Cardiac causes of ST-Segment Elevation - Dr. L. Littmann

I. Myocardial injury

• In inferior MI, if ST elevation in lead III is greater than ST elevation in II: probable RCA occlusion
  • higher risk of bradycardia, AV block, atrial fibrillation and RV infarct (always with RCA MI)
• In inferior MI, if ST elevation in lead II is greater than ST elevation in III: probable LCX occlusion
  • higher risk of papillary muscle dysfunction, acute mitral regurgitation, pulmonary edema
• Presence of wide and deep Q waves suggests large transmural MI and no viability
  • in acute MI: probable late presentation, no viability
  • in remote MI: consider LV aneurysm
  • In acute anterior STEMI, new right bundle branch block suggests large MI and high mortality
• Acute myocarditis can present with STEMI picture in the ECG
  • clinical presentation is different (severe acute heart failure, pulmonary edema)
  • ST elevation is frequently diffuse
  • conduction abnormalities (A-V block) are frequently present

 

II. Secondary ST-segment elevation

• With wide QRS complexes (left bundle branch block, ventricular pacing, WPW)
  • QRS and ST-Ts are usually discordant: discordant ST elevation is normal
  • ST elevation that is concordant with the QRS complexes strongly suggests STEMI
• In severe LVH with narrow QRS complexes
  • QRS/ST-Ts are usually discordant: ST elevation in the anterior chest leads may be normal
  • in questionable cases, compare with old ECGs; perform serial ECGs; stat bedside echo

 

III. Terminal notching of the QRS complexes followed by hammock-shaped ST elevation

• Pericarditis
  • tachycardia
  • ST elevation is diffuse but usually spares leads aVR and V1
  • depressed PR segment in lead I; elevated PR segment in lead aVR
• Hypothermia
  • bradycardia
  • large and diffuse terminal QRS notching (Osborn waves)
  • prolonged QT
  • shivering artifact
• Benign early repolarization
  • frequently present in young African-American males
  • terminal QRS notch and hammock-shaped ST elevation usually best seen in V4
  • heart rate and QT are usually normal
  • concern about risk of ventricular arrhythmia and sudden death in certain small subgroups

 

IV. Brugada syndrome, Brugada sign

• High take-off upward convex (“coved”) ST elevation followed by negative T waves in V1 and V2
• Increased risk of sudden cardiac death
• Endemic in South-East Asia (Laos, Vietnam, Cambodia, Thailand)
• Male predominance
• Highest risk of sudden death is in patients with resuscitated sudden death, h/o unexplained syncope, spontaneous and dynamic Brugada ECG pattern, nonsustained VT during monitoring
• Most asymptomatic patients without the listed risk factors, especially those who are older at the time of diagnosis, are at minimal risk of unexplained sudden death (“Brugada sign”)

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