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Detecting exercise-induced ischemia in left bundle branch block using the electrocardiogram
N S Ibrahim1, G Abboud, R S Selvester
1Memorial Heart Institute, Long Beach, California 90801, USA.
Insights
Electrocardiographic changes during exercise can identify coronary artery obstruction in patients with left bundle branch block. Specifically, ST depression in leads II and AVF and increased R-wave amplitude in lead II are significant indicators of ischemia.
Area of Science:
- Cardiology
- Diagnostic Imaging
Background:
- Left bundle branch block (LBBB) can complicate exercise electrocardiography interpretation.
- Accurate diagnosis of coronary artery disease (CAD) in LBBB patients is clinically important.
Purpose of the Study:
- To identify specific 12-lead electrocardiographic (ECG) changes during exercise that reliably indicate significant coronary artery obstruction in patients with LBBB.
Main Methods:
- Compared exercise ECG findings in 41 patients with LBBB.
- Patients were categorized into nonischemic (n=7) and those with significant coronary artery obstruction (>=70% by angiogram, n=34).
- Analyzed ST depression at the J point and R-wave amplitude changes in specific leads.
Main Results:
- ST depression of >=0.5 mm from baseline at the J point in leads II and AVF significantly identified ischemia (p=0.004).
- An increase in R-wave amplitude in lead II also significantly correlated with ischemia (p=0.05).
Conclusions:
- Exercise-induced ST depression in leads II and AVF and increased R-wave amplitude in lead II are valuable indicators of significant coronary artery obstruction in patients with LBBB.
- These ECG findings can aid in diagnosing ischemia in this challenging patient population.
Abstract:
We compared 12-lead electrocardiographic changes during exercise in 41 patients with left bundle branch block; 7 were nonischemic and 34 had coronary artery obstruction > or =70% as detected by angiogram. ST depression of > or =0.5 mm from baseline when measured at the J point in leads II and AVF (p=0.004) and an increase of R-wave amplitude in lead II (p=0.05) significantly identified ischemia.