Feeds:
Posts
Comments

Posts Tagged ‘carvidilol vs metoprolol and bisoprolol’

Beta blockers(BBs)  have become  key drugs in  management of CHF .It helps by blocking  toxic effects of inappropriately  elevated   catecholamine  , which is actually a  compensatory response(A fight and survival reaction )  from the sympathetic system  to a failing  heart . This process becomes a liability in the long run  as the  adrenergic receptors either down regulate or even promote apoptosis and cell death .Along with  RASS-ACE  it affects every cell in the body promoting neuro- humoral catabolic state.

By trial and error  methodology we have found blocking the sympathetic system by BBs confer  consistent benefits in CHF .This is in contrary to the days we were ignorantly stimulating the beta receptors with positive inotropic  agents and  wary to give BBs in cardiac failure .This is one the most dramatic 180 degree turn around in the annals of clinical cardiac therapeutics last century.

Is all BBs  same ? Is it the class effect ?

It is tempting to think  all  BBs are  equal and to conclude they simply represent a class effect.But carvidilol  seems to be the flag bearer , for whatever  reason . (Apart from the outcome of  landmark studies , there is a pharmacological basis for it’s superiority COMET/COPERNICUS)

What is the secret of carvidilol’s superiority in CHF than other BBs ?

We know CHF is a systemic syndrome as do the  sympathetic activation .Hence , In CHF , it would require a non selective , systemically acting beta blocker to reverse and reset the adverse  effects of  catechlamine.surge.(Does that mean Propronolol (Inderal ) could be the best ?)

Carvidilol being a non selective BB  fits  perfectly  for the job . Of course , additionally  it has alpha blocking action that reduce the  after-load  reliving he LV wall stress during systole enabling further lowering of MVO2 and   promoting  regression of LV size as well.

Having said  that  prototype cardioselctive agents  like  Metoprolol , Bisoprolol are also  backed by robust evidence  for survival benefit in CHF . How to explain this paradox ? (CIBIS/MERIT )

“Thinking wildly(Evidence  would come later ) it is possible the benefits  from cardio selective agents are  accrued much  later as the dosage is titrated upwards . I would believe the  “inflection point”  of benefit could be same time they lose the cardioselectivity”

Final message

Cardioselectivity is  boasted as a gifted property of BBs .It may be true  in HT, arrhythmia and angina , but  in cardiac  failure it plays a different  ball game .The simple logic is the target  receptors need to be blocked  in systemic fashion.

 Reference

2. http://www.jfponline.com/fileadmin/qhi/jfp/pdfs/6402/JFP_06402_ClinInq1.pdf

Read Full Post »