Biomarkers of Metabolic Syndrome: Role in Pathogenesis and Pathophysiology Of Atrial Fibrillation

Up-regulated small-conductance calcium-activated potassium currents contribute to atrial arrhythmogenesis in high-fat feeding mice

AIMS

Metabolic syndrome (MetS) is associated with arrhythmias and cardiovascular mortality. Arrhythmogenesis in MetS results from atrial structural and electrical remodelling. The small-conductance Ca2+-activated K+ (SK) currents modulate atrial repolarization and may influence atrial arrhythmogenicity. This study investigated the regulation of SK current perturbed by a high-fat diet (HFD) to mimic MetS.

METHODS AND RESULTS

Thirty mice were divided into two groups that were fed with normal chow (CTL) and HFD for 4 months. Electrocardiography and echocardiography were used to detect cardiac electrical and structure remodelling. Atrial action potential duration (APD) and calcium transient duration (CaTD) were measured by optical mapping of Langendorff-perfused mice hearts. Atrial fibrillation (AF) inducibility and duration were assessed by burst pacing. Whole-cell patch clamp was performed in primarily isolated atrial myocytes for SK current density. The SK current density is higher in atrial myocytes from HFD than in CTL mice (P ≤ 0.037). The RNA and protein expression of SK channels are increased in HFD mice (P ≤ 0.041 and P ≤ 0.011, respectively). Action potential duration is shortened in HFD compared with CTL (P ≤ 0.015). The shortening of the atrial APD in HFD is reversed by the application of 100 nM apamin (P ≤ 0.043). Compared with CTL, CaTD is greater in HFD atria (P ≤ 0.029). Calcium transient decay (Tau) is significantly higher in HFD than in CTL (P = 0.001). Both APD and CaTD alternans thresholds were higher in HFD (P ≤ 0.043), along with higher inducibility and longer duration of AF in HFD (P ≤ 0.023).

CONCLUSION

Up-regulation of apamin-sensitive SK currents plays a partial role in the atrial arrhythmogenicity of HFD mice.

Ceramides and metabolic profiles of patients with acute coronary disease: a cross-sectional study

Metabolic Syndrome (MS) is a rapidly growing medical problem worldwide and is characterized by a cluster of age-related metabolic risk factors. The presence of MS increases the likelihood of developing atherosclerosis and significantly raises the morbidity/mortality rate of acute coronary syndrome (ACS) patients. Early detection of MS is crucial, and biomarkers, particularly blood-based, play a vital role in this process. This cross-sectional study focused on the investigation of certain plasma ceramides (Cer14:0, Cer16:0, Cer18:0, Cer20:0, Cer22:0, and Cer24:1) as potential blood biomarkers for MS due to their previously documented dysregulated function in MS patients. A total of 695 ACS patients were enrolled, with 286 diagnosed with MS (ACS-MS) and 409 without MS (ACS-nonMS) serving as the control group. Plasma ceramide concentrations were measured by LC-MS/MS assay and analyzed through various statistical methods. The results revealed that Cer18:0, Cer20:0, Cer22:0, and Cer24:1 were significantly correlated with the presence of MS risk factors. Upon further examination, Cer18:0 emerged as a promising biomarker for early MS detection and risk stratification, as its plasma concentration showed a significant sensitivity to minor changes in MS risk status in participants. This cross-sectional observational study was a secondary analysis of a multicenter prospective observational cohort study (Chinese Clinical Trial Registry, https://www.who.int/clinical-trials-registry-platform/network/primary-registries/chinese-clinical-trial-registry-(chictr), ChiCTR-2200056697), conducted from April 2021 to August 2022.

Metabolic Syndrome and Atrial Fibrillation: Different Entities or Combined Disorders

Obesity, hypertension, insulin resistance, and dyslipidemia are all clusters of an entity called "Metabolic Syndrome". The global trends of this syndrome's incidence/prevalence continue to increase reciprocally, converting it into a massive epidemic problem in the medical community. Observing the risk factors of atrial fibrillation, a medical condition that is also converted to a scourge, almost all parts of the metabolic syndrome are encountered. In addition, several studies demonstrated a robust correlation between metabolic syndrome and the occurrence of atrial fibrillation. For atrial fibrillation to develop, a combination of the appropriate substrate and a trigger point is necessary. The metabolic syndrome affects the left atrium in a multifactorial way, leading to atrial remodeling, thus providing both the substrate and provoking the trigger needed, which possibly plays a substantial role in the progression of atrial fibrillation. Due to the remodeling, treatment of atrial fibrillation may culminate in pernicious sequelae, such as repeated catheter ablation procedures. A holistic approach of the patient, with simultaneous treatment of both entities, is suggested in order to ensure better outcomes for the patients.

