48 A CASE OF RECURRENT VENTRICULAR TACHYCARDIA IN A PATIENT WITH GRANULOMATOSIS WITH POLYANGIITIS WITH A CHALLEGING IDENTIFICATION OF ARRHYTHMIC SUBSTRATE: THE ROLE OF MULTIMODALITY IMAGING


 
 
 Granulomatosis with polyangiitis (GPA), previously known as Wegener's granulomatosis, is a pulmonary-renal syndrome affecting small and medium sized blood vessels. Cardiac involvement is rare and generally includes pericarditis, myocarditis and aortic valve disease. We report a case of recurrent sustained ventricular tachycardia (VTs) in a patient with GPA.
 
 
 
 A 67-year-old man with past medical history of GPA presented palpitations, chest pain and episodes of presyncope. Electrocardiographic tracing upon ED presentation showed sustained monomorphic VT (fig.1) associated with global hypokinesia of the left ventricle and moderately reduced ejection fraction at transthoracic echocardiography (TTE). As the patient was hemodynamically stable, prompt treatment with amiodarone was adopted with successful recovery of sinus rhythm. After a few hours, TTE was normal. However, as troponin I was markedly elevated, coronarography was performed and coronary disease was ruled out. Contrast-enhanced cardiac magnetic resonance imaging (ceCMR) revealed late gadolinium enhancement in basal anteroseptal mid wall, suggestive of myocardial scar tissue with non-ischemic pattern. No sustained ventricular arrhythmias were induced during electrophysiological study (EPS), even with an aggressive protocol (up to 4 extra stimuli and ventricular refractoriness) and electro-anatomical mapping of both ventricles failed to show any arrhythmic substrate. An implantable cardioverter defibrillator (ICD) was then implanted. After 4 months the patient was admitted for multiple episodes of sustained VT (with cycle length in the ICD monitoring window) refractory to drugs and three external defibrillations. Repeated EPS failed to induce sustained arrhythmias. High-density electroanatomical mapping of the right ventricle, however, showed fragmented potentials in the mid-posterior septal wall (fig. 2-3). After myocardial biopsy of the region of interest, radiofrequency catheter ablation of the area was performed with regression of the potentials. The results of endomyocardial biopsy demonstrated fibrosis. At 5 months of follow-up, the patient didn't relapse.
 
 
 
 Multimodality imaging is of paramount importance in identifying arrhythmogenic substrate and in characterizing the specific anatomical–functional components of VT circuits. In our patient high-density electroanatomical mapping was able to identify fragmented potentials and define the ablation target area, despite the mismatch with ceCMR.
