Correlation of Echocardiographic Left Atrial Abnormality With Myocardial Ischemia During Myocardial Perfusion Assessment in Patients With Left Bundle Branch Block

Left atrial (LA) abnormality, an easily quantifiable parameter of left ventricular (LV) diastolic dysfunction, has been associated with cardiovascular risk. Because during myocardial perfusion study (MPS), the abnormal LV activation pattern in patients with left bundle branch block (LBBB) frequently induces perfusion defects, a clinical correlate of early myocardial ischemia such as LA enlargement could alleviate some of these inherent challenges. We prospectively studied 144 consecutive patients with LBBB who underwent MPS after screening for electrocardiographic and echocardiographic LA enlargement over a 6-month period. Of those, 114 had a positive MPS result. We found that LA size (p <0.0001) and P-wave duration (p = 0.001) were significantly increased in patients as the severity of the defects increased on MPS, whereas LV ejection fraction was decrementally reduced (p = 0.001). Importantly, LA size (≥43.5 mm; sensitivity 70%, specificity 89%) and P-wave duration (≥135 milliseconds; sensitivity 63%, specificity 90%) were greatest when the MPS defect was severe. In conclusion, the presence of LA enlargement appears significantly correlated with myocardial ischemia among patients with LBBB and could therefore assist during MPS interpretation among patients in whom MPS interpretation could be challenging.