Dr.S.Venkatesan MD

The commonest cause of ST elevation is  STEMI .

The non infarct causes of ST elevation include

• Pericarditis
• Early repolarisation syndrome
• Hyperkalemia
• Brugada syndrome
• CNS injury

What is the mechanism of ST eelvation in pericarditis ?

The mechanism of ST elevation in STEMI  is  injury current coming towards the recording lead. In pericarditis  we are not  sure  about the presence of  injury current  because pericardial cells are not  capable of depolarising and repolarsing .But ,  the fact that  epicardium and visceral layer of pericardium are anatomically  are almost same entities .Attempts to rip off visceral pericardium from myocardium ie epicardium is often futile .This makes it very obvious  any true pericarditis  must involve epicardial layers of the heart.

How does inflammation of epicardium  lifts the ST elevation ?

This again is a mystery .The   effect of   inflammation   on the polarity of ST segment  is  complex one. Diffuse and global ST segment elevation with concavity upwards  is the hall mark of pericarditis. This makes us believe pericarditis has to be diffuse  and involve  the entire  circumference of the heart.

Logically and realistically  this happens rarely . Many of the pericarditis are localised and regional . Even regional constrictive pericarditis are reported .The factors that determine the ST elevation in pericarditis  depend on the  spread of the inflammatory process beneath the epicardium .If the inflammation is active  andeep  ST elevation is likely to be  prominent.

The ECG is  that of a 15 year old boy  with a febrile illness .  He developed  severe myopericarditis .The echocardiogram showed  global hypokinesia and severe LV dysfunction .Patient failed to respond  with  medical therapy and succumbed  after 48 hours of onset of shock .

Can we localise pericarditis with the help of ECG ?

It is possible. But there is no clinical purpose to do it.

Can troponin be elevated in pericarditis ?

No it should not happen in pure isolated pericarditis.But , epicardial involvement can result in inflammatory damage  to muscle and troponin can be elevated. When pericarditis occurs as an accompanying manifestation of pancaritis troponin  is bound to elevate (Fulminant pan carditis of acute rheumatic fever)

Final message

Pericarditis need not be diffuse and global infact pathologically it is rare to have global pericarditis  . Localised pericarditis especailly adhesive type , which involves the  posterior  /anterior  epicardial layers can mimic an  either inferior  or anterior  STEMI  . This has important clinical implication as unneccssary coronary interventions can be avoided.

Do not expect  text book descriptions for any ECG pattern in clinical cardiology .

We will be rarely  correct . . .