shock, not ATP. For example, only about 40% of control patients programmed to be treated at heart rates faster than 200 beats/min were treated with ATP, while the remaining 60% were programmed to deliver shock without ATP. Bi-V = biventricular implantable cardioverter-defibrillator; bpm = beats/min.
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Figure 2 Morbidity Index for the PREPARE Study Patients Versus the Control Cohort
The PREPARE study patients had fewer morbidity index events (primary end point) as compared with the control cohort. Both appropriate and inappropriate shocks were substantially reduced in the PREPARE study programmed patients. There were relatively few syncopal events that contributed to the primary end point. SVT = supraventricular tachycardia or other nonventricular tachycardia or ventricular fibrillation event; VF = ventricular fibrillation; VT = ventricular tachycardia.
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Figure 3 Time to First Shock by Study Cohort
Kaplan-Meier curves show the percentage of patients (Pts) in each study cohort receiving a first shock during the first 12 months of follow-up due to: (A) all-cause; (B) true VT/VF; (C) true SVT/other. For each case, the p value reports the results of a log-rank test comparing the PREPARE study cohort and control cohort curves. Abbreviations as in Figure 2.
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Figure 4 Patient Mortality by Study Cohort
Kaplan-Meier curves show the mortality rate in patients (Pts) from each study cohort during the first 12 months of follow-up. The p value reports the results of a log-rank test comparing the PREPARE study cohort and control cohort curves.
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