Background: In patients with left bundle branch block (LBBB), conventional tests such as electrocardiography and myocardial scintigraphy poorly evaluate coronary artery disease. It has been reported that myocardial contrast echocardiography (MCE) is capable of identifying patients with a postinfarction contractile reserve and myocardial functional recovery, also allowing the early identification of late left ventricular remodeling. The purpose of this study was to evaluate, retrospectively, myocardial perfusion in selected patients with LBBB.
Methods: Thirty patients (mean age 56 +/- 8 years) with LBBB, 15 with normal coronary arteries at angiography and 15 with a previous myocardial infarction and a critical one-vessel residual stenosis at angiography, underwent MCE from June 2000 to May 2001. MCE results were compared with rest thallium-201 myocardial scintigraphy.
Results: Among 15 LBBB patients with normal coronary arteries, MCE demonstrated normal perfusion in 14 patients, whereas 1 subject showed an impairment of septal perfusion. In the same group, rest thallium-201 myocardial scintigraphy showed an impaired septal perfusion in 14 patients, whereas 1 subject had a normal perfusion (MCE specificity 93% vs myocardial scintigraphy specificity 7%). Among 15 LBBB patients with coronary artery disease, MCE correctly identified a contrast defect in 14/15 patients, whereas rest thallium-201 myocardial scintigraphy demonstrated a perfusion defect in 15/15 patients (MCE sensitivity 93% vs scintigraphy sensitivity 100%). The two techniques showed a good agreement as for myocardial perfusion in the anterior wall (86.6% anterobasal; 86.6% mid-anterior; 80% distal anterior), the inferior wall (86.6%), the distal segment of the posterior lateral wall (83.3%), but a low concordance was found as for the basal septum (16.6%) and middistal septum (33.3%).
Conclusions: MCE allows a diagnostic benefit in the detection of microvascular damage in patients with LBBB and unknown coronary artery disease, also in the presence of discordance with rest thallium-201 myocardial scintigraphy.