| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
(Circulation. 1995;91:1063-1069.)
© 1995 American Heart Association, Inc.
Articles |
Permanent Pacemaker Selection and Subsequent Survival in Elderly Medicare Pacemaker Recipients
From the Division of Cardiology, Mount Sinai Medical Center, Miami Beach, and the University of Miami School of Medicine (G.A.L.), Miami, Fla; Cardiovascular Division (G.A.L.), Brigham and Women's Hospital, and the Department of Health Care Policy (C.L.P., S.T.N., B.M.), Harvard Medical School, Boston, Mass.
Correspondence to Gervasio A. Lamas, MD, Chief, Division of Cardiology, Mount Sinai Medical Center, 4300 Alton Rd, Miami Beach, FL 33140.
 |
Abstract |
|---|
 Top Abstract IntroductionMethods Results Discussion References |
|---|
Background Dual-chamber pacemakers have been in use for more than 15 years. Although they may confer a physiological advantage over single-chamber ventricular pacemakers, they are more expensive and have a generally shorter service life than single-chamber devices. We carried out the present study to identify patient subgroups who were preferentially receiving greater or lesser proportions of dual-chamber devices and to determine whether the selection of different types of pacemakers was associated with differences in mortality.
Methods and Results We analyzed a 20% random national sample of all Medicare beneficiaries aged 65 years or older who underwent initial placement of a permanent pacemaker and were discharged in 1988, 1989, or 1990 (n=36 312). The minimum follow-up for vital status was 1 year. The relation of pacemaker type to patient and provider characteristics was determined using logistic regression analysis. The relation between pacemaker type and mortality was determined using the Cox proportional hazards method. The proportion of dual-chamber systems that were received increased from 27.2% in 1988 to 37.0% in 1990 (P<.001). Dual-chamber pacemaker recipients were younger (P<.001) than ventricular pacemaker recipients. Other independent correlates of dual-chamber pacemaker selection included male sex (odds ratio and 95% confidence intervals, 1.18 and 1.12 to 1.24, respectively), atrioventricular block (1.59 and 1.51 to 1.67), congestive heart failure (1.14 and 1.08 to 1.20), atrial fibrillation (0.36 and 0.34 to 0.39), and the presence of a major noncardiac diagnosis (0.86 and 0.83 to 0.89). Nonmedical predictors of dual-chamber pacemaker selection included Medicaid eligibility (0.78 and 0.71 to 0.86), implantation in the western United States (1.19 and 1.10 to 1.29), implantation by a rural provider (0.70 and 0.65 to 0.76), hospitalization in a 500-bed-or-larger hospital (1.20 and 1.13 to 1.28), hospitalization in a private hospital (1.19 and 1.10 to 1.28), or hospitalization in a hospital with a catheterization laboratory (1.47 and 1.38 to 1.56). Dual-chamber pacemaker selection was an independent predictor of survival at 1 year (0.82 and 0.77 to 0.87) and at 2 years (0.82 and 0.77 to 0.87) after controlling for potentially confounding patient-level and hospital-level characteristics.
Conclusions The present study describes important variations in the clinical practice of cardiac pacing, many of which are not based on clinical characteristics. Furthermore, the selection of a dual-chamber pacemaker is associated with increased survival. These results underscore the need for prospective, outcome-based clinical trials of pacemaker mode selection.
Key Words: pacing • mortality • pacemakers
|
Introduction |
|---|
|
TopAbstractIntroductionMethods Results Discussion References |
|---|
Permanent pacemakers are implanted to prevent or treat bradycardia caused by disorders of the cardiac conduction system.1 For more than 15 years, there have been two broad types of pacing systems: single chamber (ventricular) and dual chamber. The selection of either a single- or a dual-chamber pacemaker has clinical and economic implications. Specifically, the known physiological2 3 and suspected clinical benefits4 5 6 of dual-chamber pacing may be offset by the increased cost and decreased service life of these devices compared with single-chamber pacemakers.3 8 The purpose of this study was to analyze a large national administrative database to identify patient subgroups who were preferentially receiving greater or lesser proportions of single- or dual-chamber devices. Furthermore, we sought to determine whether the selection of different types of pacemakers was associated with differences in mortality.
|
Methods |
|---|
|
TopAbstractIntroductionMethods Results Discussion References |
|---|
Sources of Data
We used the Medicare national hospital database (Medicare Provider Analysis and Review [MEDPAR]) file, which is composed of comprehensive hospital data on Medicare beneficiaries, to identify a random sample consisting of 20% of all Medicare patients who underwent permanent pacemaker implantation and were discharged alive or died in 1988, 1989, or 1990. The random 20% were selected on the basis of their having a 0 or 5 as the last digit of their Medicare health insurance claim number. We then created an analysis file from the MEDPAR file that was composed of patient-specific data on type of pacemaker and pacing lead used, principal and secondary diagnoses associated with the pacing hospitalization, patient demographic characteristics, and implant hospital characteristics. This analysis file was linked with the Medicare Health Insurance Skeletonized Eligibility Writeoff (HISKEW) file to obtain data on patient Medicare entitlement as well as vital status and date of death.
Patient Cohort
The study cohort was selected from 38 459
patients,
representing a randomly selected 20% of all Medicare
beneficiaries, who had an initial insertion of a permanent pacemaker as
identified by procedure codes 37.70 to 37.74 and 37.80 to 37.83
(International Classification of Diseases, Ninth
Revision–Clinical Modification) between January 1, 1988, and
December 31, 1990. Because our study focused on the elderly, we
excluded 1152 patients covered by Medicare due to end-stage renal
disease or disability and 910 patients younger than 65 years. We also
excluded 507 members of health maintenance organizations because the
Health Care Financing Administration does not receive data reliably on
these patients and 10 patients for whom data on diagnosis were
incomplete. Because our focus was on residents of the United States
receiving care in the United States, we excluded 282 patients who
resided outside the 50 states or the District of Columbia and 245
patients who received their implant in a non–US hospital. We also
excluded 238 patients with interrupted Part B Medicare coverage during
the study period, so the cohort was relatively homogeneous with respect
to insurance coverage. Because some patients were excluded on the basis
of meeting multiple criteria, a total of 2147 of the original 38 459
patients (5.6%) were excluded, leaving 36 312 Medicare patients in
our analysis cohort. Mortality data were available for the entire
cohort through 1 year after implantation and for the 23 120 patients
who received an implant in 1988 or 1989 through 2 years after
implantation.
Statistical Analysis
Univariate and Bivariate Analyses
We derived descriptive summaries of patient characteristics
(age, sex, race, residence, Medicaid status, principal and secondary
diagnoses), provider characteristics (teaching status, number of beds,
geographic location, ownership, and cardiac technological intensity as
measured by the presence of an active cardiac catheterization
laboratory), and outcome (mortality at 1 and 2 years after
implantation). Bivariate analysis testing for an association
between pacemaker system and year of implantation, patient and provider
characteristics, and mortality 1 year and 2 years after implantation
were undertaken using a Pearson 
2 statistic in
the case of discrete variables and a Student's t test in
the case of continuous variables.
Multivariate Analyses
To investigate the relation between patient and provider
characteristics and type of pacemaker system, we used a logistic
regression model in which the dependent variable was the log-odds of a
dual-chamber pacing system. The independent variables included the
patient and provider characteristics listed above and the year of
pacemaker implantation. Patient age was categorized by 5-year age
groups and entered as a series of dummy variables. The analyses were
adjusted for cardiac and noncardiac comorbidities as defined below.
Interactions between year of implantation and provider characteristics
were also examined.
A Cox proportional hazards model9 was used to characterize the association between mortality and selection of pacemaker system while adjusting for patient and provider characteristics. To identify any covariates that might not have been selected as bivariately significant predictors of mortality but might have become significant in a multiple regression model, we included all the predictors in the Cox model. Because we had complete 2-year follow-up mortality information for patients who received permanent pacemakers in 1988 and 1989 and only 1-year follow-up information for patients who received permanent pacemakers in 1990, we fitted two Cox models. In the first model, we included all patients in the 3-year cohort and modeled mortality through 1 year after implantation. In the second model, we included patients who received permanent pacemakers in 1988 and 1989 and modeled mortality through 2 years after implantation.
We controlled for patient comorbidity by including a number of binary variables that indicated the presence of the following cardiac conditions in the patient's discharge summary: atrioventricular block; congestive heart failure; chronic angina; acute myocardial infarction; prior myocardial infarction; stroke; stenosis or insufficiency of the mitral, aortic, tricuspid, or pulmonic valves; atrial fibrillation; noncardiac vascular disease; and hypertension. In addition, we included an ordinal variable that reflected the number of major noncardiac diagnoses to a maximum of four that the patient had listed on discharge. These conditions included pneumonia, urinary tract infection, sepsis, ruptured aneurysm, gastrointestinal bleed, ulcer, disorders of coagulation, renal dialysis, diabetes, pulmonary disease, neurological disease, dementia, paralysis, thyroid or pituitary dysfunction, adrenal dysfunction, parathyroid dysfunction, chronic and acute renal failure without dialysis, chronic liver disease, inflammatory bowel disease, cancer, abuse of alcohol and/or drugs, mental disorder, chronic arthritis, connective tissue disease, AIDS or symptomatic HIV infection, and HIV seropositive status.
|
Results |
|---|
|
TopAbstractIntroductionMethods Results Discussion References |
|---|
Univariate and Bivariate Analyses
A single-chamber ventricular pacemaker with or without rate modulation was implanted in 24 715 patients (68.1%). The remaining 11 597 patients (31.9%) received either a dual-chamber device (11 085 patients, or 30.5%) or an atrial single-chamber device (512 patients, or 1.4%). Because both the technical skill necessary to implant an atrial lead and the physiological benefit derived are expected to be similar for atrial and dual-chamber pacemakers, patients with either dual-chamber or atrial pacemakers were included in the "dual-chamber group."
The proportion of dual-chamber pacemakers implanted increased each year from 27.2% in 1988 (10 999 implants) to 30.8% in 1989 (12 121 implants) to 37.0% in 1990 (13 209 implants, P<.001).
Pacemaker Selection and Patient Characteristics
Dual-chamber
device–paced patients were younger and more
likely to be male than ventricular, single-chamber device–paced
patients (P<.001) (Table 1
). However, there
were no significant racial differences between groups
(P=.100). More ventricular, single-chamber device–paced
patients were Medicaid eligible than were dual-chamber device–paced
patients (P<.001).
|
More frequent selection of a dual-chamber system was made for patients with atrioventricular block. Characteristics associated with the use of more ventricular systems included atrial fibrillation, stroke, vascular disease, and a greater number of noncardiac diagnoses as listed in the discharge summary.
A decrease in the use of dual-chamber device pacing was observed for each additional noncardiac diagnosis. For example, a dual-chamber pacemaker was implanted in 33.0% of patients who had no noncardiac diagnoses listed; in 30.2% of patients with one diagnosis listed, in 28.6% of patients with two diagnoses listed, and in 26.2% of patients with three or more noncardiac diagnoses listed (P<.001).
Pacemaker Selection and Provider Characteristics
Patients who
received their implant in large, urban, teaching, and
private hospitals were more likely to receive a dual-chamber system
than were patients who received their implant in smaller, rural,
nonteaching, or public hospitals (all P<.001) (Table
2). In addition, the availability of a cardiac
catheterization laboratory in the implanting hospital also was
associated with the more frequent selection of a dual-chamber system
(P<.001).
|
Mortality
Patients who were paced by ventricular devices had
higher 1-year
and 2-year mortality rates than did patients who were paced by
dual-chamber devices (1-year mortality for the 1988, 1989, and 1990
cohort: 18.3% for ventricular devices versus 13.7% for dual-chamber
devices, P<.001, Fig 1; 2-year mortality for
the 1988 and 1989 cohort: 28.9% for ventricular devices versus 22.3%
for dual-chamber devices, P<.001, Fig 2).
|
|
Multivariate Analysis
A logistic regression model was used to
identify the independent
predictors of pacemaker mode selection (Table 3).
Patients with a pacemaker implanted in 1988 (odds ratio [OR], 0.60;
95% confidence interval [CI], 0.56 to 0.63) or in 1989 (OR, 0.73;
95% CI, 0.69 to 0.77) were less likely than were those with a
pacemaker implanted in 1990 to receive a dual-chamber pacemaker device.
Dual-chamber pacemaker implantation was found to be more likely in men
(OR, 1.18; 95% CI, 1.12 to 1.24 ) than in women. Older patients
received fewer dual-chamber pacemakers than did younger patients
(compared with ages 65 to 69-ages 70 to 74: OR, 0.89; 95% CI, 0.83 to
0.97; ages 75 to 79: OR, 0.74; 95% CI, 0.68 to 0.80; ages 80 to 84:
OR, 0.56; 95% CI, 0.51 to 0.60; and ages 85 and older: OR, 0.37; 95%
CI, 0.34 to 0.40). Black patients (OR, 0.90; 95% CI, 0.81 to 0.99)
were found to be marginally less likely to receive dual-chamber
pacemakers than were nonblack patients. Medicaid-eligible patients also
were less likely to receive a dual-chamber pacemaker (OR, 0.78; 95%
CI, 0.71 to 0.86) than were patients not eligible for Medicaid.
|
Patients with atrioventricular block also were more likely to receive a dual-chamber pacemaker than were patients with other implant diagnoses (OR, 1.59; 95% CI, 1.51 to 1.67). In addition, patients with congestive heart failure (OR, 1.14; 95% CI, 1.08 to 1.20), valve disease (OR, 1.17; 95% CI, 1.08 to 1.26), chronic angina (OR, 1.10; 95% CI, 1.04 to 1.16), or hypertension (OR, 1.14; 95% CI, 1.08 to 1.21) were more likely to receive a dual-chamber implant. Patients with atrial fibrillation (OR, 0.36; 95% CI, 0.34 to 0.39), acute myocardial infarction (OR, 0.86; 95% CI, 0.77 to 0.96), stroke (OR, 0.73; 95% CI, 0.67 to 0.81), vascular disease (0.72, 95% CI; 0.62 to 0.83), or other noncardiac diagnoses (OR, 0.86; 95% CI, 0.83 to 0.89) were less likely to receive a dual-chamber pacemaker than were patients without these diagnoses.
Patients implanted in the western US hospitals (OR, 1.19; 95% CI, 1.10 to 1.29) were more likely to receive a dual-chamber system than were those implanted in all other regions. Patients who received their pacemakers from a rural provider were less likely to receive a dual-chamber pacemaker (OR, 0.70; 95% CI, 0.65 to 0.76) than were those receiving their pacemakers from an urban provider. Finally, implantation in hospitals that were large (OR, 1.20; 95% CI, 1.13 to 1.28), were private (OR, 1.19; 95% CI, 1.10 to 1.28), or had a catheterization facility (OR, 1.47; 95% CI, 1.38 to 1.56) was associated with more likely selection of a dual-chamber system than a single-chamber system.
Mortality
Dual-chamber pacemaker implantation was a
significant independent
predictor of survival after control for the patient-level and
hospital-level characteristics identified above, including age (OR,
0.82 for death at 1 year; 95% CI, 0.77 to 0.87; Table 4). In
the cohort of 23 120 patients implanted in 1988
and 1989 for whom minimum 2-year follow-up was available (Table
5), dual-chamber pacing remained an independent
predictor of survival (OR, 0.82; 95% CI, 0.77 to 0.87). Other
significant covariates are listed in Tables 4 and
5.
|
|
|
Discussion |
|---|
|
TopAbstractIntroductionMethods Results Discussion References |
|---|
We found that the selection of dual-chamber or ventricular pacemakers is heterogeneous across different patient subgroups, as defined by demographic and clinical characteristics. These differences in the frequency of dual-chamber pacemaker implantation may represent underuse, overuse, or proper use of dual-chamber technology. In most cases, the variations in types of pacemakers that were observed across clinical subgroups are consistent with published guidelines.1 10 However, in some cases, the physiological underpinnings of these practice pattern variations are less clear.
For example, there are sound physiological reasons11 12 13 to expect a significant benefit from dual-chamber pacing in the elderly. However, advancing age was associated with decreased use of dual-chamber technology. This practice pattern may reflect existing professional guidelines in the United States1 that emphasize that dual-chamber pacing may be especially indicated in the "active or young patient." The less aggressive use of newer or more expensive therapies in the elderly has been reported for the use of thrombolytic therapy14 15 and for other post–myocardial infarction therapies.16 17 Yusuf and Furberg18 have postulated that physicians may treat older patients less aggressively due to concerns about the elderly being more prone to adverse effects of therapies, absence of data specifically addressing the elderly, and physicians' attitudes that lifesaving interventions are of limited use in the aged.19 All of these reasons may apply to the observed clinical practice in pacing.
Men received proportionally more dual-chamber pacemakers than women even after control for demographic and clinical characteristics. Similar sex differences in the management of patients with coronary disease have been reported.17 20 21 22 However, there are potential explanations that may have a unique application to a pacemaker population. Technical considerations may influence physicians' choices of pacing systems. Dual-chamber pacemakers tend to be larger than ventricular pacemakers. Thus, physicians may have preferred to implant a smaller (single-chamber) pacemaker in smaller patients (women) to avoid the possibility of pacemaker pocket erosion or simply to achieve a better cosmetic result. Unfortunately, this database did not have information on body weight and height, so this hypothesis could not be tested. Finally, the role of a sex bias on the part of implanting physicians (>90% are men23 ) leading to the withholding of a more expensive and more highly technological therapy from women cannot be examined with these data.
Black patients were marginally less likely than white patients to receive a dual-chamber pacemaker. This pattern may represent underuse of dual-chamber technology in blacks or overuse in whites. The racial difference noted for the present study was barely statistically significant and was smaller than the racial difference noted with the use of another highly technical cardiac service-revascularization after coronary angiography-reported by Ayanian et al.24 As Ayanian et al postulated, racial differences could be due to unmeasured socioeconomic or clinical issues, issues relating to patient preference, or racial bias.
It is noteworthy that race had much less of an effect on the selection of a dual-chamber pacemaker than did lower socioeconomic status (SES). Higher SES is known to be correlated with the use of more expensive medical therapies and technologies.14 25 The present study, in which Medicaid eligibility is used as a proxy for low SES and in which Medicaid-eligible patients received fewer dual-chamber pacemakers, extends these observations to the selection of implantable devices. The importance of SES may be related to at least two factors: unmeasured clinical differences and differential selection of hospitals. The hypothesis with respect to clinical differences is that poor patients have a different, unmeasured extent of disease that may be more appropriately treated with less complex devices. The hypothesis related to hospital selection is that poor patients are treated in hospitals that are less likely to use high-technology devices. Neither of these hypotheses was addressed in our study, and further study of their influence and interrelationship is warranted. Alternatively, more frequent use of less-expensive single-chamber devices may be encouraged by lower levels of or delays in physician and hospital reimbursement on behalf of indigent patients for the implantation and follow-up of pacemakers.
A greater proportion of patients with atrioventricular block received dual-chamber pacemakers than did patients with sinus node dysfunction. This is a logical consequence of the initial descriptions of benefit from atrial-tracking systems reported in patients with second- or third-degree atrioventricular block.2 However, more recent data suggest benefit from dual-chamber pacing for other diagnoses as well.
Patients with chronic atrial fibrillation are not candidates for dual-chamber pacing.1 Thus, although this database did not distinguish between paroxysmal and chronic atrial fibrillation, it is not surprising that the diagnosis of atrial fibrillation was an important predictor of ventricular pacing.
Multivariate analyses showed that there was more frequent use of dual-chamber pacing in patients with a history of congestive heart failure. Dual-chamber pacing is associated with a significant improvement in cardiac output,2 3 26 27 and the 1991 American College of Cardiology/American Heart Association Guidelines1 recommend dual-chamber pacing for patients with "significant hemodynamic need." Thus, more frequent use of dual-chamber pacing in this population is consistent with recommendations in the medical literature.
Patients with valvular heart disease were more likely to receive a dual-chamber pacemaker. The diagnosis of valvular heart disease includes patients with aortic valve disease. Clinicians might consider the presence of left ventricular hypertrophy in some of these patients an indication for dual-chamber pacing.
Hospital characteristics were independent predictors of choice of pacing system. Disparities of pacemaker selection among different types of hospitals may reflect less cost pressure on implanting physicians at private institutions to choose inexpensive pacemakers or differential reimbursement rates encouraging dual-chamber pacing in private, fee-for-service systems. In addition, differing degrees of technical sophistication of implanting physicians among hospitals may be important in determining pacemaker selection. Infrequent users of dual-chamber systems, for example, may avoid their implantation due to inexperience. However, the present database did not permit an analysis of the importance of implanting physician and hospital experience on pacemaker selection.
There were geographic correlates of pacemaker selection. Geographic variations in the practice of invasive cardiology have been described with regard to catheterization.28 However, the root causes of these interesting geographic differences cannot be fully addressed by this database or by any other database that does not analyze physician beliefs and their relation to clinical practice.
The present study shows that the proportion of dual-chamber pacemakers increased from 1988 to 1990. This is consistent with industry data and with the results of published surveys of pacing practice.23 29 However, in contrast to previously published studies, we demonstrate that this annual increase in dual-chamber pacing occurred independent of implant diagnosis or other covariates. Thus, clinicians' assessment of the need for dual-chamber pacing is changing on an annual basis. This change may be due to greater perceived benefit from dual-chamber pacing, yearly entry into the implanting physicians pool of more physicians trained to implant dual-chamber pacemakers, or differential reimbursement favoring dual-chamber implants. Additional studies will be necessary to define the relative contributions of these and any other reasons.
In summary, we describe important patient- and hospital-based variations in the clinical practice of cardiac pacing. Taken in isolation, these data cannot be interpreted to mean that there is underuse or overuse of dual-chamber technology in any particular patient or hospital subgroup. However, the potential for the clinical relevance of these findings is brought into sharper focus by the observation that dual-chamber pacing is associated with improved survival.
Improved outcomes with dual-chamber pacing have previously been reported by other investigators.4 5 6 30 31 32 33 34 These investigators have postulated that the hemodynamic benefit leading to the prevention of heart failure and stroke might account for a survival benefit. However, these smaller studies have been limited by the inability to control for important baseline clinical differences between patients treated with dual-chamber or atrial pacemakers and patients treated with ventricular pacemakers. Consequently, improvement in survival with dual-chamber pacing has remained controversial.35 The present study uncovered many baseline differences between ventricular and dual-chamber device–paced groups. However, after we controlled for imbalances in baseline characteristics, dual-chamber device–paced patients still demonstrated improved survival.
There are a number of potential weaknesses of the present study that limit the applicability of the survival results. Pacemaker selection was not randomized. Consequently, unknown, uncoded, confounding variables may exist that were evident to the clinician making the selection of pacing system but for which we cannot compensate with retrospective analyses of an administrative database. In addition, although the Medicare database contains specific codes relating to concomitant illnesses, the lack of specific clinical detail relating to a patient's functional status or physical condition limits the applicability of our results.
Therefore, these survival analyses should not be interpreted as leading to a final conclusion that dual-chamber pacing improves patient survival. Instead, the present study is hypothesis generating and underscores the need to design and execute prospective clinical trials of pacemaker mode selection to verify or refute these findings.
|
Acknowledgments |
|---|
This study was supported in part by PORT grant HS-06341 from the Agency for Health Care Policy and Research, Rockville, Md. The authors gratefully acknowledge the computational assistance provided by Karen Fung, MA; and Earl Davies, MS; and the competent secretarial assistance of Lori Martens.
Received June 27, 1994; revision received September 19, 1994; accepted September 28, 1994.
|
References |
|---|
|
TopAbstractIntroductionMethods Results Discussion References |
|---|
1. Guidelines for implantation of cardiac pacemakers and antiarrhythmia devices. A report of the American College of Cardiology/American Heart Association Task Force on Assessment of Diagnostic and Therapeutic Cardiovascular Procedures (Committee on Pacemaker Implantation). Dreifus LS, Fisch C, Griffin JC, Gillette PC, Mason JW, Parsonnet V. Special report. Circulation. 1991;84:455-467.
2.
Kruse I, Arnman K, Conradson T-B, Ryden L. A comparison of
the acute and long term hemodynamic effects of ventricular inhibited
and atrial synchronous ventricular inhibited pacing.
Circulation. 1982;65:846-855.
3. Stewart WJ, Dicola VC, Harthorne JW, Gillam LD, Weyman AE. Doppler ultrasound measurement of cardiac output in patients with physiological pacemakers. Am J Cardiol.. 1984;54:308-312.[Medline] [Order article via Infotrieve]
4. Rosenqvist M, Brandt J, Schuller H. Atrial versus ventricular pacing in sinus node disease: treatment comparison study. Am Heart J.. 1986;111:292-297. [Medline] [Order article via Infotrieve]
5. Rosenqvist M, Brandt J, Schuller H. Long term pacing in sinus node disease: effects of stimulation mode on cardiovascular morbidity and mortality. Am Heart J.. 1988;116:16-22. [Medline] [Order article via Infotrieve]
6. Hesselson AB, Parsonnet V, Bernstein AD, Bonavita GJ. Deleterious effects of long-term single-chamber ventricular pacing in patients with sick sinus syndrome: the hidden benefits of dual-chamber pacing. J Am Coll Cardiol.. 1992;19:1542-1549. [Abstract]
7. Eagle KA, Mulley AG, Singer DE, Schoenfeld D, Harthorne JW, Thibault GE. Single-chamber and dual-chamber cardiac pacemakers: a formal cost comparison. Ann Intern Med.. 1986;105:264-271.
8.
Ray SG, Griffith MJ, Jamieson S, Bexton RS, Gold RG. Impact
of the recommendations of the British Pacing and Electrophysiology
Group on pacemaker prescription and on the immediate costs of pacing in
the Northern Region. Br Heart J.. 1992;68:531-534.
9. Kuhn H, Sempos C. Statistical Methods in Epidemiology. New York, NY: Oxford University Press; 1989.
10.
Recommendations for pacemaker prescription for symptomatic
bradycardia: report of a working party of the British Pacing and
Electrophysiology Group. Br Heart J.. 1991;66:185-191.
11. Arora RR, Machac J, Goldman ME, Butler RN, Gorlin R, Horowitz SF. Atrial kinetics and left ventricular diastolic filling in the healthy elderly. J Am Coll Cardiol.. 1987;9:1255-1260. [Abstract]
12. Bonow RO, Vitale DF, Bacharach SL. Effects of aging on asynchronous left ventricular regional function and global ventricular filling in normal human subjects. J Am Coll Cardiol.. 1988;11:50-58. [Abstract]
13. Miller TR, Grossman SJ, Schectman KB. Left ventricular diastolic filling and its association with age. Am J Cardiol.. 1986;58:531-535. [Medline] [Order article via Infotrieve]
14. Rouleau JL, Moye LA, de Champlain J, Klein M, Bichet D, Packer M, et al. Activation of neurohumoral systems following acute myocardial infarction. Am J Cardiol.. 1991;68:80D-86D. [Medline] [Order article via Infotrieve]
15. Pashos CL, Normand ST, Garfinkle JB, Newhouse JP, Epstein AM, McNeil BJ. Trends in the use of drug therapies in patients with acute myocardial infarction: 1988-1992. J Am Coll Cardiol. In press.
16. Montague TJ, Ikuta RM, Wong RY, Bay KS, Teo KK, Davies NJ. Comparison of risk and patterns of practice in patients older and younger than 70 years with acute myocardial infarction in a two year period (1987-1989). Am J Cardiol.. 1991;68:843-847. [Medline] [Order article via Infotrieve]
17.
Pashos CL, Newhouse JP, McNeil BJ. Temporal changes in the
care and outcomes of elderly patients with acute myocardial infarction,
1987 through 1990. JAMA.. 1993;270:1832-1836.
