Use of Dual-Chamber Implantable Cardioverter-Defibrillators Varies

The use of dual-chamber implantable cardioverter-defibrillators (ICDs) to prevent sudden death in patients without an indication for permanent pacing varies widely by region and hospital, according to the results of a cross-sectional study. Researchers reported the findings in Archives of Internal Medicine [2012;172(8):634-641].

It is well established that ICDs reduce mortality risk among patients with heart failure and left ventricular systolic dysfunction. As a result, the Centers for Medicare & Medicaid Services (CMS) covers ICDs for the primary prevention of sudden cardiac death in selected patients, according to the study’s authors. However, they explained, most clinical trials have been performed with single-lead ICD devices, and CMS requires clinicians to justify the medical necessity of ICD devices other than single-lead devices in order to obtain coverage.

The authors noted that some patients have a clear indication for a dual-chamber ICD, which has a lead in the right atrium and right ventricle. These include patients who require pacing for bradyarrhythmias, such as those with heart block or symptomatic sinus node dysfunction. Nevertheless, the authors cited one study that reported among US patients undergoing ICD implantation and not receiving biventricular ICD, nearly two thirds received dual-chamber devices.

While dual-chamber devices are sometimes used in patients who do not have an indication for pacing, the roles that factors such as geographic location and patient characteristics, as well as provider, hospital, or regional factors play in deciding between ICD types have not been well characterized. Consequently, the authors studied variations in dual-chamber ICD use at the hospital and regional level, and also attempted to identify patient and physician factors associated with the use of dual-chamber ICDs.

The analysis was based on data from the NCDR^® (National Cardiovascular Data Registry) ICD Registry™. Participation in the registry is mandated by CMS for Medicare reimbursement for all primary prevention ICDs. In their analysis, the investigators captured data on all patients receiving an ICD for primary prevention from 2006 to 2009. Patients receiving ICDs for secondary prevention were excluded.

Hospitals were divided by regions defined by the US Census (New England, Mid-Atlantic, South Atlantic, Northeast Central, Southeast Central, Northwest Central, Southwest Central, Mountain, and Pacific). Other captured variables included patient data (demographic and clinical), healthcare providers, and hospital characteristics.

Overall, the analysis captured 239,113 first-time primary prevention ICDs. After excluding patients who had an indication for a dual-chamber ICD or who received the device at a low-volume hospital, the eligible population included 87,115 participants.

The investigators reported that dual-chamber devices were used in 58% of patients without pacing indications in 1293 hospitals. In addition, the proportion of dual-chamber devices used rose steadily over the study period, from 53% in the first quarter of 2006 to 62% in the fourth quarter of 2009.

Hospitals demonstrated variable degrees of dual-chamber device use. Specifically, 33 (3%) hospitals exclusively implanted single-chamber ICDs, 109 (8%) exclusively implanted dual-chamber ICDs, and 89% implanted both types. In addition, 11% of physicians exclusively implanted single-chamber ICDs, 23% of physicians exclusively implanted dual-chamber ICDs, and other physicians during the study period implanted both types to varying degrees.

The geographic region with the lowest rate of dual-chamber ICD use was New England, and the region with the highest use was the Pacific. However, no clear pattern was evident overall, with high-use regions immediately adjacent to low-use regions.

After a multivariate logistic regression analysis, patient factors associated with receiving a dual-chamber ICD included older age, diagnosis of atrial fibrillation or flutter, hypertension, and implantation performed by a surgeon. Patients less likely to receive a dual-chamber ICD included those who were African American, receiving hemodialysis, or receiving care through an academic medical center or community hospital.

The authors concluded that regional differences and clustering of use within hospitals were most strongly associated with dual-chamber ICD use, with factors such as patient, healthcare provider, and hospital characteristics having a less important effect.

Study limitations included use of self-reported data, the decision to implant an ICD could be based on clinical factors not captured in the registry, and patient preferences could have played a role that was not captured.