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

Luciano De Biase 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 cardiogical 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 high temporal resolution 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 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%).

Cardiac MRI is a useful diagnostic tool in the evaluation of LBBB, in patients where the assessment of ventricular dyssynerygy on echocardiography is not technically possible and when the area of previous myocardial infarction cannot be determined.

MRI is useful in the evaluation of LBBB allowing diagnosis of possible underlying CAD with the detection of the location and the extension (subendocardial vs transmural) of myocardial infarction.

Di Girolamo, M, De Cecco, C, Muscogiuri, G, Fierro, S, De Biase, L, David, V, Left Bundle Branch Block: Usefulness of MRI in the Evaluation of Regional Left Ventricular Dyssynchrony and in the Detection of Previous Myocardial Infarction with Late Enhancement.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11034416.html