Inappropriate Implantable Cardioverter-Defibrillator Shocks in MADIT IIFrequency, Mechanisms, Predictors, and Survival Impact
James P. Daubert, MD*,*,
Wojciech Zareba, MD, PhD*,
David S. Cannom, MD ,
Scott McNitt, MS*,
Spencer Z. Rosero, MD*,
Paul Wang, MD ,
Claudio Schuger, MD ,
Jonathan S. Steinberg, MD||,
Steven L. Higgins, MD¶,
David J. Wilber, MD#,
Helmut Klein, MD**,
Mark L. Andrews, BBA*,
W. Jackson Hall, PhD,
Arthur J. Moss, MD* for the MADIT II Investigators
* Cardiology Division, Department of Medicine, University of Rochester Medical Center, Rochester, New York
Good Samaritan Hospital, Los Angeles, California
Stanford University Medical Center, Stanford, California
Henry Ford Health System, Detroit, Michigan
|| St. Luke’s-Roosevelt Hospital Center, New York, New York
¶ Scripps Memorial Hospital, La Jolla, California
# Loyola University Medical Center, Maywood, Illinois
** University Hospital, Magdeburg, Germany
Department of Biostatistics, University of Rochester Medical Center, Rochester, New York.
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Figure 1 Survival Free of Inappropriate Shock/Therapy
(A) The cumulative proportion of patients who experienced a first inappropriate shock (due to any mechanism) is plotted versus time. (B) The cumulative proportion of patients who experienced a first inappropriate therapy, antitachycardia pacing (ATP) or shock (due to any mechanism) is plotted versus time. The number of patients at risk at a given time point of follow-up is indicated below the x axis. The proportion of the population experiencing the event in question is given in parentheses at the 1-, 2-, and 3-year time points.
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Figure 2 Time-Dependent Occurrence of Inappropriate Shock by Type
The cumulative proportion of patients experiencing a first inappropriate (Inapp.) shock due to the 3 subcategories of inappropriate shock is plotted with respect to time. The number of patients at risk at a given time point of follow-up is indicated below the x axis. The proportion of the population experiencing the event in question is given in parentheses at the 1-, 2-, and 3-year time points. AF = atrial fibrillation or atrial flutter; ICD = implantable cardioverter-defibrillator; SVT = supraventricular tachycardia.
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Figure 3 Ventricular Rate Precipitating Inappropriate Shock
The heart rate at the time of the ICD detection resulting in a patient’s first inappropriate shock is shown in the bar graph in groups of 10 beats/min. Atrial fibrillation episodes are shown with cross-hatched bars, and SVT episodes are shown with solid bars. Inappropriate shocks caused by abnormal sensing are excluded because the device has by definition misconstrued the actual ventricular rate (typically normal in these cases). The events relate to shocks, not patients, in this figure. Abbreviations as in figure 2.
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