Long-Term Mortality Outcomes According to the Frequency of Right Ventricular Pacing in Veterans

Background. Right ventricular pacing (RVP) has been associated with adverse outcomes, including heart failure and death. Minimizing RVP has been proposed as a therapeutic goal for a variety of pacing devices and indications. Objective. Quantify survival according to frequency of RVP in veterans with pacemakers. Methods. We analyzed electrograms from transtelephonic monitoring of veterans implanted with pacemakers between 1995 and 2005 followed by the Eastern Pacemaker Surveillance Center. We compared all cause mortality and time to death between patients with less than 20% and more than 80% RVP. Results. Analysis was limited to the 7198 patients with at least six trans-telephonic monitoring records (mean = 21). Average follow-up was 5.3 years. Average age at pacemaker implant was significantly lower among veterans with <20% RVP (67 years versus 72 years; P < .0001). An equal proportion of deaths during follow-up were noted for each group: 126/565 patients (22%) with <20% RVP and 1113/4968 patients (22%) with >80% RVP. However, average post-implant survival was 4.3 years with <20% RVP versus 4.7 years with >80% RVP (P < .0001). Conclusions. Greater frequency (>80%) of RVP was not associated with higher mortality in this population of veterans. Those veterans utilizing <20% RVP had a shortened adjusted survival rate (P = .0016)

A genome-wide association study of aging

AbstractHuman longevity and healthy aging show moderate heritability (20%–50%). We conducted a meta-analysis of genome-wide association studies from 9 studies from the Cohorts for Heart and Aging Research in Genomic Epidemiology Consortium for 2 outcomes: (1) all-cause mortality, and (2) survival free of major disease or death. No single nucleotide polymorphism (SNP) was a genome-wide significant predictor of either outcome (p < 5 × 10−8). We found 14 independent SNPs that predicted risk of death, and 8 SNPs that predicted event-free survival (p < 10−5). These SNPs are in or near genes that are highly expressed in the brain (HECW2, HIP1, BIN2, GRIA1), genes involved in neural development and function (KCNQ4, LMO4, GRIA1, NETO1) and autophagy (ATG4C), and genes that are associated with risk of various diseases including cancer and Alzheimer's disease. In addition to considerable overlap between the traits, pathway and network analysis corroborated these findings. These findings indicate that variation in genes involved in neurological processes may be an important factor in regulating aging free of major disease and achieving longevity

Genome-wide meta-analysis of muscle weakness identifies 15 susceptibility loci in older men and women.

Low muscle strength is an important heritable indicator of poor health linked to morbidity and mortality in older people. In a genome-wide association study meta-analysis of 256,523 Europeans aged 60 years and over from 22 cohorts we identify 15 loci associated with muscle weakness (European Working Group on Sarcopenia in Older People definition: n = 48,596 cases, 18.9% of total), including 12 loci not implicated in previous analyses of continuous measures of grip strength. Loci include genes reportedly involved in autoimmune disease (HLA-DQA1 p = 4 × 10-17), arthritis (GDF5 p = 4 × 10-13), cell cycle control and cancer protection, regulation of transcription, and others involved in the development and maintenance of the musculoskeletal system. Using Mendelian randomization we report possible overlapping causal pathways, including diabetes susceptibility, haematological parameters, and the immune system. We conclude that muscle weakness in older adults has distinct mechanisms from continuous strength, including several pathways considered to be hallmarks of ageing

A genome-wide association study of aging

Human longevity and healthy aging show moderate heritability (20–50%). We conducted a meta-analysis of genome-wide association studies from nine studies from the Cohorts for Heart and Aging Research in Genomic Epidemiology Consortium for two outcomes: a) all-cause mortality and b) survival free of major disease or death. No single nucleotide polymorphism (SNP) was a genome-wide significant predictor of either outcome (p < 5 × 10−8). We found fourteen independent SNPs that predicted risk of death, and eight SNPs that predicted event-free survival (p < 10−5). These SNPs are in or near genes that are highly expressed in the brain (HECW2, HIP1, BIN2, GRIA1), genes involved in neural development and function (KCNQ4, LMO4, GRIA1, NETO1) and autophagy (ATG4C), and genes that are associated with risk of various diseases including cancer and Alzheimer’s disease. In addition to considerable overlap between the traits, pathway and network analysis corroborated these findings. These findings indicate that variation in genes involved in neurological processes may be an important factor in regulating aging free of major disease and achieving longevity

Genome-wide association study in 79,366 European-ancestry individuals informs the genetic architecture of 25-hydroxyvitamin D levels

Vitamin D is a steroid hormone precursor that is associated with a range of human traits and diseases. Previous GWAS of serum 25-hydroxyvitamin D concentrations have identified four genome-wide significant loci (GC, NADSYN1/DHCR7, CYP2R1, CYP24A1). In this study, we expand the previous SUNLIGHT Consortium GWAS discovery sample size from 16,125 to 79,366 (all European descent). This larger GWAS yields two additional loci harboring genome-wide significant variants (P = 4.7x10(-9) at rs8018720 in SEC23A, and P = 1.9x10(-14) at rs10745742 in AMDHD1). The overall estimate of heritability of 25-hydroxyvitamin D serum concentrations attributable to GWAS common SNPs is 7.5%, with statistically significant loci explaining 38% of this total. Further investigation identifies signal enrichment in immune and hematopoietic tissues, and clustering with autoimmune diseases in cell-type-specific analysis. Larger studies are required to identify additional common SNPs, and to explore the role of rare or structural variants and gene-gene interactions in the heritability of circulating 25-hydroxyvitamin D levels.Peer reviewe

Genome-wide meta-analysis of muscle weakness identifies 15 susceptibility loci in older men and women

