Sex Differences in the Relationship between Abdominal Obesity and Cardiovascular Death in Elderly Patients with Permanent Pacemakers Implantation: A Retrospective Cohort Study.

Objectives: This study aims to investigate the association between waist circumference (WC) and cardiovascular death in patients with permanent pacemakers (PPMs). Methods: This is a retrospective cohort study that enrolled patients who underwent PPM implantation in Fuwai Hospital from May 2010 to April 2014, according to the BIOTRONIK Home Monitoring database. The WC was treated as sex-specific quartiles, and patients were divided into three groups according to body mass index (BMI): normal (≤22.9 kg/m2), overweight (23-24.9 kg/m2), and obese (≥25 kg/m2). Cox proportional hazards models were used to calculate hazard ratios and 95% confidence intervals for cardiovascular death according to WC and BMI in patients. Results: 492 patients with PPMs implantation were analyzed (mean age: 71.9 ± 10.8 years; 55.1% men (n = 271)). Data showed that after a mean follow-up 67.2 ± 17.5 months, 24 (4.9%) patients had experienced cardiovascular death and 71 (14.4%) were cases of all-cause mortality. Men in the third quartile of WC had an HR of 10.67 (Model 4, 95% CI: 1.00-115.21, p trend = 0.04) for cardiovascular death. However, the association disappeared in female patients (Model 4, HR = 3.99, 95% CI: 0.37-42.87, p trend = 0.25). There was no association between BMI and cardiovascular death or all-cause mortality in both male and female patients. Conclusions: Abdominal obesity was associated with an increased risk of cardiovascular death in patients with PPMs, and this relationship was only in male patients.

Electrophysiological parameters and anatomical evaluation of left bundle branch pacing in an in vivo canine model.

INTRODUCTION: Left bundle branch pacing (LBBP), a form of conduction system pacing in addition to His bundle pacing (HBP), can potentially maintain left ventricular electrical synchrony with better sensing and a low and stable capture threshold. METHODS: We performed both HBP and LBBP using a canine model (n = 3; male; weight 30-40 kg). The electrocardiogram (ECG), intracardiac electrogram characteristics, and pacing parameters were compared between HBP and LBBP. The hearts were isolated and stained by Lugol's iodine (5%) to assess the relative locations of the leads in relation to the conduction system. RESULTS: The average potential to ventricle interval was longer with HBP compared to LBBP (26.67 ± 3.06 ms vs 12.67 ± 1.15 ms; P = .002). There were also notable differences in the pacing parameters between HBP and LBBP: R-wave amplitude (2.67 ± 0.42 mV vs 11.33 ± 3.06 mV; P = .008), pacing impedance (423.3 ± 40.4 vs 660.0 ± 45.8; P = .003), and threshold (2.30 ± 0.66 V/0.4ms vs 0.67 ± 0.15 V/0.4 ms; P = .014). The paced morphology of ECG was similar to the intrinsic with HBP while a right bundle branch block pattern was noted with LBBP. The anatomical evaluation revealed the location of the leads and the average lead depth was significantly more with LBBP as compared to HBP (12.33 ± 1.53 mm vs1.83 ± 0.29 mm; P < .0001). Furthermore, with LBBP, the tip of the lead helix was noted to be around the LBB. CONCLUSION: This in vivo canine model study confirms the significant differences between HBP and LBBP. Furthermore, this model provides a precise anatomic evaluation of the location and the depth of the leads in relation to the conduction system.

The value of serum metabolomics analysis in predicting the response to cardiac resynchronization therapy.

