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J Am Coll Cardiol. 2014 Jul 22;64(3):256-64. doi: 10.1016/j.jacc.2014.01.085.

Predictors of an inadequate defibrillation safety margin at ICD implantation: insights from the National Cardiovascular Data Registry.

Author information

1
Cardiac Electrophysiology Section, Division of Cardiology, University of California, San Diego, San Diego, California. Electronic address: jonathan.hsu@ucsd.edu.
2
Section of Cardiac Electrophysiology, Division of Cardiology, University of California, San Francisco, San Francisco, California.
3
Duke Clinical Research Institute, Duke University Medical Center, Durham, North Carolina.
4
Section of Cardiovascular Medicine, Yale University School of Medicine, New Haven, Connecticut.
5
Cardiac Arrhythmia Services, Southcoast Health System, Fall River, Massachusetts.
6
Division of Cardiology, Hartford Hospital, Hartford, Connecticut.
7
Cooper Medical School of Rowan University, Cooper University Hospital, Camden, New Jersey.

Abstract

BACKGROUND:

Defibrillation testing is often performed to establish effective arrhythmia termination, but predictors and consequences of an inadequate defibrillation safety margin (DSM) remain largely unknown.

OBJECTIVES:

The aims of this study were to develop a simple risk score predictive of an inadequate DSM at implantable cardioverter-defibrillator (ICD) implantation and to examine the association of an inadequate DSM with adverse events.

METHODS:

A total of 132,477 ICD Registry implantations between 2010 and 2012 were analyzed. Using logistic regression models, factors most predictive of an inadequate DSM (defined as the lowest successful energy tested <10 J from maximal device output) were identified, and the association of an inadequate DSM with adverse events was evaluated.

RESULTS:

Inadequate DSMs occurred in 12,397 patients (9.4%). A simple risk score composed of 8 easily identifiable variables characterized patients at high and low risk for an inadequate DSM, including (with assigned points) age <70 years (1 point); male sex (1 point); race: black (4 points), Hispanic (2 points), or other (1 point); New York Heart Association functional class III (1 point) or IV (3 points); no ischemic heart disease (2 points); renal dialysis (3 points); secondary prevention indication (1 point); and ICD type: single-chamber (2 points) or biventricular (1 point) device. An inadequate DSM was associated with greater odds of complications (odds ratio: 1.22; 95% confidence interval: 1.09 to 1.37; p = 0.0006), hospital stay >3 days (odds ratio: 1.24; 95% confidence interval: 1.19 to 1.30; p < 0.0001), and in-hospital mortality (odds ratio: 1.96; 95% confidence interval: 1.63 to 2.36; p < 0.0001).

CONCLUSIONS:

A simple risk score identified ICD recipients at risk for an inadequate DSM. An inadequate DSM was associated with an increased risk for in-hospital adverse events.

KEYWORDS:

adverse events; complications; defibrillation safety margin; defibrillation threshold; implantable cardioverter-defibrillator; mortality; national registries; risk score

PMID:
25034061
DOI:
10.1016/j.jacc.2014.01.085
[Indexed for MEDLINE]
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