1. Date of download: 7/10/2016 Copyright © 2016 American Medical Association. All rights reserved. From: Variation in Use of Dual-Chamber Implantable Cardioverter-Defibrillators: Results From the National Cardiovascular Data Registry Arch Intern Med. 2012;172(8):634-641. doi:10.1001/archinternmed.2012.394 Figure 1. Study sample. ICD, implantable cardioverter-defibrillator; NCDR, National Cardiovascular Data Registry; QRS, QRS interval duration. Figure Legend:

2. Date of download: 7/10/2016 Copyright © 2016 American Medical Association. All rights reserved. From: Variation in Use of Dual-Chamber Implantable Cardioverter-Defibrillators: Results From the National Cardiovascular Data Registry Arch Intern Med. 2012;172(8):634-641. doi:10.1001/archinternmed.2012.394 Figure 4. Proportion of patients receiving a dual-chamber implantable cardioverter-defibrillator by hospital referral region. Figure Legend:

3. Date of download: 7/10/2016 Copyright © 2016 American Medical Association. All rights reserved. From: Variation in Use of Dual-Chamber Implantable Cardioverter-Defibrillators: Results From the National Cardiovascular Data Registry Arch Intern Med. 2012;172(8):634-641. doi:10.1001/archinternmed.2012.394 Figure 3. Percentage of primary prevention patients who received a discretionary dual-chamber implantable cardioverter-defibrillator (ICD) by physician. Figure Legend:

4. Date of download: 7/10/2016 Copyright © 2016 American Medical Association. All rights reserved. From: Variation in Use of Dual-Chamber Implantable Cardioverter-Defibrillators: Results From the National Cardiovascular Data Registry Arch Intern Med. 2012;172(8):634-641. doi:10.1001/archinternmed.2012.394 Figure 2. Percentage of primary prevention patients who received a discretionary dual-chamber implantable cardioverter-defibrillator (ICD) by hospital. Figure Legend: