Permanent cardiac pacemakers in the elderly

Common electrocardiogram measures are not associated with telomere length

AIMS

Aging is accompanied by telomere shortening. Increased telomere shortening is considered a marker of premature aging. Cardiac aging results in the development of cardiac pathologies. Electrocardiogram (ECG) measures reflect cardiac excitation, conduction, and repolarization. ECG measures also prolong with aging and are associated with cardiac pathologies including atrial fibrillation. As premature prolongation of ECG measures is observed, we hypothesized that such prolongation may be associated with telomere length.

METHODS AND RESULTS

We studied the large, community-based KORA F4 Study. Of 3,080 participants enrolled between 2006 and 2007 with detailed information on demographic, anthropometric, clinical, and ECG characteristics, 2,575 presented with available data on leukocyte telomere length. Telomere length was determined by real-time quantitative PCR and expressed relative to a single copy gene. We fitted multivariable adjusted linear regression models to associate the ECG measures RR-interval, PR-interval, QRS-duration, and heart rate corrected QTc with telomere length. In our cohort, the mean age was 54.9±12.9 years and 46.6% were men. Increased age was associated with shorter telomere length (p<0.01), and men had shorter telomere length than women (p<0.05). In unadjusted models, heart rate (p=0.023), PR-interval (p<0.01), and QTc-interval (p<0.01) were significantly associated with shorter telomere length. However, no significant associations remained after accounting for age, sex, and covariates.

CONCLUSIONS

ECG measures are age-dependent, but not associated with shortened telomere length as a marker of biological aging. Further research is warranted to clarify if shortened telomeres are associated with clinical cardiac pathologies including atrial fibrillation.

Pacing for drug-refractory or drug-intolerant hypertrophic cardiomyopathy

BACKGROUND

Hypertrophic cardiomyopathy (HCM) is a genetic disease with an autosomal-dominant inheritance for which negative inotropes are the most widely used initial therapies. Observational studies and small randomised trials have suggested symptomatic and functional benefits using pacing and several theories have been put forward to explain why. Pacing, although not the primary treatment for HCM, could be beneficial to patients with relative or absolute contraindications to surgery or alcohol ablation. Several randomised controlled trials comparing pacing to other therapeutic modalities have been conducted but no Cochrane-style systematic review has been done.

OBJECTIVES

To assess the effects of pacing in drug-refractory or drug-intolerant hypertrophic cardiomyopathy patients.

SEARCH METHODS

We searched the following on the 14/4/2010: CENTRAL (The Cochrane Library 2010, Issue 1), MEDLINE OVID (from 1950 onwards ), EMBASE OVID (from 1980 onwards ), Web of Science with Conference Proceedings (from 1970 onwards). No language restrictions were applied.

SELECTION CRITERIA

Randomised controlled trials of either parallel or crossover design that assess the beneficial and harmful effects of pacing for hypertrophic cardiomyopathy were included. When crossover studies were identified, we considered data only from the first phase.

DATA COLLECTION AND ANALYSIS

Data from included studies were extracted onto a pre-formed data extraction paper by two authors independently. Data was then entered into Review Manager 5.1 for analysis. Risk of bias was assessed using the guidance provided in the Cochrane Handbook. For dichotomous data, relative risk was calculated; and for continuous data, the mean differences were calculated. Where appropriate data were available, meta-analysis was performed. Where meta-analysis was not possible, a narrative synthesis was written. A QUROUM flow chart was provided to show the flow of papers.

MAIN RESULTS

Five studies (reported in 10 papers) were identified. However, three of the five studies provided un-usable data. Thus the data from only two studies (reported in seven papers) with 105 participants were included for this review. There was insufficient data to compare results on all-cause mortality, cost effectiveness, exercise capacity, Quality of life and Peak O2 consumption.When comparing active pacing versus placebo pacing on exercise capacity, one study showed that exercise time decreased from (13.1 ± 4.4) minutes to (12.6 ± 4.3) minutes in the placebo group and increased from (12.1 ± 5.6) minutes to (12.9 ± 4.2) minutes in the treatment group (MD 0.30; 95% CI -1.54 to 2.14). Statistically significant data from the same study showed that left ventricular outflow tract obstruction decreased from (71 ± 32) mm Hg to (52 ± 34) mm Hg in the placebo group and from (70 ± 24) mm Hg to (33 ± 27) mm Hg in the active pacing group (MD -19.00; 95% CI -32.29 to -5.71). This study was also able to show that New York Heart Association (NYHA) functional class decreased from (2.5 ± 0.5) to (2.2 ± 0.6) in the inactive pacing group and decreased from (2.6 ± 0.5) to (1.7 ± 0.7) in the placebo group (MD -0.50; 95% CI -0.78 to -0.22).When comparing active pacing versus trancoronary ablation of septal hypertrophy (TASH), data from one study showed that NYHA functional class decreased from (3.2 ± 0.7) to (1.5 ± 0.5) in the TASH group and decreased from (3.0 ± 0.1) to (1.9 ± 0.6) in the pacemaker group. This study also showed that LV wall thickness remained unchanged in the active pacing group compared to reduction from (22 ± 4) mm to (17 ± 3) mm in the TASH group (MD 0.60; 95% CI -5.65 to 6.85) and that LV outflow tract obstruction decreased from (80 ± 35.5) mm Hg in the TASH group to (49.3 ± 37.7) mm Hg in the pacemaker group.

AUTHORS' CONCLUSIONS

Trials published to date lack information on clinically relevant end-points. Existing data is derived from small trials at high risk of bias, which concentrate on physiological measures. Their results are inconclusive. Further large and high quality trials with more appropriate outcomes are warranted.

Alzheimer's disease: is pacemaker implantation safe?

AIM

To evaluate the safety of pacemaker implantation in patients with Alzheimer's disease (AD).

METHODS

We reviewed all cases admitted to our institution between January 2008 and June 2009, with symptomatic bradyarrhythmia for whom a permanent pacemaker was implanted. Beginning in June 2009, we prospectively collected data from all patients with the same diagnosis and procedure. Patients with a diagnosis of AD were included in the study. The risks and frequency of complications due to the pacemaker implantation were evaluated. Because of the older age of patients, they were divided into 2 groups to define the effect of age on complication rate. Group 1 consisted of patients aged <75 years, and group 2 consisted of those who are ≥75 years.

RESULTS

Among the 574 patients with permanent pacemaker, 20 patients (3.4%) had a diagnosis of AD. Three patients with an AD experienced a complication and all were in group 2. However, the rate of complication was not significant within groups (P = 1.000). Reoperation was needed for all of them, and it was significantly higher in patients with AD than in patients without a concomitant disease (P = .006). Patients in group 2 had 3 times higher rate of complication (21.4%) than those without an AD and aged ≥75 years (7.1%; P = .125).

CONCLUSION

Pacemaker implantation may be of risk in patients with AD, especially in those aged ≥75 years.

Dual chamber versus single chamber ventricular pacemakers for sick sinus syndrome and atrioventricular block

BACKGROUND

Dual chamber pacing or single chamber atrial pacing ('physiologic' pacing) is believed to have an advantage over single chamber ventricular pacing in that it resembles cardiac physiology more closely by maintaining atrioventricular (AV) synchrony and dominance of the sinus node, which in turn may reduce cardiovascular morbidity and mortality thus contributing to patient survival and quality of life. However, a significant proportion of pacemakers currently implanted are single chamber ventricular pacemakers.

OBJECTIVES

The objective of this review was to assess the short- and long-term clinical effectiveness of dual chamber pacemakers compared to single chamber ventricular pacemakers in adults with AV block, sick sinus syndrome or both. An additional objective was to assess separately any potential differences in effectiveness between dual chamber pacing and single chamber atrial pacing. The clinical effectiveness of single chamber atrial pacing versus single chamber ventricular pacing was not examined.

SEARCH STRATEGY

The Cochrane Controlled Trials Register (The Cochrane Library Issue 3, 2002), MEDLINE (1966 to 2002), EMBASE (1980 to 2002) and the Science Citation Index (1980 to 2002) were searched on 19th August 2002. Citation lists and web sites were checked and researchers in the field contacted.

SELECTION CRITERIA

Parallel group or crossover randomised controlled trials of at least 48 hours duration comparing dual chamber pacing and single chamber ventricular pacing, and investigating cardiovascular morbidity, mortality, patient related quality of life, exercise capacity and complication rates.

DATA COLLECTION AND ANALYSIS

Data was extracted onto pre-piloted data extraction forms. Quality assessment was undertaken using a checklist, with a sub-sample of quality data independently extracted by a second reviewer. Where appropriate data was available, meta-analysis was performed. Where meta-analysis was not possible, the number of studies showing a positive, neutral or negative direction of effect and statistical significance were simply counted.

MAIN RESULTS

Five parallel and 26 crossover randomised controlled trials were identified. The quality of reporting was found to be poor. Pooled data from parallel studies shows a statistically non-significant preference for physiologic pacing (primarily dual chamber pacing) for the prevention of stroke, heart failure and mortality, and a statistically significant beneficial effect regarding the prevention of atrial fibrillation (odds ratio (OR) 0.79, 95% CI 0.68 to 0.93). Both parallel and crossover studies favour dual chamber pacing with regard to pacemaker syndrome (parallel: Peto OR 0.11, 95% CI 0.08 to 0.14; crossover: standardised mean difference (SMD) -0.74, 95% CI - 0.95 to -0.52). Pooled data from crossover studies shows a statistically significant trend towards dual chamber pacing being more favourable in terms of exercise capacity (SMD -0.24, 95% CI -0.03 to -0.45). No individual studies reported a significantly more favourable outcome with single chamber ventricular pacing.

REVIEWERS' CONCLUSIONS

This review shows a trend towards greater effectiveness with dual chamber pacing compared to single chamber ventricular pacing, which supports the current British Pacing and Electrophysiology Group's Guidelines regarding atrioventricular block. Additional randomised controlled trial evidence from ongoing trials in this area will further inform the debate.

Final-year-of life pacemaker recipients

BACKGROUND

Older persons who have initial cardiac pacemakers implanted during their final year of life have not been characterized as a group, which makes it difficult to evaluate the suitability of some of their health services utilizations.

OBJECTIVE

To help determine how prudently pacemakers are used in this group, we assessed its pacemaker candidates from the perspective of health and ability to perform physical activities of daily living.

DESIGN

A retrospective, population-based, cross-sectional study.

SETTING

The 1993 National Mortality Followback Survey.

PARTICIPANTS

An estimated 1,647,955 persons aged 65 years or older who died in the US in 1993.

MEASUREMENTS

Demographic and cause-of-death frequencies obtained by analyzing age, sex, race, and underlying cause-of-death variables in the survey. For persons who had initial pacemakers implanted during their last year of life, we determined the percent of persons, within 10-year age groups, who had no difficulty at any time during their final year of life performing 11 specific physical activities of daily living (e.g., climbing stairs, preparing meals, bathing). These data were obtained from negative responses to questions that asked if the decedents, at any time during their last year of life, had difficulty performing the specific activities.

RESULTS

Of the estimated 78,941 persons aged 65 years or older with a pacemaker who died in the US in 1993, 14,158 (18%) had their first pacemaker implanted during their last year of life. Estimated median survival of the final-year-of-life recipients of pacemakers after pacemaker implantation was 5 months. Compared with the general older population that died in 1993, the final-year-of-life recipients of pacemakers group had higher percentages of persons who died of acute disorders (49% vs 19%) and who lived alone in a private home (47% vs 20%), and a lower percentage of persons with Alzheimer's disease (1% vs 7%). The age-stratified means of the percentages of final-year-of-life recipients of pacemakers who had no difficulty performing each physical activity of daily living were all greater than 50.

CONCLUSION

Our results suggest that older persons who had initial pacemakers implanted during their final year of life and who died in 1993 were not terminally ill, inactive pacemaker candidates, in general, but relatively independent, physically functional candidates who frequently died abruptly. The physical, mental, and life expectancy factors recommended for consideration by expert guidelines for the implantation of cardiac pacemakers were generally applied to persons in this subgroup.

The epidemiology of cardiac pacemakers in the older US population

OBJECTIVES

This study estimates the age distribution of older patients (>64 years) receiving implantable cardiac pacemakers in non-federal US hospitals and determines major characteristics of this group using a massive, nationally representative sample of inpatient discharge records.

DESIGN

Discharge records were obtained from the 1992 Nationwide Inpatient Sample. Correlation with census data from 1992 was used to determine age and gender specific rates.

SETTING

The Nationwide Inpatient Sample is a 20% stratified probability sample of non-federal US hospitals.

PATIENTS

Records of all recipients (26,425) of an initial or replacement pacemaker were selected.

RESULTS

Individuals 65 years of age and older received an estimated 131,361 initial and replacement pacemaker pulse generators (87% of the total) in non-federal US hospitals in 1992. Pacemaker implantation was performed in urban teaching hospitals (28.9%), non-teaching urban hospitals (57.8%), and rural hospitals (13.3%). The age specific implantation rates per 100,000 population were 226.5 (age 65-74 years), 585.9 (age 75-84 years), 874.9 (age 85-94 years), and 540.4 (more than 94 years). The age-adjusted rate for men was 70% greater than the corresponding rate for women. Major diagnoses of implant recipients included atrioventricular block (37.8%) and atrial fibrillation (28.5%). Two percent of pacemaker recipients died before discharge.

CONCLUSIONS

The rate of pacemaker implantation increases sharply up to age 95. As the number of older people in the US population grows, particularly those in the age ranges greater than 75 and 85 years, a sharply increased number of pacemakers will be implanted unless other factors decrease the need for these devices. The data also demonstrate diffusion of this technology from academic centers.

Syncope in the elderly

Age-related physiologic changes and disease-related abnormalities predispose older adults to syncope. It is important to know the physiologic changes that occur with normal aging to understand better their interaction with disease processes and to facilitate better evaluation and treatment of syncope when it occurs. Attention to situational stresses, such as posture changes, meals, or medications, is also likely to increase the diagnostic yield and improve therapeutic strategies that can reduce morbidity and potential mortality of recurrent episodes. Therapy should be directed toward minimizing multiple factors that contribute to syncope, avoiding iatrogenic medication effects, and treating specific contributory diseases.