Posts Tagged ‘ira localisation algorhythm’

IRA localization for both LAD and RCA , LCX  is a fascinating  exercise for cardiologists.I suspect  our understanding  about this crucial issue is  far from complete .While  localizing  level of lesion within LCA  or RCA requires more precise data and erring is acceptable  , it is not uncommon to  call  even the  IRA wrong  especially in multi -vessel disease.

Why current   criteria of IRA localisation goes awry many times  ?

The  factors  that operate are not few   . . .  it  runs into a dozen  at least  !

  1. Dominance  is never considered during IRA localization  (A right dominate system can vastly influence the LAD localization  algorithm PLV branches  can protect LV postero- lateral segments in spite of proximal LAD lesions )
  2. The length of  mid LAD   IS  controversial entity ( Traditionally  it refers  to  the  segment  between first major diagonal to second  major diagonal or septal  leads to faulty   coronary mensuration .It is not uncommon to have a  mid LAD measuring few  mm  when  full the full  length of  LAD  is about 15-19cm
  3. Diagonal vs OM  trade off occurs  in every alternate patient which is ignored  !
  4. Ramus  is never considered worthy enough  to be included in the IRA  localization scheme (In spite its presence  in 20 % )
  5. Type of LAD is not given allowance.
  6. Finally &  most importantly these rules of IRA localization will not apply in  the setting of  multivessel  CAD
  7. In the presence of Pre existing CTO
  8. STEMI following chronic stable angina
  9. Extensive collaterals
  10. Re Infarctions
  11. Post CABG etc

Final message

Decide for yourself  . . .  how good is the value of IRA localization  after  considering all the above variable. . It is not a great thing to predict  correctly RCA from LCX in an  inferoposterior MI  with a  70 % accuracy  . (It actually means  20 % accuracy  )    statistically when there are only two options  . . .  we are blindly  right 50% of times   !

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