I. Myocardial injury
II. Secondary ST-segment elevation
III. Terminal notching of the QRS complexes followed by hammock-shaped ST elevation
IV. Brugada syndrome, Brugada sign
- 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”)