18. Yusuf S, Furberg CD. Are we biased in our approach to treating elderly patients with heart disease? Am J Cardiol.. 1991;68:954-956. [Medline] [Order article via Infotrieve]
19.
Black JS, Sefcik T, Kapoor W. Health promotion and disease
prevention in the elderly: comparison of house staff and attending
physician attitudes and practices. Arch Int Med.. 1990;150:389-393.
20. Ayanian J, Epstein AM. Differences in the use of procedures between women and men hospitalized for coronary heart disease. N Engl J Med.. 1991;325:221-225. [Abstract]
21. Steingart RM, Packer M, Hamm P, Coglianese ME, Gersh B, Geltman EM, Sollano J, Katz S, Moye L, Basta LL. Sex differences in the management of coronary artery disease. N Engl J Med.. 1991;325:226-230. [Abstract]
22.
Udvarhelyi IS, Gatsonis C, Epstein AM, Pashos CL,
Newhouse JP, McNeil BJ. Acute myocardial infarction in the Medicare
population: process of care and clinical outcomes.
JAMA.. 1992;268:2530-2536.
23. Bernstein AD, Parsonnet V. Survey of cardiac pacing in the United States in 1989. Am J Cardiol.. 1992;69:331-338. [Medline] [Order article via Infotrieve]
24.
Ayanian JZ, Udvarhelyi IS, Gatsonis CA, Pashos CL, Epstein AM.
Racial differences in the use of revascularization procedures after
coronary angiography. JAMA.. 1993;269:2642-2646.
25.
Wenneker MB, Epstein AM. Racial inequalities in the use of
procedures for patients with ischemic heart disease in Massachusetts.
JAMA.. 1989;261:253-257.
26. Hoeschen RJ, Reimold SC, Lee RT, Plappert TJ, Lamas GA. The effect of posture on the response to atrioventricular synchronous pacing in patients with underlying cardiovascular disease. PACE Pacing Clin Electrophysiol.. 1991;14:756-759. [Medline] [Order article via Infotrieve]
27. Pearson AC, Janosik DL, Redd RM, Buckingham TA, Labovitz AJ. Hemodynamic benefit of atrioventricular synchrony: prediction from baseline Doppler-echocardiographic variables. J Am Coll Cardiol.. 1989;13:1613-1621. [Abstract]
28. Gatsonis C, Normand SL, Liu C, Morris C. Geographic variation of procedure utilization: a hierarchical modeling approach. Med Care.. 1993;31:Y554-Y559.
29. Parsonnet V, Bernstein A, Galasso D. Cardiac pacing practices in the United States in 1985. Am J Cardiol.. 1988;62:71-77. [Medline] [Order article via Infotrieve]
30. Reimold SC, Lamas GA, Cantillon CO, Antman EM. Dual-chamber pacing reduces the risk of recurrent atrial fibrillation. J Am Coll Cardiol.. 1993;21:202. Abstract.
31. Santini M, Alexidou G, Ansalone G, Cacciatore G, Cini R, Turitto G. Relation of prognosis in sick sinus syndrome to age, conduction defects and modes of permanent cardiac pacing. Am J Cardiol.. 1990;65:729-735. [Medline] [Order article via Infotrieve]
32. Sasaki Y, Furihata A, Suyama K, Furihata Y, Koike S, Kobayaski T, Shimotori M, Akahane K, Furuta S. Comparison between ventricular inhibited pacing and physiologic pacing in sick sinus syndrome. Am J Cardiol.. 1991;67:771-774. [Medline] [Order article via Infotrieve]
33. Alpert MA, Curtis JJ, Sanfelippo JF, Flaker GC, Walls JT, Mukerji V, Villareal D, Katti SK, Madigan NP, Krol RB. Comparative survival after permanent ventricular and dual chamber pacing for patients with chronic high degree atrioventricular block with and without preexistent congestive heart failure. J Am Coll Cardiol.. 1986;7:925-932. [Abstract]
34. Alpert MA, Curtis JJ, Sanfelippo JF, Flaker GC, Walls JT, Mukerji V, Villareal D, Katti SK, Madigan NP, Morgan RJ. Comparative survival following permanent ventricular and dual-chamber pacing for patients with chronic symptomatic sinus node dysfunction with and without congestive heart failure. Am Heart J.. 1987;113:958-965. [Medline] [Order article via Infotrieve]
35.
Sgarbossa EB, Pinski SL, Maloney JD. The role of pacing
modality in determining long-term survival in the sick sinus syndrome.
Ann Intern Med.. 1993;119:359-365.
This article has been cited by other articles:
 |
|
 |
|
  P. R Roberts Follow up and optimisation of cardiac pacing Heart, September 1, 2005; 91(9): 1229 - 1234. [Full Text] [PDF]
|
|
|
|
 |
|
 W. D. Toff, A. J. Camm, J. D. Skehan, and the United Kingdom Pacing and Cardiovascular Event Single-Chamber versus Dual-Chamber Pacing for High-Grade Atrioventricular Block N. Engl. J. Med., July 14, 2005; 353(2): 145 - 155. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. J. Greenspon, R. G. Hart, D. Dawson, A. S. Hellkamp, M. Silver, G. C. Flaker, E. Schron, L. Goldman, K. L. Lee, G. A. Lamas, et al. Predictors of stroke in patients paced for sick sinus syndrome J. Am. Coll. Cardiol., May 5, 2004; 43(9): 1617 - 1622. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 G. A. Lamas, K. A. Ellenbogen, and With the Assistance of Charles H. Hennekens, MD, D Evidence Base for Pacemaker Mode Selection: From Physiology to Randomized Trials Circulation, February 3, 2004; 109(4): 443 - 451. [Full Text] [PDF]
|
|
|
|
 |
|
 M. Brunner, M. Olschewski, A. Geibel, C. Bode, and M. Zehender Long-term survival after pacemaker implantation: Prognostic importance of gender and baseline patient characteristics Eur. Heart J., January 1, 2004; 25(1): 88 - 95. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
G. A. Lamas, K. L. Lee, M. O. Sweeney, R. Silverman, A. Leon, R. Yee, R. A. Marinchak, G. Flaker, E. Schron, E. J. Orav, et al. Ventricular Pacing or Dual-Chamber Pacing for Sinus-Node Dysfunction N. Engl. J. Med., June 13, 2002; 346(24): 1854 - 1862. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J. R. Pyatt, J. D. Somauroo, M. Jackson, A. D. Grayson, S. Osula, R. K. Aggarwal, R. G. Charles, and D. T. Connelly Long-term survival after permanent pacemaker implantation: analysis of predictors for increased mortality Europace, January 1, 2002; 4(2): 113 - 119. [Full Text] [PDF]
|
|
|
|
|
|
M. Vassolo and G.A. Lamas Dual-chamber vs ventricular pacing in the elderly: quality of life and clinical outcomes Eur. Heart J., November 2, 1999; 20(22): 1607 - 1608. [PDF]
|
|
|
|
|
|
A. Jahangir, W.-K. Shen, S. A. Neubauer, D. J. Ballard, S. C. Hammill, D. O. Hodge, C. M. Lohse, B. J. Gersh, and D. L. Hayes Relation between mode of pacing and long-term survival in the very elderly J. Am. Coll. Cardiol., April 1, 1999; 33(5): 1208 - 1216. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
L. Gianfranchi, M. Brignole, C. Menozzi, G. Lolli, and N. Bottoni Determinants of development of permanent atrial fibrillation and its treatment Europace, January 1, 1999; 1(1): 35 - 39. [Abstract] [PDF]
|
|
|
|
|
|
D. J. R. Hildick-Smith, J. T. Walsh, V. Parsonnet, M. Roelke, G. M. Gribbin, S. W. Parry, G. A. Lamas, L. Goldman, and C. Mangione Single-Chamber versus Dual-Chamber Pacemakers N. Engl. J. Med., August 27, 1998; 339(9): 630 - 632. [Full Text]
|
|
|
|
|
|
E. Ovsyshcher, D. L. Hayes, and S. Furman Dual-Chamber Pacing Is Superior to Ventricular Pacing : Fact or Controversy? Circulation, June 16, 1998; 97(23): 2368 - 2370. [Full Text] [PDF]
|
|
|
|
|
|
G. A. Lamas, E. J. Orav, B. S. Stambler, K. A. Ellenbogen, E. B. Sgarbossa, S. K. S. Huang, R. A. Marinchak, N.A. M. Estes, G. F. Mitchell, E. H. Lieberman, et al. Quality of Life and Clinical Outcomes in Elderly Patients Treated with Ventricular Pacing as Compared with Dual-Chamber Pacing N. Engl. J. Med., April 16, 1998; 338(16): 1097 - 1104. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
D J R Hildick-Smith, M D Lowe, S A Newell, P M Schofield, L M Shapiro, D L Stone, A A Grace, and M C Petch Ventricular pacemaker upgrade: experience, complications and recommendations Heart, April 1, 1998; 79(4): 383 - 387. [Abstract] [Full Text]
|
|
|
|
|
|
P. Alboni, C. Menozzi, M. Brignole, N. Paparella, G. Gaggioli, G. Lolli, and R. Cappato Effects of Permanent Pacemaker and Oral Theophylline in Sick Sinus Syndrome : The THEOPACE Study: A Randomized Controlled Trial Circulation, July 1, 1997; 96(1): 260 - 266. [Abstract] [Full Text]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||