Low muscle strength is an important heritable indicator of poor health linked to morbidity and mortality in older people. In a genome-wide association study meta-analysis of 256,523 Europeans aged 60 years and over from 22 cohorts we identify 15 loci associated with muscle weakness (European Working Group on Sarcopenia in Older People definition: n = 48,596 cases, 18.9% of total), including 12 loci not implicated in previous analyses of continuous measures of grip strength. Loci include genes reportedly involved in autoimmune disease (HLA-DQA1p = 4 × 10−17), arthritis (GDF5p = 4 × 10−13), cell cycle control and cancer protection, regulation of transcription, and others involved in the development and maintenance of the musculoskeletal system. Using Mendelian randomization we report possible overlapping causal pathways, including diabetes susceptibility, haematological parameters, and the immune system. We conclude that muscle weakness in older adults has distinct mechanisms from continuous strength, including several pathways considered to be hallmarks of ageing

A Genome-Wide Association Meta-Analysis of Circulating Sex Hormone-Binding Globulin Reveals Multiple Loci Implicated in Sex Steroid Hormone Regulation

WOS:000306840400020Peer reviewe

How Should Implantable Cardioverter-Defibrillator Lead Failures be Managed and What is the Role of Lead Extraction?

Despite remarkable advances in design, implantable cardioverter-defibrillator (ICD) leads remain the component most susceptible to failure, which often leads to substantial adverse clinical outcomes. This article focuses on management strategies when ICD lead systems fail. Two cases involving management decisions for ICD lead failures are presented and discussed. One involves a common mode of presentation, inappropriate shocks. The second involves an alert in a patient with a complex system and multiple comorbidities. Although a systematic approach is outlined, management decisions must be balanced by a risk-and-benefit assessment of the individual patient. © 2012 Elsevier Inc

How should Implantable cardioverter-defibrillator lead failures be managed and what is the role of lead extraction?

Despite remarkable advances in design, implantable cardioverter-defibrillator (ICD) leads remain the component most susceptible to failure, which often leads to substantial adverse clinical outcomes. This article focuses on management strategies when ICD lead systems fail. Two cases involving management decisions for ICD lead failures are presented and discussed. One involves a common mode of presentation, inappropriate shocks. The second involves an alert in a patient with a complex system and multiple comorbidities. Although a systematic approach is outlined, management decisions must be balanced by a risk-and-benefit assessment of the individual patient. © 2012 Elsevier Inc

Relation between repolarization and refractoriness during programmed electrical stimulation in the human right ventricle: Implications for ventricular tachycardia induction

Background: Although programmed electrical stimulation is widely used for provoking sustained ventricular tachycardia (VT), the mechanism by which repetitive extrastimulation evokes VT is still little understood. Specifically, it is not clear why several closely coupled extrastimuli are frequently required to induce VT. Although regularly paced human ventricular myocardium exhibits a near constant relation between myocardial repolarization and refractoriness, the effect of repetitive extrastimulation on the relation between repolarization and excitability in the human heart and its relevance for arrhythmia induction by programmed stimulation are unknown. We hypothesized that the induction of VT by repetitive extrastimulation is facilitated by an altered relation between repolarization and refractoriness, and this leads to disturbances in ventricular impulse propagation, which trigger the onset of VT. Methods and Results: Twenty-one patients undergoing routine electrophysiological study were paced from the right ventricular apex and outflow tract endocardium with monophasic action potential-pacing catheters placed at both sites simultaneously. Monophasic action potential durations (APDs) and effective refractory periods (ERPs) were measured simultaneously at each site, during regular stimulation (S1- S1) at 400-ms cycle length and during three consecutive extrastimuli (S2 through S4) at the closest coupling intervals at which all three extrastimuli still resulted in capture. Measurements further included the repolarization level at which the earliest capture occurred, the ratio between ERP and APD, and the propagation time between the pacing and distant recording site. APD and ERP both shortened progressively with each extrastimulus. APD at 90% repolarization decreased from a baseline (SI) of 238.1±19.7 ms by 14.9% at S2, 18.9% at S3, and 22.9% at S4 (P\u3c.0001, S1 versus S4). ERP decreased from 233.1 ± 19.7 ms (S1) to 180.0±41.9 ms (53) (P\u3c.0001, S1 versus S3). While ERP shortening occurred mainly on the basis of APD shortening, there was an additional factor that contributed to ERP shortening independent of APD shortening. Each consecutive extrastimulus was able to elicit a propagated response at earlier repolarization levels than the previous one: the earliest capture for S2 occurred at 85.5±10.2% of complete repolarization, for S3 at 83.9±10.5%, and for S4 at 78.4±11.2% (P\u3c.05 for S2 versus S3; P\u3c.05 for S3 versus S4; P\u3c.01 for S2 versus S4). This progressive \u27encroachment\u27 of the earliest capture stimulus onto the preceding repolarization phase (at progressively less repolarized levels) correlated with a progressive delay of impulse propagation between the pacing site and the second recording site: propagation time increased from baseline (S1) by 10.5±1.3% with S2 to 19.0±1.6% with S3 and to 22.5±2.8% with S4 (P\u3c.05, S4 versus S1). VT was induced in 11 of 21 patients. Nine of these had VT induced only when significant encroachment of extrastimuli on the preceding repolarization phase (\u3c81.3±7.0%) and associated conduction slowing (\u3e16.6±1.8%) were present. Conclusions: Repetitive extrastimulation not only shortens APD and subsequently ERP but also alters the ERP/APD relation by allowing capture to occur at progressively less complete repolarization levels. This progressive encroachment onto the preceding repolarization phase is associated with impaired impulse propagation and a high incidence of VT induction. This may help explain how repetitive, closely coupled extrastimulation induces ventricular tachycardia in the human heart