Characteristics and outcomes of patients receiving new and replacement implantable cardioverter-defibrillators: results from the NCDR

Abstract

Background: Little is known about the clinical features, procedural risks, or survival of patients receiving replacement versus new implantable cardioverter-defibrillators (ICDs).

Methods and results: Entries in the National Cardiovascular Data Registry (NCDR) ICD Registry from 2005 through 2010 were eligible for inclusion (n=463,978). Baseline demographic data, clinical information, and procedural variables were compared between patients receiving new (n=359,993; 77.6%) and replacement (n=103,985; 22.4%) ICDs and entered into a propensity match model to determine adjusted survival rates. Patients receiving replacement ICDs were older (70.7 versus 67.5 years of age) and more likely to have atrial fibrillation (41.8% versus 31.4%; P<0.001) and ventricular tachycardia (60.5% versus 33.9%; P<0.001) compared with patients receiving new ICDs. Median battery life was only 4.6 years (25%-75% interquartile range, 3.7-5.8) for all replaced devices, 5.8 (25%-75% interquartile range, 4.2-7.5) for single-chamber, 5.1 (25%-75% interquartile range, 4.1-6.1) for dual-chamber, and 3.9 (25%-75% interquartile range, 3.2-4.6) years for biventricular devices. Patients receiving replacement ICDs had lower rates of index admission complications (0.9% versus 3.2%; P<0.001) but greater risk for death compared receiving patients receiving new ICDs in unadjusted analysis (hazard ratio, 1.18; 95% confidence interval, 1.16-1.20; P<0.0001) and after propensity-score matching (hazard ratio, 1.28; 95% confidence interval, 1.25-1.30; P<0.0001).

Conclusions: Patients receiving replacement ICDs are older and at greater risk for death compared with those receiving initial ICD implants. The battery life of initial ICDs is shorter than previously reported.

Keywords: death, sudden; defibrillation; implantable cardioverter-defibrillators.

Figures

Figure 1

All patients entered into the ICD Registry from January 2005 – March 2010 were eligible. Those without usable social security numbers and those with multiple entries into the database were also excluded. For those patients receiving replacement ICDs, those whose reason(s) for replacement did not include end of expected battery life were also excluded.

Figure 2

Distribution of time (in years) from initial implant for patients receiving replacement ICDs, divided by original device type (single-chamber, dual-chamber, or biventricular ICD).

Figure 3

Unadjusted KM curve for survival for patients receiving new ICDs (solid line) or replacement ICDs (dotted line).

Figure 4

Hazard ratios for survival for propensity matched patients receiving new and replacement ICDs stratified by device type.