Solitary Fatty Infiltration Within the Left Ventricle Detected by Cardiac Magnetic Resonance Imaging in a Patient Presenting With Ventricular Tachycardia
A 58-year-old black woman with a past medical history of recurrent presyncope, hypertension, depression, and breast cancer with right lumpectomy was admitted with symptoms of palpitations, chest pressure accompanied by numbness, and exertional dyspnea. An admission resting ECG revealed sinus rhythm without evidence of a prior myocardial infarction associated with occasional premature ventricular beats. A telemetry surveillance rhythm strip demonstrated nonsustained ventricular tachycardia with a left bundle block pattern (Figure 1). Transthoracic echocardiography examination was performed that showed normal biventricular morphology, size, and systolic function with no regional wall motion abnormalities (Movie I in the online-only Data Supplement). To further investigate the cause of the nonsustained ventricular tachycardia and to exclude any possible structural heart disease, a cardiac magnetic resonance (CMR) study with gadolinium contrast was performed. The CMR confirmed the normal biventricular size and systolic function (Movie II in the online-only Data Supplement) and, interestingly, revealed a region of intramyocardial fatty infiltration in the inferoseptal and septal walls of the left ventricle (LV) (Figure 2). The employed CMR protocol, which included cine steady state free precession images, resting first pass perfusion after gadolinium injection, late gadolinium enhancement images (LGE), and specific sequences to identify fat (T1-weighted turbo spin echo with and without fat suppression), provided clear identification of a layer of fatty infiltration in the inferoseptal and septal walls of the LV (Figure 3) and a matching resting first-pass perfusion defect (Figure 4A) without any evidence of scar documented by normal LGE images (Figure 4B). Among the various CMR techniques employed, only the T1-weighted turbo spin echo with and without fat suppression represents definitive evidence of fatty infiltration. LGE image sequences are not sufficient to definitively demonstrate fatty infiltration because fat suppression techniques are rarely used with LGE. Furthermore, gadolinium injection inherently changes the tissue T1 and T2 parameters, further reducing the ability to identify relatively small regions of fatty infiltration. Sequences other than the T1-weighted spin echo with and without fat saturation are in agreement with this finding; however, the abnormal intraventricular signal could be due to other changes in the tissue. Moreover, the CMR did not reveal any morphological abnormalities within the right ventricle. Subsequently, the patient underwent an invasive electrophysiology study revealing first-degree atrioventricular block with mild conduction delay in the His-Purkinje system (HV interval 80 ms). Programmed right ventricular (RV) stimulation reproducibly induced polymorphic ventricular tachycardia with double extrastimulation requiring external defibrillation for conversion to sinus rhythm. An implantable cardioverter-defibrillator was subsequently implanted, and during the same procedure, 3 different RV (apical, outflow, and anterior wall) tissue samples were obtained. The tissue samples did not show evidence of fatty infiltration or any other infiltrative disease, which also supports the CMR findings that revealed no abnormality within the RV.
Although several cases of arrhythmogenic RV cardiomyopathy with LV involvement have been reported, it often occurs in the later stage of the spectrum of the disease1–3 and usually does not present as an isolated phenomenon independent of RV involvement.4 More recently, Sen-Chowdhry et al5 defined the clinical and genetic profile of left-dominant arrhythmogenic cardiomyopathy, showing that >50% of the clinical left-dominant arrhythmogenic cardiomyopathy cohort had septal abnormalities detected by CMR, and >30% had LV dilation or impairment in the presence of preserved right-sided volumes and function.
Guest Editor for this article was Francis J. Klocke, MD.
The online-only Data Supplement is available with this article at http://circ.ahajournals.org/cgi/content/full/CIRCULATIONAHA.108.839142/DC1.
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