Dr.S.Venkatesan MD

Ventricular  fibrillation is the most dreaded cardiac  arrhythmia  during  STEMI .If  it occurs  outside the hospital , it is usually a  farewell arrhythmia to most  patients . If it occurs within CCU , it is a well tackled arrhythmia  and has  little impact on long term mortality.

When it occurs in early hours of STEMI it is referred  to as primary VF.

Even though it is a killer arrhythmia ,   primary VF is  often  an  one time re- perfusion arrhythmia. There is no entity called recurrent primary VF  .

If recurrent VF occurs some other mechanism is to be suspected (Drug, hypoxia, scar, ion channel defect etc)

Mechanism

Primary VF is ischemia triggered and secondary  VF is  infarct area triggered .Hypoxia ,  LVF or old  scars  also could  contribute .

How to terminate primary VF ?

Immediate defibrillation  is the only option.

After a successful reversion of VF should we follow it up with anti arrhythmic drugs routinely ?

No . It is not routine.(This is  what  we are debating today !)

What if ,  multiple VPDs  and  non sustained VT  continue to occur in the ensuing hours after an episode of   primary VF ?

It is indeed  appropriate ,   to use an infusion of Amiodarone or lignocaine  in such situation . Following  it with oral Amiodarone is generally not required if the LV function is well-preserved.

Advantage and disadvantages of Amiodarone

• Pro arrhythmia – A undermined issue.
• Myocardial depressive action of Amiodarone is a deterrent  for its routine use.
• Amiodarone induced bradycardia (If it is not a AV block )  may be an  advantage  as MVO2  may be reduced.

By the  way , Lignocaine  how  does it fare vis-a-vis Amiodarone ?

It is equally a good drug  with less side effects .But  the  ALIVE  study delivered a  death knock for this wonder drug. Many (At-least me !)   would still   believe  the unpopularity of    Lignocaine  among the    current generation   cardiologists   is  not due to   academic reasons .

So what is the final message  ?

• Even though  popular  opinion and ( even some guidelines )  suggest  it may not be  necessary to give anti arrhythmic drugs  after successful reversion of primary  VF . It is prudent  to weigh  the risks. We can’t use it as  a routine .
• Still , it is always   wiser to prevent further episodes of VF (Rare though ) .
• If you have a well  performing   CCU , routine  post shock Amiodarone is not advised .
• If you do not trust your CCU staff  one may  have to rely on  these drugs.
•  Patients with complicated MI ,  high risk VPDs ( Akin to after shocks after an earth quake ! ) especially in large anterior MIs should receive intensive anti-arrhythmic  therapy (IV followed by oral )

Please note 

**Never plan  for an ICD in patient’s with primary  VF it is an absolute  contraindication.

***Recurrent VT/VF in the setting of STEMI  is  often  termed as electrical storm .It is a rare event which will require immediate CABG/PCI with VT ablation. Again ICDs are  contraindicated  here as the battery depletion will be fast .Further ICDs  it does not cure the VT rather it allows it to emerge from within and then try to tackle it,    while RF ablation eliminates VT focus and prevents it,s origin and provide a potential cure. But , remember only 20%  of VT are amenable for RF ablation ,  while ICD counters all VTs wherever it originates . So there is a role for combination of ablation and then putting an  ICD .