Background Sleep disturbance caused by obstructive sleep apnea is recognized as a contributing factor to adverse cardiovascular outcomes. However, the effect of restless legs syndrome (RLS), another common cause of fragmented sleep, on cardiac structure, function and long-term outcomes is not known. We assessed the effect of frequent leg movement during sleep on cardiac structure and outcomes in patients with RLS. Methods In our retrospective study, RLS patients referred for polysomnography were divided into those with frequent (periodic movement index >35/hour) and infrequent (≤35/hour) leg movement during sleep. Long-term outcomes were determined using Kaplan-Meier and logistic regression models. Results Of 584 patients, 47% had periodic movement index >35/hour. Despite similarly preserved left ventricular ejection fraction, the group with periodic movement index >35/hour had significantly higher left ventricular mass and mass index reflective of left ventricular hypertrophy (LVH). There were no significant baseline differences in the proportion of patients with hypertension, diabetes, hyperlipidemia, prior myocardial infarction, stroke or heart failure or use of antihypertensive medications between the groups. Patients with frequent periodic movement index were older, predominantly male and had more prevalent coronary artery disease and atrial fibrillation. However, on multivariate analysis, periodic movement index >35/hour remained the strongest predictor for LVH (odds ratio 2.45, 95% confidence interval 1.67–3.59, P<0.001). Advanced age, female sex and apnea-hypopnea index were other predictors for LVH. Patients with periodic movement index >35/hour had significantly higher heart failure and mortality rates over 33-month median follow-up. Conclusions Frequent periodic leg movement during sleep is an independent predictor of severe LVH and associated with increased cardiovascular morbidity and mortality.

BACKGROUND The use of coronary sinus (CS) sheaths to deliver stylet-driven leads (SDLs) for His-bundle pacing (HBP) has not been described. Conventionally, HBP is achieved using a styletless lead delivered through a customized catheter. OBJECTIVE The purpose of this study was to characterize the acute and early-term HBP experience with stylet-driven, active-fixation leads delivered through CS sheaths compared to the conventional approach. METHODS Delivery of Medtronic 4471 and 7742 SDLs was attempted in 27 patients. Delivery was facilitated using CS guide catheters and custom-shaped stylets. Procedural characteristics and lead performance were compared to those of a group of 17 patients in whom delivery of 3830 lumen-less leads (LLLs) was attempted. Patients had heterogeneous pacing indications. RESULTS HBP with SDL was successful in 24 of 27 patients(89%) compared to 15 of 17 patients (88%) in the LLL group. Mean procedural and fluoroscopy times in the SDL and LLL groups were 129 6 43 minutes vs 104 6 43 minutes and 9.6 6 5.2 minutes vs 8.3 6 5.0 minutes, respectively (both P 5 NS). There was a significant difference in procedure and fluoroscopy times within the SDL group between the first and second halves of the series, probably secondary to a learning curve. Acute HBP thresholds were higher with SDL than with LLL (2.6 6 1.5 V vs 1.5 6 1.2 V; P 5 .02) and remained stable at 8.4 6 5.3 months. Both SDLs exhibited similar pacing thresholds. Two crossovers between groups occurred (1 in each group). Four patients with SDL and 1 patient with LLL exhibited high thresholds during follow-up. CONCLUSION Permanent HBP using stylet-driven, active-fixation leads delivered through conventional CS sheaths is feasible. Procedural characteristics and lead performance were clinically acceptable.

