Implantation Trends and Patient Profiles for Pacemakers and Implantable Cardioverter Defibrillators in the United States: 1993–2006

Steven M. Kurtz, Ph.D.; Jorge A. Ochoa, Ph.D.; Edmund Lau, M.S.; Yakov Shkolnikov, Ph.D.; Behzad B. Pavri, M.D.; Daniel Frisch, M.D.; Arnold J. Greenspon, M.D.

Disclosures

Pacing Clin Electrophysiol. 2010;33(6):705-711. 

In This Article

Results

From 1993 to 2006, 481,976 sample records of primary PM implantation were identified, which corresponds to 2.4 million (95% confidence interval [CI]: 2.28–2.50 million) patients with primary PM nationwide. During the same period, 162,300 sample records of primary ICD implantations were identified, which reflects 0.80 million (95% CI: 0.73–0.87 million) patients nationwide who received an ICD. The estimated PM replacement and ICD revision replacement procedures during the same period were 369,000 (95% CI: 344,000–393,000) and 74,000 (95% CI: 63,000–84,000), respectively. Women represented 49.1% (95% CI: 48.9–49.3%) of PM and 23.6% (95% CI: 23.4–23.9%) of ICD patients, respectively. By 2006, ICDs represented 41.5% of all new implantations. The rate of operations per 100,000 persons of population increased significantly for index procedures for both PM and ICD (Fig. 1). The primary PM implantation rate was 50.0 in 1993, peaked at 70.5 in 2001, and declined to 65.1 in 2006. Adjusting for differences among age, sex, race, census regions, and normalized by their corresponding populations, the regression results showed a significant average year-to-year increase of 1.71% in implantation rate (95% CI: 1.55–1.87, P < 0.001). The ICD implantation rate increased rapidly, especially after 2001 (Fig. 1). During the study period, the primary ICD implantation rate increased from 6.1 in 1993 to 46.2 by 2006. The average rate of increase was 17.9% per year (95% CI: 17.6–18.3%, P < 0.001). The PM replacement rate was stable during the study period averaging 9.4 per 100,000 in population and ranged from 7.1 to 11.8 during the study period (P = 0.35). The corresponding ICD replacement rate did show an increase from 1.7 in 1993 to 2.5 in 2006. The estimated year-to-year increase by Poisson regression was significant at 4.0% (95% CI: 0.75–4.6%, P < 0.001).

Figure 1.

The rate of operations per 100,000 persons of population for pacemakers and implantable cardioverter defibrillators in primary procedures and replacements.

The mean age of primary and replacement PM patients was 75.5 (±12.1) years and 73.6 (±16.0), respectively, and remained unchanged though the evaluation period. Overall, the age of ICD recipients was considerably younger with a mean age among primary ICD patients of 66.2 (±12.8) years and a mean patient age of 67.9 (±13.2) years at device replacement. However, during the course of the study period the age at the time of ICD procedures continued to increase. In 1993, the mean age at the time of primary ICD implantation was 63.5 years, which increased to 66.4 years by 2006. During the same time period, age increased from 66.3 to 69.2 years among patients undergoing ICD replacement. The increase of 0.2–0.3 years of age per year is significant (P < 0.0001) for ICD patients undergoing either procedure.

ICD patients presented with significantly more comorbidities than PM patients as assessed by the CCI. Over the study time period, 30.5% and 4.7% of primary ICD patients had a CCI score above 2 and above 4, respectively. By comparison, only 21.5% (≥2) and 3.1% (≥4) of primary PM patients had such levels of comorbidity. Revision procedures also showed a similar difference with 44.9% of ICD patients having no significant comorbidity (CCI = 0) and 55.5% of PM patient having a CCI score of 0. These differences in proportions were statistically significant (P < 0.0001). Longitudinally, the patient health profile, as quantified by the CCI for the PM and ICD patients, showed an increased level of comorbidity over time. ICD patients showed a more rapid increase as compared with PM patients (Fig. 2). Additionally, patients undergoing a primary implantation procedure generally had greater comorbidity than replacement patients.

Figure 2.

Patient health profile as reflected by the Charlson Comorbidity Index of patients undergoing pacemaker or implantable cardioverter defibrillator implantation.

With the understanding that device implantation often occurs when patients are hospitalized for other reasons, we analyzed the length of stay (LOS) for each type of device procedure. The mean LOS for primary ICD procedures decreased significantly (P < 0.0001) over the study timeframe from 16.4 (±13.3) days in 1993 to 5.1 (±7.2) in 2006. Replacement ICD procedures required a much shorter LOS in general but still showed a reduction over the same time frame (5.2 ± 6.6 in 1993 and 3.5 ± 4.4 in 2006). In contrast, the mean patient LOS for replacement PM procedures stayed constant (5.3 ± 7.8 in 1993 and 5.2 ± 7.9 in 2006) while LOS associated with primary PM implantation showed a modest reduction (8.5 ± 10.8 in 1993 and 5.8 ± 7.5 in 2006).

Survival of patients following primary PM surgeries while still hospitalized showed a dramatic improvement over the study period. In 1993, 1.93% of primary PM patients did not survive whereas by 2006, in-hospital mortality rate dropped to 1.15%. ICD implantation was associated with a consistently lower mortality rate of 0.66% in 2006, nearly half that of the 1.15% rate for PM implantation (odds ratio = 0.56, P < 0.001). Mortality rate following replacement surgery was comparable with the respective primary procedures for both types of devices. In our analysis, the mortality rate for PM replacement was 1.26% in 2006 compared with 1.15% among primary implantations in the same year.

Finally, the mean ICD replacement burden was 8.4% (range 5–22%) and decreased significantly over time (P < 0.0001) while the annual replacement burden for PMs remained relatively constant (mean = 13.4%, range 11–16%). The mean replacement burden for PMs was significantly higher than that of ICDs (13.4 vs 8.4%, P < 0.001) (Fig. 3).

Figure 3.

Overall replacement burden for pacemaker and implantable cardioverter defibrillator patients.

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