Arrhythmogenic Cardiomyopathy with Biventricular Involvement and Right Ventricular Thrombosis: A Multi-modality Imaging Approach

Abstract

Arrhythmogenic cardiomyopathy (AC) is an inherited heart disease characterized by fibro-fatty changes of either ventricles in isolation or in combination. AC may present with ventricular tachycardia (VT), usually with a left bundle branch block (LBBB) morphology (although VT with right bundle branch block morphology may also be encountered). Diagnosis is multi-parametric and cardiovascular magnetic resonance (CMR) holds a key role in showing the typical tissue abnormalities of the ventricles. We report the case of a patient presenting with LBBB VT with multi-modality imaging findings consistent with AC with biventricular involvement and right ventricular (RV) thrombosis. The patient was treated with antiarrhythmics, heart failure therapy, and implantable cardioverter-defibrillator implantation. RV thrombus was treated with new oral anticoagulants.

INTRODUCTION

Arrhythmogenic cardiomyopathy (AC) is a genetic disease characterized by myocardial fibro-fatty replacement that may involve both ventricles[1,2] and may lead to ventricular arrhythmias and sudden cardiac death, sometimes as presenting symptoms. Because of the diagnostic complexity of the disease and the specific myocardial tissue changes, CMR is a key component to the diagnosis of AC.[3] In 2020, an international expert consensus provided upgraded diagnostic criteria for AC (the “Padua Criteria”).[4]

We present the case of a patient with biventricular AC and right ventricular (RV) thrombosis to discuss the challenges that may be related to this complication.

CASE PRESENTATION

A 35-year-old Bahraini male presented to the Emergency Department at Mohammed bin Khalifa Cardiac Center for a sudden-onset, generalized numbness involving the face and extremities. This was followed by chest heaviness, shortness of breath (SOB), palpitations, and mild sweating. His symptoms, occurring at rest, lasted for an hour. The patient reported an episode of sudden onset of dizziness while playing football 2 days before his presentation. Furthermore, he also mentioned recurrent chest pain on exertion associated with SOB for few months.

The patient denied any history of chronic medical illness and was not taking any regular medications. However, he was a chronic active smoker and had a strong family history of coronary artery disease as both his brothers had undergone coronary angioplasty in their 40s. On physical examination, no remarkable findings were noted. Blood investigations revealed a significant elevation of troponin (HS) – 2.5 ug/L (normal value: 0–0.02 ug/L), CK – 306 IU/L (normal value: 20–200 IU/L), and a mildly increased D-dimer of 0.56 µg/ml (normal value: 0–0.5 µg/ml). Lipid profile showed newly detected dyslipidemia with LDL of 4.7 (normal value: 0–2.59 mmol/L). Renal and liver function tests were within normal ranges.

The electrocardiogram (ECG) showed hemodynamically stable monomorphic ventricular tachycardia (VT) with left bundle branch block morphology with inferior axis [Figure 1]. He was treated with electrical cardioversion, with the restoration of sinus rhythm, and was subsequently given intravenous amiodarone infusion for 24 h.

Figure 1.

Admission electrocardiogram showing left bundle branch block/inferior axis ventricular tachycardia

His subsequent ECG showed sinus rhythm with T-waves inversion in anterolateral leads [Figure 2]. He was admitted with the diagnosis of VT.

Figure 2.

Electrocardiogram after electrical cardioversion showing sinus rhythm with anterolateral T-wave inversion

Transthoracic echocardiogram showed moderately reduced LV ejection fraction (35–40%) with diffuse hypokinesis. The proximal and distal RV outflow tract (RVOT) was dilated with reduced RV function (ejection fraction 39%). A large heterogenous, partially mobile mass was seen in the mid RV cavity, attached to the trabeculae measuring 1.1 cm × 0.84 cm appearing as a filling defect on contrast-enhanced echo images suggestive of thrombus [Figure 3].

Figure 3.

Transthoracic echo without contrast (a) and with Optison intravenous contrast (b) showing right ventricular thrombus (yellow arrows)

His Computed topography coronary angiogram (CTCA) [Figure 4] confirmed the presence of a thrombus described as multilobular mass with serpiginous elements, attached to the RV side of the septum measuring approximately 1.6 cm × 0.97 cm [Figure 5]. The patient’s coronary arteries only showed mild atheroma in the left anterior descending artery.

Figure 4.

Cardiac computed tomography showing right ventricle thrombus attached to right ventricular side of septum measuring approximately 1.65 cm × 0.9 cm, multilobular with serpiginous elements. No contrast enhancement. No calcifications (a-c, yellow arrows)

Figure 5.

