Diabetes and Endocrine Disorders (Hyperthyroidism/Hypothyroidism) as Risk Factors for Atrial Fibrillation

Association between the systemic immune-inflammation index and outcomes among atrial fibrillation patients with diabetes undergoing radiofrequency catheter ablation

PURPOSE

To investigate the relationship between the incidence of atrial fibrillation (AF) recurrence and the levels of the systemic immune-inflammatory index (SII, platelet × neutrophil/lymphocyte ratio) in patients with AF and diabetes mellitus (DM) undergoing after radiofrequency catheter ablation (RFCA).

PATIENTS AND METHODS

Preoperative SII levels were determined in AF patients with DM undergoing RFCA. Restricted cubic splines were used to determine the correlation between SII and the risk of AF recurrence. Multivariate-adjusted logistic regression models were constructed to determine the relationship between SII levels and AF recurrence. The predictive value of the clinical model and combined with the SII index was estimated by the area under the receiver-operating characteristic curve, net reclassification improvement (NRI), and integrated discrimination improvement (IDI).

RESULTS

A total of 204 patients with AF and DM who underwent RFCA in our hospital were included. Seventy-seven patients had AF recurred during a mean follow-up of 20 months. Restricted cubic spline analysis showed that when SII ≥ 444.77 × 109 /L, there was a positive correlation with the incidence of AF recurrence. In addition, adding the SII to the predictive model for AF recurrence after RFCA in patients with DM and AF could contribute to an increase in C-statistics (0.798 vs. 0.749, p = .034). After SII was incorporated into the clinical model, the comprehensive discrimination and net reclassification tended to improve (IDI and NRI > 0, p < .05).

CONCLUSION

SII was independently and positively associated with recurrence after the first catheter ablation in patients with DM and AF.

Obesity and atrial fibrillation: a narrative review from arrhythmogenic mechanisms to clinical significance

The prevalence of obesity and atrial fibrillation (AF), which are inextricably linked, is rapidly increasing worldwide. Obesity rates are higher among patients with AF than healthy individuals. Some epidemiological data indicated that obese patients were more likely to develop AF, but others reported no significant correlation. Obesity-related hypertension, diabetes, and obstructive sleep apnea are all associated with AF. Additionally, increased epicardial fat, systemic inflammation, and oxidative stress caused by obesity can induce atrial enlargement, inflammatory activation, local myocardial fibrosis, and electrical conduction abnormalities, all of which led to AF and promoted its persistence. Weight loss reduced the risk and reversed natural progression of AF, which may be due to its anti-fibrosis and inflammation effect. However, fluctuations in weight offset the benefits of weight loss. Therefore, the importance of steady weight loss urges clinicians to incorporate weight management interventions in the treatment of patients with AF. In this review, we discuss the epidemiology of obesity and AF, summarize the mechanisms by which obesity triggers AF, and explain how weight loss improves the prognosis of AF.

Electrochemical immunoassay for one-pot detection of thyroxin (T4) and thyroid-stimulating hormone (TSH) using magnetic and Janus nanoparticles

Concurrent measurement of thyroid-stimulating hormone (TSH) and thyroxine (T4) hormones profoundly help clinicians diagnose hyper- and hypothyroidism. This work demonstrates the development of a sandwich-type electrochemical immunoassay using Janus and magnetic nanoparticles for one-pot detection of thyroxine (T4) and thyroid-stimulating hormone (TSH). The signaling probe was developed by preparing Janus cadmium (CdO) and zinc oxide (ZnO) NPs decorated by T4/TSH-specific molecularly imprinted polymers (MIP_T4-CdO and MIP_TSH-ZnO). The capture probe was obtained by coating magnetic Fe₃O₄ NPs with 1,3-Bis(3-carboxy propyl) tetramethyl disiloxane and activating using N-hydroxy succinimide (NHS) and 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide (EDC), and finally conjugating with T4/TSH-specific antibodies. To analyze T4 and TSH in actual samples, MIP_T4-CdO and MIP_TSH-ZnO were added to the sample solutions, and after incubation, capture probes (Fe₃O₄-Ab_TSH and Fe₃O₄-Ab_T4) were added. An external magnetic field was used to separate the sandwiched nanosystem, followed by adding a dilute solution of nitric acid (HNO₃) to dissolve CdO and ZnO NPs and free Cd(II) and Zn(II) cations. The concentration of these cations was determined using constant-current potentiometric stripping analysis (cc-PSA) on screen-printed electrodes (SPE) modified with multi-walled carbon nanotubes (MWCNT). The obtained signals for Cd(II) and Zn(II) were proportional to T4 and TSH concentrations. Limits of detection (LOD) for T4 and TSH analyses were respectively 0.02 ng.dL^-1 and 0.0002 µU.mL^-1 with a linear range of 0.05-50 ng.dL^-1 and 0.001-100 µU.mL^-1. The proposed nanosystem's main advantage is the simultaneous detection of T4 and TSH in clinical samples with high sensitivity, selectivity, and stability.

