Clinical Impact of EP Device Infections

Abstract & Commentary

By John P. DiMarco, MD, PhD, Professor of Medicine, Division of Cardiology, University of Virginia, Charlottesville. Dr. DiMarco does research for Medtronic, is a consultant for Medtronic, Novartis, and St. Jude, and is a speaker for Boston Scientific.

Source: Sohail MR, et al. Mortality and cost associated with cardiovascular implantable electronic device infections. Arch Intern Med 2011; Sept 12. [Epub ahead of print]

This paper describes the mortality and economic costs of infections associated with pacemakers and implantable defibrillators (ICDs) in Medicare recipients. The authors analyzed Medicare administrative data for inpatient admissions that involved implantation, replacement, removal, or revision of a pacemaker, an ICD, and cardiac resynchronization therapy pacemakers (CRT-P) and ICDs (CRT-D). Patients who also underwent other major cardiac procedures on the same admission were excluded. Procedures performed solely on an outpatient basis were also excluded. Four primary endpoints were assessed: admission mortality, intermediate term (current plus subsequent four quarters) mortality, admission length of stay (LOS), and admission cost. Endpoints were adjusted for age, gender, race, and 28 additional comorbidity measures. Costs were normalized using Medicare Inpatient Prospective Payment System rates.

Out of a total of 200,219 device-related Medicare admissions, there were 5817 (2.9%) that involved a device infection. Adjusted admission mortality ratios (mortality with vs without infection) for specific device types were 5.9 for pacemakers, 6.4 for ICDs, 4.8 for CRT-D devices, and 7.7 for CRT-P devices. Intermediate-term adjusted mortality ratios were also higher: 2.1 for pacemakers, 1.6 for ICDs, and 1.6 for CRT-D devices. The adjusted increments in intermediate-term total mortality ranged from 8.7% to 15.2%. The standardized adjusted total and incremental LOS were 15.5 and 9.4 days for pacemakers, 18.8 and 12.7 days for ICDs, 17.1 and 11.8 days for CRT-D devices, and 24.3 and 18.2 days for CRT-P devices.

Most admissions analyzed involved only one device implant, whether an infection occurred, and, therefore, there was usually only one device cost per patient. Despite this, infection raised the cost of the admission by 1.4-1.8 fold. Adjusted incremental costs with infection were $16,208 for pacemakers, $14,360 for CRT-P devices, $15,893 for ICDs, and $16,498 for CRT-D systems. Intensive care and pharmacy costs accounted for most of the added expense with infection.

The authors concluded that pacemaker and ICD infections are associated with significant increases in admission, intermediate-term mortality, and hospital costs. They recommended that physicians managing these patients consider different management strategies (e.g., earlier device removal) that might shorten intensive care and overall LOS and reduce costs. The increased admission mortality is understandable due to the complications related to the infection, but the incremental increases in mortality after discharge require further study.

Commentary

Standard and resynchronization pacemakers and ICDs, commonly grouped together as cardiac implantable electrical devices (CIEDs), are now used in millions of patients in the United States and throughout the world. The functionality and component reliability of CIEDs has improved dramatically in the last 20 years. CIED infection, however, remains a dreaded complication of device therapy and the absolute incidence of and the individual risk for a CIED infection appears to be increasing.

With the exception of minor wound infection in which the pocket is not directly involved, the recommended approach to most CIED infections is total removal of all involved hardware. With newly implanted (< 6 months post implant) systems, this is a relatively straightforward procedure that most implanting physicians can carry out. However, if any part of the system has been in place for a longer time, extraction can become more difficult and specialized training, facilities, and techniques are required. As CIED recipients live longer and undergo multiple repeat procedures for replacements and upgrades, the number of infections is sure to continue to rise. This paper, which reviews recent Medicare administrative data, highlights the clinical and economic importance of improving our approach to CIED infection. The authors clearly show that CIED infection substantially increases short- and intermediate-term mortality and results in a substantial total economic burden. The primary emphasis should be to prevent infection, but new strategies to identify infections early, stabilize patients quickly, and reestablish needed long-term treatment after the infection is cleared will also be important.

Although not specifically discussed by the authors in this paper, the reader should also note that intermediate-term mortality after any CIED procedure was quite high even in the absence of infection. Adjusted mortality rates during the index and four subsequent quarters ranged from 17.8% to 20.1%. These data suggest that CIEDs are often used in near end-of-life situations. Reducing inappropriate device prescriptions for patients with little prospect for an improved, meaningful survival would also be economically beneficial.