OBJECTIVE: To construct a prediction model based on metabolic profiling for predicting the response to cardiac resynchronization therapy (CRT). METHODS: Peripheral venous (PV) and coronary sinus (CS) blood samples were collected from 25 patients with heart failure (HF) at the time of CRT implantation, and PV blood samples were obtained from ten healthy controls. The serum samples were analyzed by liquid chromatography-mass spectrometry (LC-MS). As per the clinical and echocardiographic assessment at the 6-month follow-up, the HF patients were categorized as CRT responders and non-responders. RESULTS: HF patients had altered serum metabolomic profiles that were significantly different from those of the healthy controls. Differential metabolites were also observed between CRT responders and non-responders. A prediction model for CRT response (CRT-Re) was constructed using the concentration levels of the differential metabolites, L-arginine and taurine. The optimal cutoff value of the CRT-Re model was found to be 0.343 by ROC analysis (sensitivity, 88.2%; specificity, 87.5%; Area under curve (AUC) = 0.897, P = 0.002). The concentration levels of the differential metabolites, L-arginine and lysyl-gamma-glutamate, in PV serum were significantly correlated with that in CS serum (r = 0.945 and 0.680, respectively, all P < 0.001). CONCLUSIONS: Our results suggest that serum-based metabolic profiling may be a potential complementary screening tool for predicting the outcome of CRT.

The characteristics of the electrocardiogram and the intracardiac electrogram in left bundle branch pacing.

INTRODUCTION: Left bundle branch pacing (LBBP) has recently been reported to maintain left ventricular electrical synchrony with a low and stable threshold. However, the electrocardiogram (ECG) definitions of LBBP have not been well established. We report four cases to show the characteristics of the ECG and the intracardiac electrogram (EGM) in LBBP. METHODS AND RESULTS: Four patients, two with an atrioventricular block (AVB) and two with left bundle branch block (LBBB), were included in the study. LBBP was performed and the ECGs and EGMs were collected and compared at different pacing outputs. Selective LBBP (S-LBBP) was defined as only capturing the LBB with a typical RBBB morphology and a discrete component between the pacing stimulus and ventricular activation in the EGMs. While nonselective LBBP (NS-LBBP) captured both the LBB and the local myocardium, resulting in a narrow right bundle branch block (RBBB) morphology without the discrete component. The left bundle branch (LBB) potential was recorded in two cases during narrow QRS complex or LBBB correction by selective His bundle pacing and SLBBP (n = 3) was achieved. A constant and shortest stimulus to left ventricular activation time (LVAT) in LBBP was obtained at different pacing outputs. CONCLUSION: The ECG and EGM characteristics of LBBP can be summarized as: 1) RBBB pattern; 2) usually with the LBB potential; 3) SLBBP with specific ECG changes and a discrete component in EGM; and 4) with a constant and shortest stimulus to LVAT at different pacing outputs. Further studies are necessary to confirm these observations.

Time course of current of injury is related to acute stability of active-fixation pacing leads in rabbits.

BACKGROUND: Magnitude of current of injury (COI) consequent to pacemaker lead fixation is recognized as a predictor of acute lead stability. It is unclear whether dynamic monitoring of COI after lead fixation provides additional information beyond a single assessment performed at the time of fixation. OBJECTIVES: This study was aimed to test the hypothesis that the time course of COI is related to acute lead stability. METHODS AND RESULTS: Active fixation leads with fixed screw were anchored to either Langendorff-perfused rabbit hearts endocardially or in vivo hearts epicardially in manners of contact the helix with no rotation, half rotation and full rotation, respectively. Intracardiac electrogram (EGM) was monitored dynamically from onset to resolution of COI, and magnitudes of intrinsic R wave and COI, including ST-segment elevation, ST/R and intracardiac EGM duration (IED), were measured. A digital force gauge was applied to assess lead stability. In vitro, COI in contacted leads was significantly smaller than those in half rotated (p<0.05) and fully rotated leads (p<0.05), and presented most precipitous recovery to baseline (1.5±1.1 min, p<0.05). Half-rotated and fully rotated leads manifested the same magnitude of COI right after placement. However, the time course of COI was significantly longer in fully rotated leads than that in half rotated leads (26.5±2.8 min vs. 5.6±2.0 min, p<0.05). Similar findings were observed in vivo. The time course of COI was significantly correlated with the force needed to detach the lead from myocardium (r = 0. 72, n = 48, p<0.001). CONCLUSIONS: Time course of COI is related to acute lead stability in rabbits. One might be misled by a single assessment of COI magnitude right after lead placement, whereas persistence of COI is likely to be a useful indicator of adequate lead stability.