Atrial Fibrillation Recurrence Prevention after Electrical Cardioversion in High-Risk Patients – Benefits of Non-Antiarrhythmic Drugs

Background:

Recurrence prevention after Atrial Fibrillation (AF) termination by Eelectrical Cardioversion (ECV) remains challenging. Increasing attention is paid to pathophysiological effects of non-Antiarrhythmic Drugs (non-AADs), nevertheless, with heterogeneous results.

Objective:

We evaluated the potential benefits of different non-AADs as adjunctive therapy to Antiarrhythmic Drugs (AADs) for AF recurrence prevention after sinus rhythm restoration by ECV in high-risk patients.

Methods:

The study was conducted among high-risk AF patients after successful ECV. Prescription of class IC or class III AAD was required. Data were acquired in a face-to-face baseline interview and 1-, 3-, 6-, 9-, 12-month follow-up interviews.

Results:

113 patients were included. Total AF recurrence rate reached 48.7%. Angiotensin-Converting Enzyme Inhibitor (ACEI) or angiotensin receptor blocker (ARB) intake, compared with non-use, demonstrated AF recurrence rate reduction by 8.5% (46.3 vs. 54.8%), with odds ratio (OR) reduced by 28.9% (OR 0.711, 95% confidence interval (CI) 0.310-1.631, p = 0.420). Among mineralocorticoid receptor antagonist (MRA) users, AF recurrence rate was reduced by 25.1% (29.6 vs. 54.7%) and OR by 65.1% (OR 0.349, 95%CI 0.138-0.884, p = 0.023). Present statin therapy reduced AF recurrence rate by 4.2% (46.8 vs. 51.0%) and OR by 15.5% (OR 0.845, 95%CI 0.402-1.774, p = 0.656). Diuretic use showed reduction of AF recurrence rate by 10.2% (41.7 vs. 51.9%) and OR by 33.9% (OR 0.661, 95%CI 0.297-1.469, p = 0.308).

Conclusion:

Non-AADs demonstrated practical benefits as adjunctive therapy to AADs for AF recurrence prevention after ECV in high-risk patients, with statistically significant results established for concomitant MRA intake.

Association of furosemide or hydrochlorothiazide use with risk of atrial fibrillation post pacemaker implantation among elderly patients

Background

Atrial fibrillation (AF) induced by artificial pacing is directly related to atrial remodeling. Previous basic research has shown that furosemide aggravates pathologic myocardial remodeling while hydrochlorothiazide alleviates it. However, whether furosemide or hydrochlorothiazide plays a role in developing AF after pacemaker implantation remains unknown. The study aims to investigate the association between oral furosemide or hydrochlorothiazide and the risk of developing AF after pacemaker implantation.

Methods

After a review of electronic medical records, elderly patients with pacemaker implantation and without a known baseline history of AF were included and information on their use of daily oral furosemide or hydrochlorothiazide was extracted. New incident AF cases were confirmed via the records of outpatient visits. A Cox proportional-hazards model was used to evaluate the association between daily oral furosemide or hydrochlorothiazide and risk of developing AF after pacemaker implantation, after adjustment for potential confounders.

Results

Among a total of 551 patients aged more than 65 years, 157 AF cases were identified after pacemaker implantation during a maximum follow up of 3.0±1.6 years. Of these, 242 had used furosemide and 97 had used hydrochlorothiazide therapy. Patients taking daily oral furosemide had a relatively higher risk of AF after pacemaker implantation [hazard ratio (HR): 1.507, 95% confidence interval (CI): 1.036–2.192; P=0.032] after being adjusted for related disease and prescribed medications, while oral taking of hydrochlorothiazide was shown to be a non-effective factor (HR: 0.666, 95% CI: 0.413–1.074), which had no statistical significance.

Conclusions

Daily oral furosemide might increase the risk of developing AF after pacemaker implantation in elderly patients, while hydrochlorothiazide has no detrimental effect.

Relation of Obesity to Outcomes of Hospitalizations for Atrial Fibrillation

Obesity has been linked with increased incidence of atrial fibrillation (AF), but impact of presence of obesity on outcomes of hospitalizations for AF has not been investigated. We used the National Inpatient Sample database 2010 to 2014 to identify all adult hospitalizations aged ≥18years with a primary diagnosis of AF. Obese patients were identified using the co-morbidity variable for obesity, as defined in National Inpatient Sample databases. Multivariable logistic regression was used to compare in-hospital outcomes (mortality, acute stroke events) between obese and non-obese patients with AF. Of 431, 734 hospitalizations for AF, 66,138 (15.3%) were obese. Obese patients were younger and more likely to be African-Americans compared with non-obese patients. Despite being younger, obese patients had significantly higher prevalence of cardiovascular co-morbidities such as hypertension, diabetes mellitus, dyslipidemia, smoking, heart failure, and chronic renal failure (p <0.001 for all). After multivariate risk-adjustment, obese patients had a lower observed in-hospital mortality (0.5% vs 1.0%; unadjusted odds ratio = 0.52, 95% confidence interval [CI] 0.46 to 0.58, p <0.001; adjusted odds ratio = 0.83, 95% CI 0.73 to 0.94, p <0.001) and acute stroke events (0.4% vs 0.7%, unadjusted odds ratio = 0. 65, 95% CI 0.57 to 0.73, p < 0.001; adjusted odds ratio = 0.82, 95% CI 0.72 to 0.94) compared with non-obese patients. In conclusion, in this large retrospective analysis of an unselected nationwide cohort of patients hospitalized for AF, obese patients demonstrated lower risk-adjusted odds of in-hospital mortality and stroke events, consistent with an "obesity paradox."

Functional transient receptor potential canonical type 1 channels in human atrial myocytes

Transient receptor potential (TRP) channels are not well understood in human atrium, and the present study was therefore designed to investigate whether TRPC channels would mediate the nonselective cation current reported previously and are involved in the formation of store-operated Ca(2+) entry (SOCE) channels in human atrial myocytes using approaches of whole-cell patch voltage-clamp, RT-PCR, Western blotting, co-immunoprecipitation, and confocal scanning approaches, etc. We found that a nonselective cation current was recorded under K(+)-free conditions in human atrial myocytes, and the current was inhibited by the TRP channel blocker La(3+). Thapsigargin enhanced the current, and its effect was suppressed by La(3+) and prevented by pipette inclusion of anti-TRPC1 antibody. Endothlin-1 and angiotensin II enhanced the current that could be inhibited by La(3+). Gene and protein expression of TRPC1 channels were abundant in human atria. In addition, mRNA and protein of STIM1 and Orai1, components of SOCE channels, were abundantly expressed in human atria. Co-immunoprecipitation analysis demonstrated an interaction of TRPC1 with STIM1 and/or Orai1. Ca(2+) signaling mediated by SOCE channels was detected by a confocal microscopy technique. These results demonstrate the novel evidence that TRPC1 channels not only mediate the nonselective cation current, but also form SOCE channels in human atria as a component. TRPC1 channels can be activated by endothelin-1 or angiotensin II, which may be involved in the atrial electrical remodeling in patients with atrial fibrillation.