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Posts Tagged ‘beta blcokers in stemi’

Beta blockers are vital drugs  to limit infarct size and  facilitate myocardial salvage. Myocyte death is  prevented by reducing MVO2.These concepts originated in early 1980s when thrombolysis was not in vogue .Studies like MIAMI  and BHAT were considered landmarks.

Later on ,  when IV thrombolysis came in a big way the importance of beta blockade in STEMI  suffered a little ,  still it  held on to their  benefits.

The real problem arose when few enthusiastic cardiologists introduced early multiple blouses of IV beta blockade in the setting of Acute STEMI without realising the potential danger. (In all probability man kind must have lost many thousands  of lives with this aggressive beta blocking protocol world over for nearly a  decade !)

Fortunately  we woke up and in early 2000  , a massive study called COMMIT was  initiated  to answer convincingly the utility value of  routine early IV bet blockade. Rest is history . It clearly showed us the what we were fearing was indeed true. An unacceptably excess cardiogenic shocks were reported in the early IV beta blocker arm .In the same period of time the concept of  primary PCI  exploded and the  BBs were pushed to sidelines

It is a different story  altogether   . . .

While  the funny world of cardiology showed the door for routine early  beta blockers  in STEMI ,  it  made a stunning  U turn   in the management of CHF  , after being dumped as an  absolute contraindication  for so many years !

Still COMMIT  fails to   answer many queries

  • Beta blockers in LBBB /RBBB –     Probably need to be avoided.
  • Beta blockers in bifasicular  block –   Should  be an  absolute contradiction

How do you know  tachycardia  in STEMI is due to high sympathetic activity or cardiac reserve ?

Young men with persistent tachycardia  will do well with beta blocker started within 24  hours .

Unless there is s3 or basal rales all tachycardia are to be considered as purely inappropriate  and  adrenergic

Tachycardia in elderly, women, and diabetic especially the blood pressure hover around 100mmhg is   more often a compensatory  phenomenon.Meddling  the heart rate with BB is vested with a risk.

Finally , if you have a doubt do a rapid echo ,  if the EF is > 45% one can safely administer BBs

Should we discontinue BBs  in those who are already taking it ?

Continuing the beta blocker is  thorough the STEMI phase is adviced .(Unless specific contraindication  exists  )

Beta blocker following primary PCI

The beneficial effect of early Beta blocker even in post thrombolytic era is blunted, it goes without saying primary PCI almost nullifies these effects.

still , beta blockers is to be introduced after a successful primary PCI in all patent for long-term protection.

Final message

Do not rush into start  beta blocker  routinely following STEMI .  The  risk is not worth taking  !

Reference

COMMIT  study from Lancet 2005

ACC/AHA guidelines on Betablocker and STEMI

The following is taken from the above  guidelines   When not to administer IV beta blocker  seems  to be more relevant !

Class 3 recommendation  for  Beta blocker in STEMI (Evidence A)

1. IV beta blockers should not be administered to STEMI patients who have any of the following: 1) signs of heart failure, 2) evidence of a low output state, 3) increased risk* for cardiogenic shock, or 4) other relative contraindications to beta blockade (PR interval greater than 0.24 seconds, second- or third-degree heart block, active asthma, or reactive airway disease). (Level of Evidence: A)

*Risk factors for cardiogenic shock (the greater the number of risk factors present, the higher the risk of developing cardiogenic shock) are age greater than 70 years, systolic blood pressure less than 120 mm Hg, sinus tachycardia greater than 110 bpm or heart rate less than 60 bpm, and increased time since onset of symptoms of STEMI.

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