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The presence of a LBBB or RV paced rhythms (have LBBB pattern) does NOT obviate the ability to diagnose acute occlusion MI. OMI can be detected on the ECG with good specificity!
The presence of a LBBB or RV paced rhythms (have LBBB pattern) does NOT obviate the ability to diagnose acute occlusion MI. OMI can be detected on the ECG with good specificity!
Sgarbossa criteria and the modified Sgarbossa criteria describe ECG findings that may be used to help accurately identify occlusion MI in patients with LBBB or paced rhythms with great specificity. More recently the Barcelona criteria report to have both excellent sensitivity and specificity and are very promising, but still need external validation.
The key is to know what is normal, and look closely for concordant or inappropriately discordant ST deviation in patients with symptoms of acute ischemia!
The use of Sgarbossa Criteria to help identify occlusion MI in patients with LBBB or paced rhythms is supported by the ESC STEMI guidelines (Ibanez et al., 2017):
Bundle branch block
Criteria that can be used to improve the diagnostic accuracy of STEMI in LBBB
Concordant ST segment elevation greater than or equal to 1 mm in leads with a positive QRS complex (most specific)
Concordant ST segment depression greater than or equal to 1 mm in V1-V3 (see: Barcelona)
Discordant ST segment elevation greater than or equal to 5 mm in leads with a negative QRS complex (see: modified Sgarbossa)
The presence of RBBB may confound the diagnosis of STEMI, however STE in RBB is always abnormal
Ventricular paced rhythm
During RV pacing, the ECG also shows LBBB and the above rules also apply for the diagnosis of MI during pacing; however, they are less specific
Acute MI in LBBB Summary:
Acute MI in LBBB Summary:
Know the Sgarbossa criteria, which can and should be applied to LBBB ECG’s where there is concern for acute MI (very specific)
A. Concordant STE ≥ 1 mm in any lead (most specific)
B. Concordant STD ≥ 1 mm in V1, V2, or V3 (very specific)
C. Excessively discordant STE ≥ 5 mm (less specific)
Smith et al. proposed a modified Sgarbossa C criterion that replaces the absolute measurement of STE ≥ 5 mm with a STE/S wave ratio > 25% (more specific than original Sgarbossa C)
Di Marco et al. recently published a new (BARCELONA) algorithm which reportedly has much greater sensitivity and comparable specificity for AMI in LBBB
Concordant ST deviation ≥ 1 mm in any lead
Discordant ST deviation ≥ 1 mm in any lead with a small QRS complex (maximal R or S wave is < 6 mm)
We are awaiting further studies to externally validate modified Sgarbossa and Barcelona criteria
Click the following links to learn more about LBBB, the modified Sgarbossa criteria and Barcelona criteria which have been found to be superior to the original Sgarbossa criteria for identifying acute coronary occlusion in LBBB.
References:
1. Ibanez B, James S, Agewall S, et al. 2017 ESC Guidelines for the management of acute myocardial infarction in patients presenting with ST-segment elevation. Eur Heart J 2017;39(2):119–77. PMID: 28886621.
2. Sgarbossa EB. Recent advances in the electrocardiographic diagnosis of myocardial infarction: left bundle branch block and pacing. Pacing Clin Electrophysiol. 1996;19(9):1370–1379. PMID: 8880802.
2. Sgarbossa EB, Pinski SL, Gates KB, et al. Early electrocardiographic diagnosis of acute myocardial infarction in the presence of ventricular paced rhythm. GUSTO-I investigators. Am J Cardiol. 1996;77(5):423–424. PMID: 8602576.
3. Maloy KR, Bhat R, Davis J, et al. Sgarbossa Criteria are Highly Specific for Acute Myocardial Infarction with Pacemakers. West J Emerg Med. 2010;11(4):354–357. PMID: 21079708.
4. Smith SW, Dodd KW, Henry TD, et al. Diagnosis of ST-Elevation Myocardial Infarction in the Presence of Left Bundle Branch Block With the ST-Elevation to S-Wave Ratio in a Modified Sgarbossa Rule. Ann Emerg Med. 2012;60(6):766–776. PMID: 22939607.
5. Cai Q, Mehta N, Sgarbossa EB, et al. The left bundle-branch block puzzle in the 2013 ST-elevation myocardial infarction guideline: From falsely declaring emergency to denying reperfusion in a high-risk population. Are the Sgarbossa Criteria ready for prime time? American Heart Journal. 2013;166(3):409–413. PMID: 24016487.
6. Pendell Meyers H, Limkakeng AT, Jaffa EJ, et al. Validation of the modified Sgarbossa criteria for acute coronary occlusion in the setting of left bundle branch block: A retrospective case-control study. Am Heart J. 2015;170(6):1255-1264. PMID: 26678648.
7. Di Marco A, Rodriguez M, Cinca J, et al. New Electrocardiographic Algorithm for the Diagnosis of Acute Myocardial Infarction in Patients with Left Bundle Branch Block. J Am Heart Assoc. 2020;9(14):e015573. PMID: 32627643.
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