Marco Di Girolamo MD, Presenter: Nothing to Disclose

Carlo Nicola De Cecco MD, Abstract Co-Author: Nothing to Disclose

Giuseppe Muscogiuri, Abstract Co-Author: Nothing to Disclose

Stefano Fierro, Abstract Co-Author: Nothing to Disclose

Michelangelo Maurizi Enrici MD, Abstract Co-Author: Nothing to Disclose

Vincenzo David MD, Abstract Co-Author: Nothing to Disclose

Left bundle branch block (LBBB) is a common cardiac conduction abnormality diagnosed on ECG. LBBB can be a primary abnormality of the cardiac electrical conduction system or it can be secondary to other cardiac pathologies such as myocardial infarction and cardiomyopathies. The presence of LBBB per se cannot be used as a single diagnostic criteria for the diagnosis of previous myocardial infarction. Aim of this study was to evaluate the mechanical left ventricular dyssynchrony with cine MRI and to evaluate the presence of late-enhancement (LE) in order to diagnose previous myocardial infarction.

38 patient with LBBB underwent cardiac MRI using a 1.5 T magnet (Magnetom Sonata, Siemens). The MRI protocol consisted of a left ventricular trueFISP functional study followed by Late Enhancement data sets acquired 10-15 minutes after iv administration of 0.2mmol/kg BW of extracellular Gd contrast agent. We used a segmented Inversion Recovery Turbo-FLASH sequence (TR:8ms;TE:4ms;TI:250-320ms;sl.thick:8mm). Different pattern of LE were related to the underlying pathology as stated by clinical and other diagnostic imaging features.

We detected a characteristic dyssynchronous ventricular contraction with septal flattening during early ventricular systole in all the patients, tenting of the mitral valve apparatus in 5 pts and functional mitral regurgitation in 2 pts. In 1 pt we found the characteristic functional features of dilated cardiomyopathy with no myocardial area of LE. In 8 pts we found areas of LE (transmural in 3 pts and subendocardial in 5 pts) with typical patterns of myocardial infarction (MI). The location of MI was septal in 4 pts, infero-septal in 2 pts, lateral in 1pt, and superior in 1 pt. In 30 patients we found a reduction of the ejection fraction (75%).

In our limited experience LBBB was a primary abnormality of the cardiac conduction system in 29 pts and secondary to other myocardial pathologies in 9 pts. Cardiac MRI is a useful diagnostic tool in the evaluation of LBBB, in patients where the assessment of ventricular dyssynergy on echocardiography is not technically possible and when the area of previous myocardial infarction cannot be determined.   

MRI is a useful diagnostic tool in LBBB when the assessment of ventricular dyssynergy on US is not technically possible and when the area of previous myocardial infarction cannot be determined.

Di Girolamo, M, De Cecco, C, Muscogiuri, G, Fierro, S, Maurizi Enrici, M, David, V, Left Bundle Branch Block: Usefulness of MR Imaging in the Evaluation of Regional Left Ventricular Dyssynchrony and in the Detection of Previous Myocardial Infarction with Late Enhancement.  Radiological Society of North America 2010 Scientific Assembly and Annual Meeting, November 28 - December 3, 2010 ,Chicago IL. http://archive.rsna.org/2010/9009848.html