wide complex ecgs : case presentation

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)