Collateral Circulation to LAD and Wellens Sign

Introduction Electrocardiograms are an inexpensive and indispensible tool to assess cardiac
rhythm and ischemia. A Wellens sign on an EKG is either a deeply inverted (Type 1) or
biphasic (Type 2) t-wave in precordial leads V2-V3 (but may extend to other precordial
leads). It is associated with critical stenosis of the proximal left anterior descending
(LAD) artery. Patients with a Wellens sign are at high risk for extensive anterior wall
myocardial infarction as the LAD is the main coronary artery that supplies the left
ventricle. Exercise stress testing is contraindicated in this patient population. In
addition, appropriate management of these patients is crucial to avoid acute myocardial
infarction.

There have been a number of studies addressing the role of collateral coronary circulation in
myocardial infarctions. Some studies show that the presence of collateral circulation is
associated with improved in-hospital outcomes in patients following a ST-elevation myocardial
infarction (STEMI) whereas others show that collateral circulation does not decrease
morbidity and mortality in patients following acute STEMI. Similarly, patients with
collateral circulation may have normal EKGs and be asymptomatic at rest but are symptomatic
with corresponding abnormal EKG findings during periods of increased cardiac demand.

Patients with a critically stenosed LAD may be asymptomatic and have normal to minimally
elevated cardiac enzymes at the time of presentation with at rest abnormal EKG findings being
the sole clue to the patient's gravity. While some studies have shown collateral coronary
circulation lead to normal EKGs, there is limited research addressing whether or not
collateral circulation affects the presence of a Wellens sign. As a result, its diagnostic
utility is questionable.

Overall Aim Coronary artery disease significantly contributes to morbidity and mortality in
the United States. Atherosclerotic disease can lead to stenosis of the coronary arteries and
subsequent cardiac hypoperfusion. Patients with a critical stenosis of the LAD, potentially
leading to acute anterior wall myocardial infarction, may be asymptomatic at presentation
with subtle EKG changes as its only manifestation. It is imperative for physicians to
recognize patients with new T wave inversions in leads V2-V3 as the standard course of
management may lead to poor prognosis.

The purpose of this study is to determine if collateral circulation to the left anterior
descending (LAD) artery will mask the presence of a Wellens sign and therefore diminish its
diagnostic utility. The conclusion of this study would raise awareness for physicians in
light of an absent Wellens sign.

Study Objectives

To identify if coronary collateral circulation masks the presence of a Wellens sign by:

Evaluating catheterization reports Examining for the presence of coronary collateral
circulation Examining EKGs for presence of deeply inverted t-waves in precordial leads
Examining EKGs for presence of biphasic t-waves in precordial leads Correlating the
presence/absence of coronary collateral circulation with EKG findings

Hypothesis:

The presence of coronary collateral circulation to the LAD masks the presence of a Wellens
sign (both Type 1 and Type 2) in precordial leads V2-V4.

Study Design This study will be a retrospective chart review of patients who received cardiac
catheterization and had LAD and/or Left Main lesions between the years 2000-2016 at Coney
Island Hospital. Catheterization imaging and reports will be reviewed for collateral
circulation. Subsequent pre-catheterization electrocardiograms, dated up to 1 year prior to
cardiac catheterization, will be reviewed for the presence or absence of symmetrical deep (≥2
mV) t-wave inversion (type 1) or biphasic t-wave (type 2) Wellens sign in precordial leads.
EKGs will be accessed either electronically or physically. All data will be de-identified and
coded to maintain patient confidentiality.

What and how will you measure or collect data to test your hypothesis (or study objectives)?
A retrospective chart review of cardiac catheterizations will be employed to assess the
presence of coronary collateral circulation. Grading of coronary collateral circulation will
be divided into four categories (0=no filling, 1=filling of side branches only, 2=partial
filling of epicardial segments, 3=complete filling of epicardial segments). In addition,
pre-catheterization EKGs will be analyzed for a.) the presence or absence of deeply inverted
t-waves (type 1) or biphasic t-waves (type 2) and b.) the amplitude (mV) of each
corresponding Wellens sign. Demographic data including medical record number, age, gender,
and known risk factors, including but not limited to diabetes, smoking, drinking, previous
myocardial infarction, hyperlipidemia, and hypertension, will be recorded for data analysis.

Describe where the research data will reside and who will have access to hold or maintain the
data? Research data will be collected and recorded on a password protected Microsoft Excel
Spreadsheet. Excel file will be saved on Coney Island Hospital servers. Computers are
password protected and every effort will be made to ensure safekeeping of the aforementioned
Excel file. File will be stored for a maximum of three years and will be permanantly
eliminated following the conclusion and publication of proposed study.

Data will be managed by Dr. Ida Hui Suen and Dr. George Juang. Data will not be released to
other collaborators. De-identified data will be forwarded to central office for assistance
with statistical analysis if needed.

Describe the methods that will be used to destroy data and/or specimens at the end of the
research study life cycle.

Efforts will be made to ensure that all files are deleted from Coney Island Servers. No
specimens will be collected.

Data Analysis Statistical analysis will be performed with the assistance of Brian Altonen of
New York Health and Hospital Corporation's Central Office. Chi Square, ANOVA, and multiple
logistic regression analyses will be applied.

Sample Size Approximately 6,000 patients received cardiac catheterizations at Coney Island
Hospital between 2003-2016. Approximately 30% will have LAD lesions (N=1800); of which
approximately 20% will have a Wellens sign (N=360).

Variables Age, Nominal Sex, Categorical (1=M, 2=F) Date of Catheterization Location of
Lesion, Categorical (1=LAD Proximal, 2=LAD Mid, 3=LAD Distal, 4=Left Main) Collaterals
present, Categorical (0=N, 1=Y) Grading of Collaterals, Categorical (0=none, 1= filling of
side branches, 2=partial filling of epicardial segment, 3=complete filling of epicardial
segment) Date of pre-cath EKG Wellens Sign Present, Categorical (1=Y, 2=N) Type of Wellens
Sign, Categorical (1=Type 1, 2=Type 2)

Inclusion Criteria:

All patients receiving cardiac catheterization between 2003-2016 at Coney Island Hospital
with LAD lesions and pre-catheterization electrocardiograms.

Exclusion Criteria: