Rare case of left-dominant arrhythmogenic right ventricular cardiomyopathy with dramatic reverse remodeling after cardiac resynchronization as an adjunct to pharmacological therapy

Heart Failure in Patients with Arrhythmogenic Cardiomyopathy

Arrhythmogenic cardiomyopathy (ACM) is a rare inherited cardiomyopathy characterized as fibro-fatty replacement, and a common cause for sudden cardiac death in young athletes. Development of heart failure (HF) has been an under-recognized complication of ACM for a long time. The current clinical management guidelines for HF in ACM progression have nowadays been updated. Thus, a comprehensive review for this great achievement in our understanding of HF in ACM is necessary. In this review, we aim to describe the research progress on epidemiology, clinical characteristics, risk stratification and therapeutics of HF in ACM.

A case report of arrhythmogenic ventricular cardiomyopathy presenting with sustained ventricular tachycardia arising from the right and the left ventricles before structural changes are documented

Background

Arrhythmogenic ventricular cardiomyopathy (AC) is a genetic progressive disease characterized by fibro-fatty replacement of either ventricles in isolation or in combination. Arrhythmogenic ventricular cardiomyopathy is frequently associated with ventricular tachycardia (VT) having a left bundle branch block (LBBB) morphology and much more rarely with VT having right bundle branch block (RBBB) morphology even when the left ventricle is involved. Cardiac magnetic resonance (CMR) imaging plays a key role in the diagnosis of AC. Sustained VT in AC may occur in the concealed stage of the disease before the manifestation of morphological abnormalities on echocardiogram; however, they almost always are accompanied by structural abnormalities of the ventricles on CMR.

Case summary

A 54-year-old man presented with sustained VT of LBBB configuration consistent with the diagnosis of AC but with no right ventricular (RV) anomalies at repeat CMR. Ten years later, he developed sustained VT with RBBB morphology and structural changes at CMR compatible with RV involvement in the setting of AC. Two years later, he suffered from recurrent identical sustained RBBB-VT with typical CMR signs of left ventricular involvement. Genetic analysis was negative for any known mutation.

Discussion

In the present report, we describe a patient with AC who first exhibited LBBB- and 10 years later RBBB-sustained VT. Contrasting with what is usually observed in patients with AC, documentations of the VT's arising from either ventricle were found to precede the structural anomalies in the respective cardiac chambers. This case highlights that normal CMR does not exclude underlying AC contrary to the perceptions of many clinicians. In addition, it strongly encourages repeating CMR after 1-2 years when the diagnosis of AC is highly suspected.

Response to cardiac resynchronization therapy in non-ischemic cardiomyopathy is unrelated to medical therapy

INTRODUCTION

Current guidelines recommend at least 3 months of guideline-directed medical therapy (GDMT) for patients with a new onset of non-ischemic cardiomyopathy (NICM) and left bundle branch block (LBBB) prior to cardiac resynchronization therapy (CRT). For patients who do not receive optimal GDMT, response to CRT is unknown.

METHODS

Patients with NICM and LBBB with QRS ≥ 120 ms were identified among all patients who underwent CRT. Patients who received GDMT for ≥ 3 months before CRT were compared to those who did not. Among 38 patients who met inclusion criteria, 24 received optimal GDMT prior to implantation (Group 1) and 14 did not (Group 2).

RESULTS

QRS narrowing occurred in Group 1 (160 ± 9 ms to 138 ± 20 ms, P = 0.001) and Group 2 (160 ± 17 ms to 139 ± 30 ms, P = 0.021). Left ventricular ejection fraction (LVEF) improvement occurred in Group 1 (21.3 ± 5.9% to 34.4 ± 13.9%, P < 0.001) and Group 2 (18.8 ± 4.7% to 31.1 ± 13%, P = 0.010). QRS interval and LVEF changes were similar between groups (P = NS). There was a trend towards greater CRT response in women than in men, although differences did not reach statistical significance.

CONCLUSION

In patients with NICM and LBBB, CRT is associated with improvements in LV size and function independent of prior GDMT. The ability of resynchronization to improve LVEF without GDMT suggests that CRT without waiting 3 months for GDMT optimization may benefit some patients with NICM and LBBB.

Cardiac Resynchronization Therapy in Non-Ischemic Cardiomyopathy

Cardiac resynchronization therapy (CRT) is an established therapy for heart failure patients who remain symptomatic despite optimal medical therapy, have reduced left ventricular ejection fraction (<35%) and wide QRS duration (>120 ms), preferably with left bundle branch block morphology. The response to CRT depends on the cardiac substrate: presence of correctable left ventricular mechanical dyssynchrony, presence of myocardial fibrosis (scar) and position of the left ventricular pacing lead. Patients with non-ischemic cardiomyopathy have shown higher response rates to CRT compared with patients with ischemic cardiomyopathy. Differences in myocardial substrate may partly explain this disparity. Multimodality imaging plays an important role to assess the cardiac substrate and the pathophysiological determinants of response to CRT.

Arrhythmogenic substrate at the interventricular septum as a target site for radiofrequency catheter ablation of recurrent ventricular tachycardia in left dominant arrhythmogenic cardiomyopathy

Background

Left dominant arrhythmogenic cardiomyopathy (LDAC) is a rare condition characterised by progressive fibrofatty replacement of the myocardium of the left ventricle (LV) in combination with ventricular arrhythmias of LV origin.

Case presentation

A thirty-five-year-old male was referred for evaluation of recurrent sustained monomorphic ventricular tachycardia (VT) of 200 bpm and right bundle branch block (RBBB) morphology. Cardiac magnetic resonance imaging showed late gadolinium enhancement distributed circumferentially in the epicardial layer of the LV free wall myocardium including the rightward portion of the interventricular septum (IVS). The clinical RBBB VT was reproduced during the EP study. Ablation at an LV septum site with absence of abnormal electrograms and a suboptimum pacemap rendered the VT of clinical morphology noninducible. Three other VTs, all of left bundle branch block (LBBB) pattern, were induced by programmed electrical stimulation. The regions corresponding to abnormal electrograms were identified and ablated at the mid-to-apical RV septum and the anteroseptal portion of the right ventricular outflow tract. No abnormalities were found at the RV free wall including the inferolateral peritricuspid annulus region. Histological examination confirmed the presence of abnormal fibrous and adipose tissue with myocyte reduction in endomyocardial samples taken from both the left and right aspects of the IVS.

Conclusion

LDAC rarely manifests with sustained monomorphic ventricular tachycardia. In this case, several VTs of both RBBB and LBBB morphology were amenable to endocardial radiofrequency catheter ablation.