A Pilot Study of Associations Between the Occurrence of Palpitations and Cytokine Gene Variations in Women Prior to Breast Cancer Surgery

OBJECTIVES

Palpitations are common and have a negative impact on women's quality of life. While evidence suggests that inflammatory mechanisms may play a role in the development of palpitations, no studies have evaluated for this association in patients with breast cancer who report palpitations prior to surgery. The purpose of this pilot study was to evaluate for associations between the occurrence of palpitations and single nucleotide polymorphisms (SNPs) in genes for pro- and anti-inflammatory cytokines, their receptors, and transcriptional regulators.

METHODS

Patients were recruited prior to surgery and completed a self-report questionnaire on the occurrence of palpitations. Genotyping of SNPs in cytokine genes was performed using a custom array. Multiple logistic regression analyses were done to identify associations between the occurrence of palpitations and SNPs in fifteen candidate genes.

RESULTS

Of the 82 SNPs evaluated in the bivariate analyses, eleven SNPs in 6 genes were associated with the occurrence of palpitations. After controlling for functional status, the occurrence of back pain, and self-reported and genomic estimates of race/ethnicity, 3 SNPs in 3 different genes (i.e., interleukin (IL) 1-beta (IL1B) rs1143643, IL10 rs3024505, IL13 rs1295686) were associated with the occurrence of palpitations prior to surgery (all p ≤ .038).

CONCLUSIONS

While these preliminary findings warrant replication, they suggest that inflammatory mechanisms may contribute to the subjective sensation of palpitations in women prior to breast cancer surgery.

Higher serum tissue inhibitor of metalloproteinase-1 predicts atrial fibrillation recurrence after radiofrequency catheter ablation

Background

Tissue inhibitor of metalloproteinase-1 (TIMP-1) levels is strongly associated with cardiac extracellular matrix accumulation and atrial fibrosis. Whether serum levels of TIMP-1 are associated with atrial fibrillation (AF) recurrence following radiofrequency catheter ablation (RFCA) remains unknown.

Materials and methods

Serum TIMP-1 levels of patients with AF before they underwent initial RFCA were measured using ELISA. Univariate and multivariate-adjusted Cox models were constructed to determine the relationship between TIMP-1 levels and AF recurrence. Multivariate logistic regression analyses were performed to determine predictors of AF recurrence.

Results

Of the 194 enrolled patients, 61 (31.4%) had AF recurrence within the median 30.0 months (interquartile range: 16.5–33.7 months) of follow-up. These patients had significantly higher baseline TIMP-1 levels than those without AF recurrence (129.8 ± 65.7 vs. 112.0 ± 51.0 ng/ml, P = 0.041). The same was true of high-sensitivity C-reactive protein (3.9 ± 6.0 vs. 1.9 ± 2.8 ng/ml, P = 0.001). When a TIMP-1 cutoff of 124.15 ng/ml was set, patients with TIMP-1 ≥ 124.15 ng/ml had a higher risk of recurrent AF than those with TIMP-1 < 124.15 ng/ml (HR, 1.961, 95% CI, 1.182–2. 253, P = 0.009). Multivariate Cox regression analysis revealed that high TIMP-1 was an independent risk factor for AF recurrence. Univariate Cox regression analysis found that substrate modification surgery does not affect AF recurrence (P = 0.553). Subgroup analysis revealed that female sex, age < 65 years, hypertension (HTN), body mass index (BMI) ≥ 24 kg/m², CHA2DS2-VASc score < 2, HAS-BLED score < 3, and EHRA score = 3 combined with high TIMP-1 level would perform well at predicting AF recurrence after RFCA.

Conclusion

Elevated preoperative TIMP-1 levels are related to a higher risk of AF recurrence and can independently predict AF recurrence following RFCA.