Management of atrial fibrillation

Clinical risk factors for new-onset atrial fibrillation in acute myocardial infarction: A systematic review and meta-analysis

New-onset atrial fibrillation (NOAF) remains common arrhythmia in acute myocardial infarction (AMI), and is closely associated with increased subsequent cardiovascular mortality. Our meta-analysis aims to summarize more clinical risk factors for NOAF.Comprehensive systematic search of MEDLINE, EMBASE, and the Cochrane Library were carried out to find relevant studies inception to December 2017. Pooled mean difference (MD) and 95% confidence interval (CI) were calculated to evaluate the value of clinical risk factors in the prediction of NOAF after AMI.Eleven studies containing 9570 patients were included in the meta-analysis. Overall, older age and increased heart rate (HR) levels had a significant positive association with NOAF in patients with AMI. The MD in age between the patients with, and those without NOAF, was 8.22 units (95% confidence interval [CI]: 7.44-9.01), test for overall effect z score = 20.51 (P < .00001, I = 0%). Moreover, the MD in a subgroup analysis for HR levels between the patients with, and those without NOAF was 4.34 units (95% Cl: 2.56-6.11), test for overall effect z score = 4.78 (P < .00001, I = 31%).In patient with AMI, our meta-analysis demonstrated that older age and increased HR levels on admission are related to greater risk of NOAF.

Left ventricular ejection fraction and left atrium diameter related to new-onset atrial fibrillation following acute myocardial infarction: a systematic review and meta-analysis

Background

New-onset atrial fibrillation (NOAF) occurs frequently in patients with acute myocardial infarction (AMI), and is associated with increased subsequent cardiovascular mortality. However, only a few studies directly evaluated the relationship of left ventricular ejection fraction (LVEF) or left atrium diameter (LAD) and NOAF following AMI.

Materials and Methods

MEDLINE^®, EMBASE^® and the Cochrane Library were carried out to find studies until January 2017. Pooled mean difference (MD) and 95% confidence interval (CI) were calculated to evaluate the value of LVEF and LAD in the prediction of NOAF after AMI. We performed sensitivity analyses to explore the potential sources of heterogeneity. Statistical analyses were carried out using the Revman 5.3.

Result

We included 10 qualifying studies comprising a total of 708 patients with NOAF and 6785 controls. Overall, decreased LVEF and increased LAD levels had a significant positive association with NOAF in patients with AMI. The MD in the LVEF levels between the patients with and those without NOAF was −4.91 units (95% Cl: −5.70 to −4.12), test for overall effect z-score = 12.18 (p < 0.00001, I² = 35%). Moreover, in a subgroup analysis, the MD for LAD and NOAF was 2.55 units (95% Cl: 1.91 to 3.19), test for overall effect z-score = 7.80 (p < 0.00001, I² = 57%).

Conclusions

Our meta-analysis demonstrated that both decreased LVEF and increased LAD levels were associated with greater risk of NOAF following AMI.

Change in mRNA Expression after Atenolol, a Beta-adrenergic Receptor Antagonist and Association with Pharmacological Response

AIMS: Genetic determinants of variability in response to beta-blockers are poorly characterized. We defined changes in mRNA expression after a beta-blocker to identify novel genes that could affect response and correlated these with inhibition of exercise-induced tachycardia, a measure of beta-blocker sensitivity. METHODS: Nine subjects exercised before and after a single oral dose of 25mg atenolol and mRNA gene expression was measured using an Affymetrix GeneChip Human Gene 1.0 ST Array. The area under the heart rate-exercise intensity curve (AUC) was calculated for each subject; the difference between post- and pre-atenolol AUCs (Delta AUC), a measure of beta-blocker response, was correlated with the fold-change in mRNA expression of the genes that changed more than 1.3-fold. RESULTS: Fifty genes showed more than 1.3-fold increase in expression; 9 of these reached statistical significance (P < 0.05). Thirty-six genes had more than 1.3-fold decrease in expression after atenolol; 6 of these reached statistical significance (P < 0.05). Change in mRNA expression of FGFBP2 and Probeset ID 8118979 was significantly correlated with atenolol response (P = 0.03 and 0.02, respectively). CONCLUSION: The expression of several genes not previously identified as part of the adrenergic signaling pathway changed in response to a single oral dose of atenolol. Variation in these genes could contribute to unexplained differences in response to beta-blockers.