Diastolic (top panel) and systolic (bottom panel) four-chamber (a and d), three chambers (b and d) and right ventricular two-chamber (c and f) cine sequences. Focal dyskinesia of the basal right ventricular free wall is noted in the systolic four-chamber cine view (d, white arrow). Thinning of the mid-apical posterolateral left ventricular wall due to fat infiltration is noted in the systolic three-chamber cine view (e, white asterisk). Dilated right ventricular outflow tract is noted in the right ventricular two-chamber cine (c, yellow arrows)

A cardiac MRI was performed and showed findings consistent with AC with biventricular involvement. The right ventricle was dilated with regional wall motion abnormalities, and there was LV wall thinning in areas of epicardial fat infiltration [Figures 5 and 6]. Other findings were dilated RVOT, impaired right ventricle (RV) function with an ejection fraction of 35%, increased RV end-diastolic volume of 207.90 ml (BSA normalized value: 112.50 ml/m²), increased end-systolic volume of 135.70 ml (BSA normalized value: 73.43 ml/m²), and impaired RV end-diastolic volume index of >110 mls/msq.

Figure 6.

Myocardial tissue characterization by cardiovascular magnetic resonance: Fat infiltration. Axial T1-weighted image (a) showing mid-wall fat infiltration of the interventricular septum (a, white arrows); fat infiltration appears as a bright signal (a, white arrows) on the T1-weighted image and as a hypointense signal (b, red arrows) on the corresponding axial T1-weighted fat-sat image (b, red arrows). Fat infiltration appears as a hypointense signal on T2-weighted fat-sat images (c, yellow arrows)

Extensive LV nonischemic late gadolinium enhancement (LGE) was noted, along with LGE of the right ventricle; the RV thrombosis was also confirmed [Figure 7]. In addition, T1 isnormal in the base to mid septum and the area of prolonged T1 on the RV side of the apical septum is consistent with fibrosis and corresponds to LGE.

Figure 7.

Long (top panel) and short axis (bottom panel) cardiovascular magnetic resonance postcontrast images. An epicardial late gadolinium enhancement (LGE) stria is noted in the left ventricular into right ventricular entricular septum (a, white arrow) and basal posterolateral wall (b, white arrow). A thrombus is note in the mid-cavity right ventricle (a and c, yellow arrow). An epicardial LGE stria is noted in the basal lateral wall (d, white arrowheads). Focally transmural LGE is noted in the mid-cavity right ventricular inferior wall (e, red arrowheads) along with the thrombus (e, yellow head). A mid-wall/epicardial LGEc stria is also noted in the apical septum (f: white arrows)

The left ventricle (LV) was mildly dilated with an LV end-diastolic volume index of 111 mls/msq (normal <100). LV ejection fraction was reduced at 35%.

The patient was started on NOAC (rivaroxaban) for the management of RV clot along with maximized anti-heart failure medications, including bisoprolol, valsartan, spironolactone, empagliflozin, and amiodarone. Subsequently, a single-chamber implantable cardioverter-defibrillator (ICD) was implanted successfully for secondary prevention. The patient had an uncomplicated hospital stay and was discharged on day 6.

Follow-up visit and echo

On follow-up, the repeated echocardiogram showed severe biventricular dysfunction without evidence of ventricular thrombosis. No further arrhythmias were detected on ICD interrogation.

DISCUSSION

This case demonstrates the rare finding of RV thrombosis in a patient with AC with biventricular involvement. As per the 2020 Padua criteria, this patient met the AC criteria. Diagnosis of AC has evolved from the 1994 and 2010 criteria, by including the entities of LV predominant and biventricular AC and specific CMR tissue characterization features.[5]

AC is a rare inherited cardiomyopathy, and the reported incidence varies from 1:1000 to 1:1250 in some studies to 1:1000 to 1:5000 in others.[6]

RV thrombus is a rare complication but has been described in the setting of severe RV systolic dysfunction and dilatation. Akdis D studied 13 patients with ARVD complicated with an RV thrombus, all having severely impaired RV function (RV fractional area change: 16 ± 9% and RV ejection fraction: 15 ± 4%).[7] Chengjun Xia described the case of a patient with ARVD with severe RV systolic dysfunction (RV ejection fraction 10%) and a thrombus located in the RV apex.[8]

An echocardiogram remains a sensitive modality to diagnose RV thrombus, which can improve with the contrast agent. Yet other modalities, such as cardiac computed tomography and CMR, can be used to increase diagnostic accuracy.

Our patient had moderately reduced RV function (RV fractional area change by echocardiography 39% and RV ejection fraction by CMR 35%). The thrombus was located distal to the moderator band and attached to the septum. This strengthens the importance of carefully looking for RV thrombosis, even in cases of mild RV systolic dysfunction.

The incidence of RV thrombosis in the setting of AC is not clearly established. However, its detection has increased since the use of multi-modality imaging. This should encourage clinicians and sonographers to look carefully for thrombi in the setting of AC.

Rivaroxaban as the anticoagulant agent of choice was used in two reported cases[8,9] with successful resolution of thrombus. Our patient was also efficaciously treated with rivaroxaban 20 mg daily.

CONCLUSION

AC is a rare disease that requires a correct diagnosis to prompt timely management; as diagnosis of AC is multi-parametric and may be challenging, multimodality imaging plays a pivotal role.

Learning objectives

• Multimodality imaging has a major role in the definite diagnosis of rare cases and to manage properly

• Treating RV thrombus with NOACs is a novel approach in ACM.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Conflicts of interest

There are no conflicts of interest.

Funding Statement

Nil.