Increasing atrial fibrillation: What is the cause?

A 72‐year‐old woman with a history of paroxysmal atrial fibrillation (AF) and sinus node dysfunction is seen in clinic for routine follow‐up.     

Hyperhomocysteinemia and vitamin B6 deficiency: new risk markers for nonvalvular atrial fibrillation?

Background

A recent “ex-vivo” study showed that nonvalvular atrial fibrillation (NVAF) is associated with enhanced activity of metalloproteinases at the atrial level, and in animal models homocysteine (Hcy) is able to activate metalloproteinases. The aim of this case-control study was to investigate the association of total Hcy plasma levels, vitamin status (folate, vitamin B₆, and vitamin B₁₂), and methylenetetrahydrofolate reductase C677T and CBS 844ins68 polymorphisms with NVAF. Furthermore, the role of these variables in the occurrence of ischemic events was investigated.

Methods

We studied 310 NVAF patients on oral anticoagulant treatment (168 patients with previous ischemic events and 142 without) and 310 controls.

Results

Hyperhomocysteinemia (highest quartile) and vitamin B₆ deficiency (lowest quartile) were independently associated with NVAF after multivariate analysis (Hcy: odds ratio [OR] 6.40, 95% CI 3.29-12.46; vitamin B₆: OR 3.02, 95% CI 1.02-8.95). A significant correlation was found between Hcy levels and left atrial diameter (r = 0.46; P < .001). As shown by multivariate analysis, elevated Hcy levels were an independent risk factor for ischemic complications during NVAF (OR 2.66, 95% CI 1.15-6.20).

Conclusions

This study demonstrates a significant association of both elevated Hcy levels and low vitamin B₆ levels with the presence of NVAF; in addition, it confirms the role of Hcy as a risk factor for ischemic events during NVAF.     

Omega 3 and atrial fibrillation: Where are we?

Anti-arrhythmic properties of n-3 polyunsaturated fatty acids, at least in part mediated by anti-oxidant, anti-inflammatory and anti-fibrotic power, have been widely proved. Effect of fish oil on atrial fibrillation, both in primary and in secondary prevention and after cardiac surgery, are controversial, mostly due to lack of homogeneity between studies but also due to individual variability in response to fatty acids administration. Inclusion of measurement of incorporation of fish oil into cell membranes, appears to be essential in future studies, to assess their antiarrhythmic effect.     

Atrial fibrillation: A progressive atrial myopathy or a distinct disease?

Atrial fibrillation is a complex arrhythmia with multiple possible mechanisms. A lot of experimental and clinical studies have shed light on the pathophysiological mechanisms of arrhythmia, especially on molecular basis. Electrical, contractile and structural remodeling, calcium handling abnormalities, autonomic imbalance and genetic factors seem to play a crucial role in atrial fibrillation initiation and maintenance. However, the exact pathophysiological mechanisms of atrial fibrillation are not completely understood and whether atrial fibrillation is an unclassified cardiomyopathy or a distinct disease still remains to be answered. This review highlights proarrhythmic and pathophysiological mechanisms of atrial fibrillation and approaches the molecular basis underlying atrial fibrillation susceptibility.