Embedded Files
It is important to remember that LBBB and paced rhythms DO NOT obviate the ability to diagnose acute coronary occlusion. Sgarbossa Criteria are very specific and may be used to help identify occlusion MI in patients with LBBB or paced rhythms. This is supported by the ESC guidelines (Ibanez et al., 2017). More recently, Di Marco et al. has also proposed a new Barcelona algorithm the has much greater reported sensitivity and comparable specificity for acute OMI in patients with LBBB. Here is a breakdown:
Sgarbossa Criteria
Sgarbossa Criteria
Sgarbossa criteria can be used to help diagnose AMI in setting of LBBB/paced rhythms
LBBB and RV paced rhythms cause ST-segment & T wave changes that can make identification of acute MI difficult
As in in LBBB, paced rhythms are expected to have ST segment & T wave changes that are discordant to the direction of the QRS complex. This is normal & referred to as the “Rule of Appropriate Discordance”
ST-segment deviations that are concordant (in same direction) to the QRS complex or excessively discordant are abnormal
The criteria are reviewed below:
A. Concordant STE ≥ 1 mm (any single lead) = most specific
B. Concordant STD ≥ 1 mm in V1, V2, or V3 = very specific
C. Discordant STE ≥ 5 mm = Less specific for MI in LBBB (most specific in pacers)
A revised Sgarbossa C rule has been proposed to increase the diagnostic utility of the rule for STEMI. This revised rule replaces the absolute criterion (discordant STE ≥ 5 mm) with a proportional criterion (ST-segment to S-wave ratio ≥ 25%) and has been found to be superior to the original criteria for identifying acute coronary occlusion in LBBB.
Although the Sgarbossa and Modified Sgarbossa criteria are very specific for acute MI, these criteria have low sensitivity
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) is abnormal in any lead
Extends Sgarbossa rule of concordant ST depression in V1-V3 to any other lead
Discordant ST deviation (≥ 1 mm) in low voltage QRS complexes (maximal R or S wave is £ 6 mm)
The BARCELONA algorithm reportedly attained the highest sensitivity and negative predictive values, while maintaining high specificity
While the high sensitivity and specificity of the new Barcelona algorithm are promising, they still need external validation to see if the criteria perform as well after independent assessment
References:
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
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
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
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
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.
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.
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
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.
KEY PEARL:
KEY PEARL:
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!
Click the following link to learn more about international criteria for emergent reperfusion in LBBB and Paced Rhythms
Page updated
Google Sites
Report abuse