Background: Arterial blood gases (ABGs) are often sampled incorrectly, leading to a ‘mixed’ or venous sample. Delays in analysis and air contamination are common. Objectives: We measured the effects of these errors in patients with chronic obstructive pulmonary disease (COPD) exacerbations and controls. Methods: Arterial and venous samples were analyzed from 30 patients with COPD exacerbation and 30 controls. Venous samples were analysed immediately and arterial samples separated into non-air-contaminated and air-contaminated specimens and analysed at 0, 30, 60, 90 and 180 min. Results: Mean venous pH was 7.371 and arterial pH was 7.407 (p < 0.0001). There was a correlation between venous and arterial pH (r = 0.5347, p < 0.0001). The regression equation to predict arterial pH was: arterial pH = 4.2289 + 0.43113 · venous pH. There were no clinically significant differences in arterial PO₂ associated with analysis delay. A statistically significant decline in pH was detected at 30 min in patients with COPD exacerbation (p = 0.0042) and 90 min in controls (p < 0.0001). A clinically significant decline in pH emerged at 73 min in patients with COPD exacerbation and 87 min in controls. Air contamination was associated with a clinically significant increase in PO₂ in all samples, including those that were immediately analyzed. Conclusions: Arterial and venous pH differ significantly. Venous pH cannot accurately replace arterial pH. Temporal delays in ABG analysis result in a significant decline in measured pH. ABGs should be analysed within 30 min. Air contamination leads to an immediate increase in measured PO₂, indicating that air-contaminated ABGs should be discarded.

Sleep apnea has been recognized as a factor predisposing to atrial fibrillation recurrence and progression. The effect of other sleep-disturbing conditions on atrial fibrillation progression is not known. We sought to determine whether frequent periodic leg movement during sleep is a risk factor for progression of atrial fibrillation. In this retrospective study, patients with atrial fibrillation and a clinical suspicion of restless legs syndrome who were referred for polysomnography were divided into two groups based on severity of periodic leg movement during sleep: frequent (periodic movement index >35/h) and infrequent (≤35/h). Progression of atrial fibrillation to persistent or permanent forms between the two groups was compared using Wilcoxon rank-sum test, chi-square tests and logistic regression analysis. Of 373 patients with atrial fibrillation (77% paroxysmal, 23% persistent), 108 (29%) progressed to persistent or permanent atrial fibrillation during follow-up (median, 33 months; interquartile range, 16-50). Compared to patients with infrequent periodic leg movement during sleep (n=168), patients with frequent periodic leg movement during sleep (n=205) had a higher rate of atrial fibrillation progression (23% vs. 34%; p=0.01). Patients with frequent periodic leg movement during sleep were older and predominantly male; however, there were no significant differences at baseline in clinical factors that promote atrial fibrillation progression between both groups. On multivariate analysis, independent predictors of atrial fibrillation progression were persistent atrial fibrillation at baseline, female gender, hypertension and frequent periodic leg movement during sleep. In patients with frequent periodic leg movement during sleep, dopaminergic therapy for control of leg movements in patients with restless legs syndrome reduced risk of atrial fibrillation progression. Frequent leg movement during sleep in patients with restless legs syndrome is associated with progression of atrial fibrillation to persistent and permanent forms.

The off-label use of chelation therapy (disodium edetate or EDTA) for prevention of cardiovascular disease (CVD) is widespread, despite the lack of convincing evidence for efficacy or approval from the Food and Drug Administration. After the publication of results from the National Institute of Health-sponsored Trial to Assess Chelation Therapy (TACT), a randomized controlled trial (RCT) in patients after myocardial infarction (MI), there is a renewed interest in clarifying the role of this treatment modality for patients with coronary artery disease. Areas covered: This narrative review highlights the evidence from observational studies and RCT in assessing the effect of chelation therapy on cardiovascular outcomes and potential for adverse effects or harm. Expert commentary: Although encouraging results were reported in TACT, the evidence is insufficient to recommend the routine use of chelation therapy even in the post-MI diabetic subgroup, which appeared to benefit. The ongoing TACT2 trial may clarify its use in post-MI diabetic patients. Unsubstantiated claims of chelation therapy as an effective treatment of atherosclerosis should be avoided and patients made aware of the inadequate evidence for efficacy and potential adverse effects, especially the harm that can occur if used as a substitute for proven therapies.