wide complex ecgs : case presentation
DESCRIPTION
TRANSCRIPT
LEFT BUNDLE BRANCH BLOCK
SYED RAZA
Prevalence
• 0.2% of large population of US airforce personnel
• 0.6% of population recruited in Framingham Study ( average age 49 years)
• 1-2% in patients above 60 years
CAUSES OF LBBB
Acute myocardial infarction (50%) Underlying significant coronary artery disease• Aortic stenosis • Cardiomyopathy : DCM & HCM• Primary disease of the cardiac electrical
conduction system• Long standing hypertension
Transient LBBB
• Tachycardia• Exercise induced• Acute pulmonary embolism• Heart failure• Coronary vessel fistula
Mechanism
• LBBB itself is related to heart rate acceleration.• When the heart rate quickens, the R-R interval
becomes progressively shorter and a descending impulse may find the left bundle branch still in its refractory period. A “block” is then registered.
• The rate at which conduction changes is called the “critical rate’’
• It will persist until the cycle lengthens enough for normal conduction to occur.
CLINICAL IMPLICATION
• Complete cardiac evaluation as required• Basis for thrombolysis if new in presence of
chest pain• Poor prognosis in patients of heart failure• Cause for inter ventricular dysynchrony and
need for Bi-Ventricular pacemaker• Permanent Pacemaker Implantation if patient
has symptoms of syncope/pre-syncope
Treatment and outcomes of left bundle-branch block patients with myocardial infarction who present without chest pain Michael G. Shlipak, MD, MPH* , Alan S. Go, MD , Paul D. Frederick, MPH, MBA , Judith Malmgren, PhD , Hal V. Barron, MD, FACC ||, John G. Canto, MD, MSPH, FACC¶ for the National Registry of Myocardial Infarction 2 Investigators
•San Francisco VA Medical Center, San Francisco, California, USA
J Am Coll Cardiol, 2000; 36:706-712© 2000 by the American College of Cardiology Foundation
Clinical Implications
• Common in old age, diabetics and female• In patient mortality higher for patients of MI
with LBBB• Mortality is 50% higher for patients who do
not present with chest pain but later diagnosed as MI (under recognised, late diagnosis, no reperfusion therapy, under treated)
SGARBOSSA CRITERIA
Sgarbossa scores >= 3 have a low sensitivity and high specificity for predicting MI in bundle branch block
1.) = or > 1 mm of concordant ST-elevation (in the same direction as the majority of the QRS complex) in at least one lead - (5 points)2.) = or > 1 mm of ST-depression in lead V1, V2 or V3 – (3 points)3.) = or > 5 mm of discordant ST-elevation – (2 points)
