Friday, June 06, 2014

UNDERSTANDING ATRIAL FIBRILLATION IN 2014

Atrial Fibrillation is the arrhythmia of the decade. In the 70s the focus was on ventricular arrhythmias and much work was done in terms of early monitoring and control. After much research, we concluded that apart from electrical cardioversion or defibrillation, when the malignant rhythm occurs, nothing more can be done. Life style modification was advocated in an attempt to lessen the athrosclerotic burden and so reduce the incidence of ventricular arrhythmias and prevent sudden cardiac death. We also embarked on a program to teach the lay population the art of by-stander basic life support techniques to help salvage those unfortunate ones who may have sudden arrhythmias in public places. Drugs in the control of ventricular arrhythmias proved disappointing as it produce the very arrhythmias that is was suppose to prevent.
In the 21st century, attention was re-directed to less malignant arrhythmias like atrial fibrillation, the atrial equivalent of their ventricular counterpart. However the issue here was not so much sudden cardiac death as sudden brain death, ie strokes. We now have a much better understanding of A.Fib.. However, the initial focus on drug therapy for control only yielded limited success. Anti-arrhythmics to correct A.Fib was disappointing as they all seem to exhibit some pro-arrhythmic effects. Anti-coagulation to reduce the risk of stroke and rate control worked well except that it was fussy and had the side effects of bleeding. However, industry went ahead, and although VKA ( Vit K antagonist ) worked well ( effective ), cheap but fussy, the pharmas are trying to have us all shift to NOAC which are effective, expensive and still have the bleeding risk. The only advantage seem to be less hassle for 3 monthly blood ( PT-INR ) monitoring.
Then came along the Americans with their complex anti-A,Fib maze surgery, slicing up the atrial wall in an attempt to cut off all the routes propagating A.Fib.. This did not sound very sound. Then came along the French who pioneered the initial percutaneous transvenous R.F ablation, which worked quite well, which I have blogged earlier. This is still popular and more and more EP cardiologist are embarking on the program.

However, I believe the answer lies with the Australians. The group from Adelaide, led by Dr Prashanthan Sanders have published two interesting papers on the reduction of A.Fib burden by life style modification. They believe that A.Fib may be related to the traditional coronary risk factors, especially obesity. They first showed that if you make sheep reduce their weight ( BMI ), they have smaller atrial size and smaller risk for A.Fib.  Then they did the same on Humans with A.Fib but were obese and found that when these people lose weight through life style modification, their . Fib load came down. That paper was published in 2013.

Now at the recently concluded Heart Rhythm Socety Annual Scientific Meeting, The Adelaide boys presented their latest paper on this subject. Dr Rajeer Patnak from Dr Sander's unit presented a paper on this subject. They studied 281 patients with A.Fib who were scheduled for A.Fib ablation. 149 of them had BMI > 27 ( obese ). Of these 149 patients, 61 agreed to undergo intensive life style modification under a supervising physician ( Gp1 ), before the ablation. 88 did not agree ( Gp 2 ) and so acted as control. They all underwent successful ablation. After 3 months, 62% of Gp 1 were free from A.Fib recurrence compared to 26% in Gp 2.  After 42 months, following multiple ablations, 87% in Gp1 and 48% in Gp 2 were free of A. Fib after multiple ablations.

Seeing things overall, looks like we do have many choices in the management of  atrial fibrillation. Firstly, in paroxysmal AFib, we could have them on a life style modification, weight reducing diet, hoping that by reducing the size of the LA and the amount of fibrosis in LA, we can reduce the frequency of A.Fib.
In established A Fib, we can rate control them and anticoagulate them noting the benefits according to the CHAD and Modified CHAD score, and also the risk of anticoagulation. I still prefer warfarin although many of my colleagues have gone on to NOAC. My patients do well with warfarin. For established chronic A Fib we can also offer RF ablation, warning them that they may need 2 ablations in 5 years because of the significant risk of recurrence.
Whatever strategy we chose, life style modification can only help ( according to the Australians ) as shown in their work above.

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