What should be the primary treatment in atrial fibrillation: ventricular rate control or sinus rhythm control with long-term anticoagulation?

Recent trials have favoured ventricular rate control in atrial fibrillation (AF) management, however the present study investigated whether the restoration and maintenance of sinus rhythm with long-term anticoagulation therapy was superior in terms of embolic events and death in 534 patients with an AF duration > 48 h. Patients were randomized and received sinus rhythm control with either aspirin (group 1) or warfarin (group 2), or they were given ventricular rate control (group 3). Cardioversion to sinus rhythm was attempted in 425 patients and was successful in 387 (91.1%) of them. After 3 years' follow-up there were 12, two and 15 embolic events in groups 1, 2 and 3 respectively (significant difference between groups 1 and 2, and 2 and 3) and overall mortalities were four, two and 12, respectively (significant difference between groups 2 and 3). It is concluded that patients with an AF duration > 48 h might benefit considerably from sinus rhythm restoration and long-term warfarin therapy in terms of embolic events and mortality.

Stunning of the Left Atrium after Conversion of Atrial Fibrillation: Predictor for Maintenance of Sinus Rhythm?

Recurrence of atrial fibrillation (AF) after cardioversion (CV) to sinus rhythm (SR) is determined by various clinical and echocardiographic parameters. The aim of this study was to determine the value of mitral inflow A-wave velocity, performed at 24 hours after CV in estimation of AF recurrence. The study group consisted of 187 consecutive patients with nonvalvular atrial fibrillation, who had been cardioverted to SR from 1998 to 2000. Transthoracic echocardiography was performed in all cases recruited for the study 24 hours after CV. Left atrial (LA) diameter, left ventricular ejection fraction, and mitral inflow A-wave velocity were measured. The patients were evaluated in five groups according to their recurrence time (<30 days, 31-90 days, 91-180 days, 181-365 days, and >365 days). Maintenance of SR was determined to have a negative linear correlation with age (r =-0.97, P = 0.006), LA diameter (r =-0.93, P = 0.02), and AF duration (r =-0.93, P = 0.02), while having a positive linear correlation with mitral inflow A-wave velocity (r = 0.96, P = 0.008). In the maintenance of sinus rhythm, age, LA diameter, and AF duration were not affected from the method of CV, while mitral inflow A-wave velocity was found to be affected with the method of CV. No relationship was determined between mitral inflow A-wave velocity and the maintenance of sinus rhythm in those performed electrical cardioversion, while frequency of recurrence was found to be higher in those with slow mitral inflow A-wave velocity who were performed pharmacological cardioversion (r = 0.89, P = 0.004). In conclusion, age, duration of AF, LA diameter, and the mitral inflow A-wave velocity can be used to predict the maintenance of SR after CV.

Comparison of Rate and Rhythm Control in Patients With Atrial Fibrillation and Nonischemic Heart Failure

Atrial fibrillation (AF) is a very common cardiac arrhythmia with an increased mortality in patients with heart failure. Whether the best therapeutic approach to these patients is to restore sinus rhythm or to adequately control the ventricular rate is still controversial. The aim of this study was to compare both strategies in patients with AF and nonischemic heart failure. One hundred and fifty-four patients with AF duration greater than 48 hours and nonischemic left ventricular dysfunction were randomized either to a rhythm (n = 84) or rate (n = 74) control group. The composite end points of the study were embolism, death, and exercise capacity. The average age of the patients was 61 +/- 10 years in the rhythm control group and 58 +/- 12 years in the rate control group (P = NS). The average follow-up period was 35 +/- 21 months in the rhythm control group and 37 +/- 19 months in the rate control group (P = NS). In the first year of the study, exercise capacity and left ventricular ejection fraction (LVEF) were improved in the rhythm control group compared to the exercise capacity and LVEF of the rate control group (P < 0.0001 and P = 0.0005, respectively). There were no statistically significant differences in the embolic event rate between the two groups (P = NS). The mortality rate, especially for death due to pump failure, was significantly higher in the rate control group at the end of the study (P < 0.0001). Restoring and maintaining sinus rhythm had a beneficial effect on mortality and exercise capacity in patients with nonischemic heart failure and AF.