Clinical Trial: Left Bundle Branch Block ECG Characteristics in the Evaluation of Acute Coronary Syndrome

Study Status: Terminated
Recruit Status: Terminated
Study Type: Observational

Official Title: Correlation of Clinical Outcomes With ECG Findings in Patients With Left Bundle Branch Block Being Evaluated for Acute Coronary Syndrome - a Prospective Cohort Study

Brief Summary:

Purpose of the study:

The goal of this study is to evaluate the relationship of electrocardiogram (ECG) findings with clinical outcomes in a cohort of patients with left bundle branch block (LBBB) who are being evaluated for acute coronary syndrome (ACS) in the Emergency Department (ED).

Background and significance:

The significance of specific ECG findings in patients with LBBB being evaluated for ACS has been inadequately studied, and this gap in knowledge is a barrier to optimal management of this population. Due to the speed, availability, low cost, and non-invasive nature of the ECG, it would be ideal to identify ECG characteristics that help to risk stratify these patients in order to inform clinical decision-making, reduce unnecessary invasive testing, and conserve resources.

Methods:

In this prospective observational study the investigators will identify a consecutive series of adult patients with LBBB presenting to the ED with suspicion of ACS. The investigators will collect data including demographics, cardiac risk factors, initial ECG measurements, lab and radiographic results, procedure results, and clinical outcomes such as 30-day death or myocardial infarction (MI). The investigators will analyze the data using a cohort study design to calculate odds ratios between ECG characteristics and the outcomes of interest.


Detailed Summary:

Purpose of the study:

The goal of this study is to identify initial electrocardiogram (ECG) findings (including ST/S ratio and T-wave morphology) that predict clinical outcomes (myocardial infarction, positive stress test, revascularization and death), in a cohort of Emergency Department (ED) patients with left bundle branch block (LBBB) who are being evaluated for acute coronary syndrome (ACS).

Design & procedures:

The investigators will prospectively identify all adult (18yrs and older) patients presenting to their institution's ED who are being evaluated for ACS and have LBBB on ECG. The investigators will collect data on demographics (including age, but not date of birth), cardiac risk factors, date and time of presentation to the ED, ECG measurements, lab and radiographic results (cardiac biomarker data including date and time of the sample, stress test results, coronary imaging results, coronary catheterization results) and clinical outcomes such as 30-day death or MI. They will collect copies of ECGs and measure the following: ST/S ratio (ratio of the amplitude of ST segment deviation to the S wave amplitude); T-wave morphology (entirely discordant, entirely concordant, or biphasic to the PR interval); and standard ST segment deviation. A logistic regression analysis will be used to identify which ECG features are associated with 30-day death, MI, and revascularization. In the sub-cohort of subjects with negative "modified Sgarbossa criteria" a subanalysis will identify the outcome rates for the following specific sub-populations: those less than 2 consecutive partially-concordant T-wave leads and those with 2 or more consecutive partially-concordant T-wave leads.

Selection of Subjects:

  • Sensitivity of non-discordant T waves for prediction of positive cardiac biomarkers on index visit [ Time Frame: The ECG will be the ECG on presentation to the ED. The maximum cardiac troponin within 48 hours of index visit will be used as the outcome. ]

    Diagnostic properties (sensitivity, specificity, likelihood ratios) of item 1 for item 2 below:

    1. Presence of at least two ECG leads with non-discordant T waves (meaning either entirely concordant or biphasic, relative to the PR interval)
    2. Positive (above the assay's normal reference range) cardiac biomarkers (cardiac troponin I, T, or CK-MB) within 48 hours of presentation to the ED.
  • Specificity of non-discordant T waves for prediction of positive cardiac biomarkers on index visit [ Time Frame: The ECG will be the ECG on presentation to the ED. The maximum cardiac troponin within 48 hours of index visit will be used as the outcome. ]

    Diagnostic properties (sensitivity, specificity, likelihood ratios) of item 1 for item 2 below:

    1. Presence of at least two ECG leads with non-discordant T waves (meaning either entirely concordant or biphasic, relative to the PR interval)
    2. Positive (above the assay's normal reference range) cardiac biomarkers (cardiac troponin I, T, or CK-MB) within 48 hours of presentation to the ED.
  • Positive likelihood ratio of non-discordant T waves for prediction of positive c

    Original Primary Outcome: Same as current

    Current Secondary Outcome:

    • Sensitivity of various exploratory ECG findings for positive cardiac biomarkers [ Time Frame: The ECG measurements at presentation to the ED will be used, to predict maximum cardiac troponin within 48 hours of presentation to the ED. ]
      Logistic regression will be used to test multiple ECG measurements (other than the primary outcome, listed above) for diagnostic utility to predict positive cardiac biomarkers. Potentially relevant ECG findings will be explored via an ROC curve to find optimal cutpoints for diagnostic accuracy, and presented by means of diagnostic properties including sensitivity, specificity, and likelihood ratios. These findings will be explicitly listed as post-hoc, exploratory findings meant only to direct further research.
    • Specificity of various exploratory ECG findings for positive cardiac biomarkers [ Time Frame: The ECG measurements at presentation to the ED will be used, to predict maximum cardiac troponin within 48 hours of presentation to the ED. ]
      Logistic regression will be used to test multiple ECG measurements (other than the primary outcome, listed above) for diagnostic utility to predict positive cardiac biomarkers. Potentially relevant ECG findings will be explored via an ROC curve to find optimal cutpoints for diagnostic accuracy, and presented by means of diagnostic properties including sensitivity, specificity, and likelihood ratios. These findings will be explicitly listed as post-hoc, exploratory findings meant only to direct further research.
    • Positive likelihood ratio of various exploratory ECG findings for positive cardiac biomarkers [ Time Frame: The ECG measurements at presentation to the ED will be used, to predict maximum cardiac troponin within 48 hours of presentation to the ED. ]
      Logistic regression will be used to test multiple ECG measurements (other than the primary outcome, listed above) for diagnostic utility to predict positive cardiac biomarkers. Potentially relevant ECG findings will be explored via an ROC curve to find optimal cutpoints for diagnostic accuracy, and presented by means of diagnostic properties including sensitivity, specificity, and likelihood ratios. These findings will be explicitly listed as post-hoc, exploratory findings meant only to direct further research.
    • Negative likelihood ratio of various exploratory ECG findings for positive cardiac biomarkers [ Time Frame: The ECG measurements at presentation to the ED will be used, to predict maximum cardiac troponin within 48 hours of presentation to the ED. ]
      Logistic regression will be used to test multiple ECG measurements (other than the primary outcome, listed above) for diagnostic utility to predict positive cardiac biomarkers. Potentially relevant ECG findings will be explored via an ROC curve to find optimal cutpoints for diagnostic accuracy, and presented by means of diagnostic properties including sensitivity, specificity, and likelihood ratios. These findings will be explicitly listed as post-hoc, exploratory findings meant only to direct further research.


    Original Secondary Outcome: Same as current

    Information By: Duke University

    Dates:
    Date Received: October 31, 2014
    Date Started: November 2014
    Date Completion:
    Last Updated: September 24, 2015
    Last Verified: August 2015