Dr.S.Venkatesan MD

Exercise stress test is the most commonly used non invasive  diagnostic test for CAD.

It is also useful in the functional capacity evaluation.Even though medical management of CAD is a proven and accepted  method of therapy in CAD . There  is always a   perception  even   among the  cardiologists  medical management  is an inferior form of treatment.  This is primarily due to peer group  pressure rather than based on solid scientific concepts.

What is the effect of medical  management on  the common CAD parameters ?

Relief of angina  . It is a simple , and easy parameter to assess.

Functional capacity . Increased exercise capacity  is a good marker of successful medical therapy

The effect  on stress ischemia could be most objective way to assess the success of medical therapy.

But , unfortunately this does not come in the regular scheme of things  for many  cardiologists following medical  management. If we are able to document reversal of stress  test positivity it could be the ultimate marker of success in medical revascularisation. EST is an approved method of assessment of efficacy of optimal medical  management .Still ,  in day to day cardiology practice this is rarely done for the simple reason the patient often stumbles upon an  interventionist and lands up in a PCI or CABG !

Following  things can happen over EST following medical management

• Complete correction of inducible   ischemia
• Delayed appearance of ST depression with increased exercise capacity
• Duration of ST depression can be reduced
• Convert painful  ischemia into silent ischemia*
• No response **

* Conversion of painful episodes into silent episodes may not be a real success  in physiological terms.But in patient point of view it is .It should be  recalled  even in  CABG  pain relief  is a major clinical  outcome .

** Could be termed as failure of medical management , but there  is a  group of patients who have increased exercise  capacity but still EST is positive

Real world experience of large case studies (Individual communication : Large community based stress test in over 9000 patients ( Gnanavel et all Ganesh clinic Thiruvannamalai ,India ) strongly suggest optimal medical management would indeed reverse exercise induced ST depression.

Why can’t we call medical therapy as a revascularisation procedure ?

Human mind does not accept certain things. Simply swallowing few drugs can never make us believe ( Especially the current generation cardiologists !  )  it can be  equivalent to a PCI/CABG

While , restoration of  TIMI flow ,  %  stenosis , Net luminal gain,  are the popular   scientific parameters fro effective revascularisation , the following are  the  desired outcomes  clinical well being , relief from pain, reduction of plaque volume, plaque stabilisation, maintenance of  collaterals , microvascular patency ,  reduction of recurrent events .The irony in CAD management  is  in many points clinical endpoints can be achieved without mechanical  the above  mechanical end points !( As we learn from the OAT, COURAGE trials where we learn t arterial patency is nothing to do with major  clinical end points )

While PCI and CABG inherently convey they are revascularsation procedures , realistically looking medical  therapy also does improve the vascularisation espcially where it is needed (Micro)

In the overall interest of  CAD community , and with good scientific basis ,  it is vital  to  emphazise medical management of CAD  is  also a  form revascualrisation .It is better to call OMT(Optimal medical therapy )  as medical revascularisation .This will help us  to neutralise the unfair” semantic  advantage” the PCI and CABG enjoys as   revascularisation modalities !

Refer: 1.AVERT study :Atorvastatin equals PCI .2.Regular excercise equivalent to PCI (esc2009)

Final message

Medical management , do reverse  the positive EST in most of the patients provided the drugs are optimally used

Stability provided by  medical management   in coronary micro and macrocircualtion is  often  significant and it can either directly  or indirectly improve coronary perfusion .  attenuate ischemia ,  improve exercise capacity and relieve symptoms. To confirm this , every patient  with medical management should periodically undergo exercise stress testing.

* One may argue , without knowing coronary anatomy  it is dangerous to  assume things and every patient with positive EST should udergo CAG. Yes ,  It may be true, ischemia due to  critical lesions in proximal locations can never be corrected with drugs