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When anterior epicardial fat . . . generates Q waves . . . diagnosis of ASMI gets busted !

Posted Apr 24 2013 12:00am

Q wave are  neither  sacred  nor sinister waves . It represents   either of the  following .

Here is young women of 42 years with  a diagnosis of  old  anterior MI for   over 5 years ( Getting a dedicated care from a cardiologist!  The prescription included Imdur/Betaloc/ Statin/Clopidogrel and Aspirin )

This was the ECG . It was very convincing for  old ASMI.

epicardial fat and poor r wave in v 1 v 2 v3 q  waves

It  happened ,  I did an echo for her .

epicardial fat and q waves in ecg pesudo infarct non infarct 2  q

She lacked wall motion defects even after a meticulous search .  Instead   she had a   good layer of epicardial fat measuring 9 mm .That was more localised in  anterior wall extending little to LV apex.Her EF 65 % .

*She was a  fairly obese (not gross )  individual with a BMI of 34 .The fat pad thickness was not that huge  , I thought , still it was producing the q waves . I  have seen much thicker fat pads with good R waves in ECG . I  wonder ,  is it the type of fat that adds up to electrical insulation ?

This patient was sent back to me  again  for ruling out ASMI .  Echo was  done  two weeks  later . No evidence for  ASMI  could be detected.

epicardial fat and q waves in ecg pesudo infarct non infarct fat 2  q

What is the normal thickness of epicardial fat pad ?

It is less than few mm . Exact normality is not known .(Empirically < 5mm ) it is very rare for fat deposition  in infero posterior aspect , except in morbid obesity.

What is the function of epicardial fat ?

  • Long considered inert . Now , found to be a metabolically  active lipid pool.
  • We also know  heart  consumes more fatty acid than an other organs for moment to moment energy consumption .
  • Inflammatory mediator in atherosclerosis ?
  • It may also act as a mechanical cushion effect along with pericardium
  • Rarely fat infiltration can compress the heart and may result in restrictive  AV filling defects in doppler  .(May explain the unexpanded dyspnea  in many obese patients )

Subcutaneous vs  Epicardial fat.

We know thick chest wall can also interfere with ECG. Epicardial fat is more likely to record  q waves than  sub cutaneous fat ,  as the insulation is more closer to heart in epicardial fat . In thick chest wall current leaks from heart and  well scattered  hence  poor R wave is more common in such situations rather than q waves !

Following things can generate  q waves (Other than Infarct  )

Final message

In obese men and women  anterior Q wave can be  misleading .Such  medical errors can be so convincing .

After thought

If epicardial fat can  extiguish a  R wave  and  replace it with a q , these  innocuous  looking fat pads has every reason to  influence the ST segment shifts during a episode of ACS  as well !  .  Isn’t ?   Then  . . . how reliable is  our ECG criterias  to diagnose  acute coronary syndromes  in grossly obese men and women ?

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