Sinus Node Dysfunction.

Sinus node dysfunction (SND) is a multifaceted disorder most prevalent in older individuals, but may also occur at an earlier age. In most cases, the SND diagnosis is ultimately established by documenting its ECG manifestations. EPS has limited utility. The treatment strategy is largely dictated by symptoms and ECG manifestations. Not infrequently, both bradycardia and tachycardia coexist in the same patients, along with other diseases common in the elderly (e.g., hypertension, coronary artery disease), thereby complicating treatment strategy. Prevention of the adverse consequences of both bradyarrhythmia and tachyarrhythmia is important to reduce susceptibility to syncope, falls, and thromboembolic complications.

Sinus Node Dysfunction.

Sinus node dysfunction (SND) is a multifaceted disorder most prevalent in older individuals, but may also occur at an earlier age. In most cases, the SND diagnosis is ultimately established by documenting its ECG manifestations. EPS has limited utility. The treatment strategy is largely dictated by symptoms and ECG manifestations. Not infrequently, both bradycardia and tachycardia coexist in the same patients, along with other diseases common in the elderly (e.g., hypertension, coronary artery disease), thereby complicating treatment strategy. Prevention of the adverse consequences of both bradyarrhythmia and tachyarrhythmia is important to reduce susceptibility to syncope, falls, and thromboembolic complications.

Do assessments of cardiorespiratory and muscular fitness influence subsequent reported physical activity? A randomized controlled trial.

BACKGROUND: Regular physical activity and exercise provide many health benefits. These health benefits are mediated in large part through cardiorespiratory fitness and muscular strength. As most individuals have not had an assessment of their personal cardiorespiratory fitness or muscular strength we investigated if measurements of cardiorespiratory fitness and muscular strength would influence an individual's subsequent self-reported exercise and physical activity. METHODS: Volunteer subjects at a State Fair were randomized in 1:1 parallel fashion to control and intervention groups. The baseline Exercise Vital Sign (EVS) and type of physical activity were obtained from all subjects. The intervention group received estimated maximum oxygen uptake (VO2max) using a step test and muscular strength using a hand grip dynamometer along with age-specific norms for both measurements. All subjects were provided exercise recommendations. Follow up surveys were conducted at 3, 6 and 12 months regarding their EVS and physical activity. RESULTS: One thousand three hundred fifteen individuals (656 intervention, 659 control) were randomized with 1 year follow up data obtained from 823 subjects (62.5%). Baseline mean EVS was 213 min/week. No change in EVS was found in either group at follow-up (p = 0.99). Subjects who were less active at baseline (EVS < 150) did show an increase in EVS (86 to 146) at 6 months (p < 0.05). At 3 months the intervention group increased resistance training (29.1 to 42.8%) compared to controls (26.3 to 31.4%) (p < 0.05). Lifestyle physical activity increased in the intervention group at 3 months (27.7 to 29.1%) and 6 months (25%) whereas it declined in the control group at 3 months (24.4 to 20.1%) and 6 months (18.7%) (p < 0.05). CONCLUSION: Providing VO2max estimates and grip strength did not produce an increase in overall physical activity. The EVS and exercise recommendations did however produce an increase in physical activity in less active individuals. In a very active population the VO2max estimate and measured grip strength did increase lifestyle activity and resistance training. Wider adoption of these measures could be effective in promoting physical activity and resistance training. TRIAL REGISTRATION: clinicaltrials.gov NCT03518931 Registered 05/08/2018 -retrospectively registered.

Impact of Denervation by Heart Transplantation on Post-operative Atrial Fibrillation Susceptibility.

Atrial fibrillation is common following cardiac and non-cardiac thoracic surgery and is associated with poorer outcomes, including: increased risk of stroke, hemodynamic instability, prolonged hospital stay, and increased mortality. Current understanding suggests that post-op atrial fibrillation results from the interplay of local and systemic operative inflammation, increased sympathetic activity, perhaps the release of free radical species in the perioperative period, and the patient's underlying cardiac substrate. Cardiac denervation following orthotopic heart transplant (OHT) using modern bicaval techniques presents a unique opportunity to study the relative contribution of the autonomic nervous system to post-op atrial fibrillation susceptibility. Observational studies show a reduced incidence of post-operative atrial fibrillation following orthotopic heart transplant compared to other cardiac and thoracic surgeries. Moreover, comparison of atrial fibrillation rates with double lung transplant recipients suggests that cardiac denervation has a contribution apart from surgical pulmonary vein isolation alone. This report reviews current concepts of the mechanisms of post-op atrial fibrillation with a focus on the role of the autonomic nervous system, the autonomic regulation of the native heart, and evidence regarding the impact of cardiac denervation following OHT.

Implantable Cardioverter-Defibrillator Use in Patients With Left Ventricular Assist Devices: A Systematic Review and Meta-Analysis.

OBJECTIVES: This study evaluated the impact of implantable cardioverter-defibrillators (ICDs) on mortality in patients with left ventricular assist devices (LVADs) by conducting a systematic review and meta-analysis of published studies. BACKGROUND: The burden of ventricular arrhythmias in patients with LVADs is high. Prior studies assessing the impact of ICD on survival of patients with LVADs have yielded conflicting results. METHODS: Relevant studies from January 2000 through October 2015 were identified in the databases PubMed and OVID. Weighted relative risks were estimated using random effects meta-analysis techniques. RESULTS: Six observational studies (n = 937) were included. Patients were 53 ± 12 years of age, and 80% were male. Bridge-to-transplantation was the indication for LVAD use in 93% of the patients. A continuous-flow (CF) LVAD was present in 39% of patients. Mean left ventricular ejection fraction was 16 ± 6%. An ICD was present in 355 patients (38%). During a mean follow-up of 7 months, 241 patients (26%) died (16% in the ICD group vs. 32% in the no-ICD group). Presence of an ICD was associated with a 39% relative risk reduction in all-cause mortality (RR: 0.61; 95% confidence interval [CI]: 0.46 to 0.82; p < 0.01). Among subgroup of patients with CF-LVAD (n = 361), ICD use was associated with a statistically nonsignificant trend toward improved survival (RR: 0.76; 95% CI: 0.51 to 1.12; p = 0.17). CONCLUSIONS: ICD use was associated with a significant reduction in mortality in LVAD patients, however, this effect was not significant in patients with CF-LVADs. Although these data support the use of ICDs, larger randomized trial data are strongly warranted to evaluate ICD effectiveness in patients with current generation LVADs.