Thyroid hormone disorder and the heart: The role of cardiolipin in calcium handling

NEW FINDINGS

What is the central question of this study? Do alterations in thyroid status affect haemodynamic parameters and echocardiographic measurements in the rat postnatal heart, and calcium handling, contractility, relaxation and cardiolipin content in isolated rat cardiomyocytes? What is the main finding and its importance? An imbalance in phospholipids of the mitochondrial membrane such as cardiolipin is related to defects in mitochondrial function. T3 -dependent cardiolipin signals contribute to the maintenance of mitochondrial homeostasis and involve Ca2+ handling, this pathway being more important in hypothyroidism.

ABSTRACT

The objective of this study was to evaluate whether alterations in thyroid status affect (1) haemodynamic parameters and echocardiographic measurements in the rat postnatal heart, and (2) calcium handling, contractility, relaxation and cardiolipin content in isolated rat cardiomyocytes. Sprague-Dawley rats aged 2 months treated with T3 (hyperthyroid, 20 μg/100 g body weight) or 0.02% methimazole (hypothyroid, w/v) for 28 days. Heart function was evaluated by echocardiography. Measurements of mean arterial pressure (MAP), heart rate, Ca2+ transients, cardiomyocyte shortening, number of spontaneous contractions per minute and cardiolipin (CL) content were performed. Thyroid disorders were associated with changes in pacemaker activity without modifications of MAP. Thyroid disorder induced changes in left ventricular diameter which were correlated with modifications of cardiac contractility (altered cell shortening and sarcoplasmic reticulum Ca2+ content). Endocrine disorders altered cardiomyocyte relaxation (reduction in the time to 50% re-lengthening and the time to 50% Ca2+ decay). Thyroid disorder increased the number of spontaneous contractions per minute (an index of pro-arrhythmogenic behaviour). CL content was increased only in hypothyroid rats. Changes in CL content, CL composition and CL-protein interaction in mitochondria from hypothyroid animals are responsible for alterations of contractile and relaxation cardiac function. This mechanism may be not be involved in T3 -treated rats. Maintenance of euthyroidism is of crucial importance to preserve cardiac performance. An imbalance in relation to phospholipids of the mitochondrial membrane such as CL is related to defects in mitochondrial function. T3 -dependent CL signals contribute to the maintenance of mitochondrial homeostasis and involve Ca2+ handling, this pathway being more important in hypothyroidism.

Gender difference in association between diabetes mellitus and all-cause mortality in atrial fibrillation patients

OBJECTIVE

There may be gender difference in correlation of diabetes mellitus (DM) and cardiovascular events. We attempt to investigate whether there is gender-heterogeneity in one-year outcomes of atrial fibrillation (AF) patients with DM or not.

METHODS

Patients who were diagnosed with AF admitted to the emergency departments in the Chinese AF Multicenter Registry study were enrolled. Basic demographics information, initial Blood Pressure and heart rate, medical histories, and treatments of each patient were collected. Follow-up was carried out with a mean duration of one year. The primary endpoint was all-cause mortality and systemic embolism.

RESULTS

A total of 2016 patients were selected from September 2008 and April 2011. All-cause mortality was significantly higher in male AF patients with DM than those without (21.8 % & 13.6 %, P = 0.014). Cox regression analysis showed that there was an interaction between gender and DM for one-year all-cause mortality (P = 0.049). DM was significantly associated with one-year all-cause mortality regardless of univariate analysis (HR = 1.436, 95%CI:1.079-1.911, P = 0.013) or multivariate analysis (HR = 1.418, 95%CI: 1.059-1.899, P = 0.019). For male patients with AF, DM was significantly associated with one-year all-cause mortality (P = 0.048), but not for female patients with AF (P = 0.362).

CONCLUSION

DM was independently associated with one-year all-cause mortality in the entire cohort of AF patients. This association was found mainly in male patients with AF, but not in female patients. DM management programs may need to reflect gender difference.

Identification of atrial-enriched lncRNA Walras linked to cardiomyocyte cytoarchitecture and atrial fibrillation

Atrial fibrillation (AF) is the most prevalent cardiac arrhythmia in humans. Genetic and genomic analyses have recently demonstrated that the homeobox transcription factor Pitx2 plays a fundamental role regulating expression of distinct growth factors, microRNAs and ion channels leading to morphological and molecular alterations that promote the onset of AF. Here we address the plausible contribution of long non-coding (lnc)RNAs within the Pitx2>Wnt>miRNA signaling pathway. In silico analyses of annotated lncRNAs in the vicinity of the Pitx2, Wnt8 and Wnt11 chromosomal loci identified five novel lncRNAs with differential expression during cardiac development. Importantly, three of them, Walaa, Walras, and Wallrd, are evolutionarily conserved in humans and displayed preferential atrial expression during embryogenesis. In addition, Walrad displayed moderate expression during embryogenesis but was more abundant in the right atrium. Walaa, Walras and Wallrd were distinctly regulated by Pitx2, Wnt8, and Wnt11, and Wallrd was severely elevated in conditional atrium-specific Pitx2-deficient mice. Furthermore, pro-arrhythmogenic and pro-hypertrophic substrate administration to primary cardiomyocyte cell cultures consistently modulate expression of these lncRNAs, supporting distinct modulatory roles of the AF cardiovascular risk factors in the regulation of these lncRNAs. Walras affinity pulldown assays revealed its association with distinct cytoplasmic and nuclear proteins previously involved in cardiac pathophysiology, while loss-of-function assays further support a pivotal role of this lncRNA in cytoskeletal organization. We propose that lncRNAs Walaa, Walras and Wallrd, distinctly regulated by Pitx2>Wnt>miRNA signaling and pro-arrhythmogenic and pro-hypertrophic factors, are implicated in atrial arrhythmogenesis, and Walras additionally in cardiomyocyte cytoarchitecture.

PRRX1 Loss-of-Function Mutations Underlying Familial Atrial Fibrillation

Background

Atrial fibrillation (AF) is the most common form of clinical cardiac dysrhythmia responsible for thromboembolic cerebral stroke, congestive heart failure, and death. Aggregating evidence highlights the strong genetic basis of AF. Nevertheless, AF is of pronounced genetic heterogeneity, and in an overwhelming majority of patients, the genetic determinants underpinning AF remain elusive.

Methods and Results

By genome‐wide screening with polymorphic microsatellite markers and linkage analysis in a 4‐generation Chinese family affected with autosomal‐dominant AF, a novel locus for AF was mapped to chromosome 1q24.2–q25.1, a 3.20‐cM (≈4.19 Mbp) interval between markers D1S2851 and D1S218, with the greatest 2‐point logarithm of odds score of 4.8165 for the marker D1S452 at recombination fraction=0.00. Whole‐exome sequencing and bioinformatics analyses showed that within the mapping region, only the mutation in the paired related homeobox 1 (PRRX1) gene, NM_022716.4:c.319C>T;(p.Gln107*), cosegregated with AF in the family. In addition, sequencing analyses of PRRX1 in another cohort of 225 unrelated patients with AF revealed a new mutation, NM_022716.4:c.437G>T; (p.Arg146Ile), in a patient. The 2 mutations were absent in 908 control subjects. Biological analyses in HeLa cells demonstrated that the 2 mutants had significantly diminished transactivation on the target genes ISL1 and SHOX2 and markedly decreased ability to bind the promoters of ISL1 and SHOX2 (2 genes causally linked to AF), although with normal intracellular distribution.

Conclusions

This study first indicates that PRRX1 loss‐of‐function mutations predispose to AF, which provides novel insight into the molecular pathogenesis underpinning AF, implying potential implications for precisive prophylaxis and management of AF.

Associations of new-onset atrial fibrillation and severe visual impairment in type 2 diabetes: A multicenter nationwide study

BACKGROUND

Many studies have demonstrated an association between type 2 diabetes mellitus (T2DM) and atrial fibrillation (AF). However, the potential independent contributions of T2DM and AF to the prevalence of visual impairment have not been evaluated.

AIM

To determine whether such an association between T2DM and incident AF with visual impairment exists, and if so, the prevalence and magnitude of this association.

METHODS

We conducted a nationwide cross-sectional study based on the DM/HT study of the Medical Research Network of the Consortium of Thai Medical Schools. This study had evaluated adult T2DM patients from 831 public hospitals in Thailand in the year 2013. T2DM patients were categorized into two groups: patients without and with incident AF. T2DM patients without AF were selected as the reference group. The association between incident AF and visual impairment among T2DM patients was assessed using multivariate logistic regression.

RESULTS

A total of 27281 T2DM patients with available eye examination data were included in this analysis. The mean age was 60.7 ± 10.5 years, and 31.2% were male. The incident AF was 0.2%. The prevalence of severe visual impairment in all T2DM patients, T2DM patients without AF, and T2DM patients with incident AF were 1.4%, 1.4%, and 6.3%, respectively. T2DM patients with incident AF were associated with an increased OR of 3.89 (95%CI: 1.17-13.38) for severe visual impairment compared with T2DM patients without AF.

CONCLUSION

T2DM patients with incident AF were independently associated with increased severe visual impairment. Therefore, early eye screening should be provided for these high-risk individuals.