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Unusual cause of ventricular tachycardia with left-bundle branch block pattern

Here we report the case of a 47 year-old man who presented at emergency unit with a ventricular tachycardia (VT) with left-bundle branch block (LBBB) pattern and inferior axis suggesting VT coming from the right ventricular outflow tract (RVOT) (figure 1). The ECG showed T-wave inversion in all precordial leads. It also displayed polymorphic ventricular ectopies (Vec) with RBBB and LBBB pattern (figure 1) and 1st degree AV block.
The morphological analysis (echocardiography and angiography) showed an abnormal RV with excessive trabeculations, anterior akinesia, apical dyskinesia, mild RV dilatation associated with a moderately dilated left ventricle (LV) with mild LV global hypokinesia (LV ejection fraction 44%). The signal-average ECG displayed late potentials.

Question 1. What are your diagnosis?

Interestingly, the repolarization abnormalities were changing and became more prominent in the left lateral precordial leads during follow-up (figure 1). The conduction abnormalities worsened, as a complete RBBB associated with a left fascicular anterior block associated with permanent long AV block appeared four years later. Non-sustained VT (NSVT) persisted despite anti-arrhythmic therapy and an ablation was attempted that revealed five different VTs coming from both ventricles including one of epicardial origin. An ICD was then implanted. The patient secondarily developed persistent atrial fibrillation that needed cardioversion.

Figure 1 : Top : Electrocardiograms of the proband between 2007 and 2011. At the time of diagnosis (2007), T-wave inversion was present in all precordial leads but later was only present in left lateral leads. Please notice the three different morphologies of ventricular ectopies : A with RBBB pattern and right axis suggestive of lateral LV origin, B : narrow QRS with normal axis and V1-V2 transition suggestive of septal origin, C: LBBB with inferior axis suggestive of RVOT origin; D : same morphology as A but with wider QRS suggestive of epicardial origin. * : note the worsening of conduction disease with apparition of complete RBBB with left axis and long AV block. Bottom : clinical VT with LBBB and inferior axis suggesting VT from RVOT.

Question 2. What are your etiological hypotheses?

Question 3. Which additional diagnostic work-up do you suggest?

The familial history revealed that the mother suddenly died aged 80 (figure 2). The maternal uncle was implanted with a pace-maker but died suddenly aged 80. Two maternal aunts displayed heart failure and suddenly died aged 60. The maternal grandfather suddenly died aged 51. The sister experienced several episodes of syncope from age 50 and was implanted with a pace-maker aged 67 due to high-degree AV block. She further developed paroxysmal atrial fibrillation and ventricular arrhythmias with NSVT. The echocardiography was normal. The 28 yo daughter had a normal echocardiography but displayed atrial ectopies and NSVT.

Figure 2 : Pedigree of the family. The arrow indicates the proband. Squares indicate male and circles female. Affected individuals are shown with solid symbols, unaffected with white symbols and possibly affected in grey. ICD: implantable cardiac defibrillator; HF: heart failure; VT: ventricular tachycardia; NSVT: non-sustained VT; AF: atrial fibrillation; AEc: atrial ectopies; PM: pace-maker; SD: sudden death

Question 4. Which genetic disease you suspect?  

Notes to editor

Estelle Gandjbakhch, Pascale Richard, Philippe Charron.
"Centre de référence pour les Maladies cardiaques héréditaires", Hôpital Pitié-Salpêtrière & Université Paris 6, Paris, France.
The content of this article reflects the personal opinion of the author/s and is not necessarily the official position of the European Society of Cardiology.