Myocardial blood flow assessment with 82rubidium-PET imaging in patients with left bundle branch block

• Main Authors: Andréa Falcão, William Chalela, Maria Clementina Giorgi, Rodrigo Imada, José Soares Jr, Renata Do Val, Marco Antonio Oliveira, Marisa Izaki, Roberto Kalil Kalil Filho, José C. Meneghetti
• Format: Article
• Language: English
• Published: Faculdade de Medicina / USP 2015-11-01
• Series: Clinics
• Subjects: Myocardial Blood Flow; Left Bundle Branch Block; Positron Emission Tomography (PET); Myocardial Perfusion Imaging; Coronary Flow Reserve
• Online Access: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1807-59322015001100726&lng=en&tlng=en

OBJECTIVES: Perfusion abnormalities are frequently seen in Single Photon Emission Computed Tomography (SPECT) when a left bundle branch block is present. A few studies have shown decreased coronary flow reserve in the left anterior descending territory, regardless of the presence of coronary artery disease. OBJECTIVE: We sought to investigate rubidium-82 (82Rb) positron emission tomography imaging in the assessment of myocardial blood flow and coronary flow reserve in patients with left bundle branch block. METHODS: Thirty-eight patients with left bundle branch block (GI), median age 63.5 years, 22 (58%) female, 12 with coronary artery disease (≥70%; GI-A) and 26 with no evidence of significant coronary artery disease (GI-B), underwent rest-dipyridamole stress 82Rb-positron emission tomography with absolute quantitative flow measurements using Cedars-Sinai software (mL/min/g). The relative myocardial perfusion and left ventricular ejection fraction were assessed in 17 segments. These parameters were compared with those obtained from 30 patients with normal 82Rb-positron emission tomography studies and without left bundle branch block (GII). RESULTS: Stress myocardial blood flow and coronary flow reserve were significantly lower in GI than in GII (p<0.05). The comparison of coronary flow reserve between GI-A and GI-B showed that it was different from the global coronary flow reserve (p<0.05) and the stress flow was significantly lower in the anterior than in the septal wall for both groups. Perfusion abnormalities were more prevalent in GI-A (p=0.06) and the left ventricular ejection fraction was not different between GI-A and GI-B, whereas it was lower in GI than in GII (p<0.001). CONCLUSION: The data confirm that patients with left bundle branch block had decreased myocardial blood flow and coronary flow reserve and coronary flow reserve assessed by 82Rb-positron emission tomography imaging may be useful in identifying coronary artery disease in patients with left bundle branch block.