Echo Case: A 54 year old man with new onset ventricular fibrillation

Authors:

Kan Liu, MD, PhD, Jamal Ahmed, MD, David Feiglin, MD

Affiliations of Authors:

State University of New York, Upstate Medical University Hospital, Syracuse,

Corresponding author:

Kan Liu, MD, PhD, Division of Cardiology, State University of New York, Upstate Medical University, 90 presidential plaza, Syracuse, NY 13202, USA; Tel: 315-464-4535; 315-464-1931 (office); Fax: 315-464-1938 (Fax); Email: liuk@upstate.edu

Author contributions: KL, JA and DF all collected the data and wrote the manuscript.

CLINICAL INTRODUCTION 

A 54-year-old man without significant medical history presented with sudden onset chest discomfort and multiple episodes of ventricular fibrillation requiring external defibrillation and cardiopulmonary resuscitation. Coronary angiography ruled out significant artery stenosis. Both ventriculography and echocardiography revealed decreased left ventricular ejection fraction (25%). On examination, he was hemodynamically stable. The lungs were clear to auscultation and there was no jugular venous dilation. The cardiac examination revealed a regular rate and rhythm without murmur. Cardiac magnetic resonance (CMR) and 18F-2-Fluoro-2-Deoxyglucose positron emission tomography (FDG-PET) images were shown (Figure 1).

QUESTION

Which of the following would be the next best step?

1. Implantable loop recorder
2. Electrophysiologic testing for radiofrequency catheter ablation
3. Endomyocardial biopsy
4. Genetic testing

ANSWER

1. Endomyocardial biopsy

This patient developed new onset malignant ventricular arrhythmia, so cardiac imaging was warranted to uncover structural heart disease. CMR showed delayed myocardial gadolinium enhancement in the basilar inetrventricular septum (Figure 1A). In FDG-PET, increased glucose uptake was found in more myocardial regions, including basal to middle/distal interventricular septum, and middle anterolateral wall (Figure 1B).

Figure 1. Cardiac magnetic resonance with a T1-weighted inversion recovery image (A) and 18F-2-Fluoro-2-Deoxyglucosepositron emission tomography (B) in a 54 year old man with new onset ventricular fibrillation.

These imaging findings were suggestive of cardiac sarcoidosis (CS).  In a patient with ventricular fibrillation storm, continuous ambulatory monitoring with an implantable loop recorder is unnecessary.  Electrophysiology testing explores the mechanisms of induced or spontaneous ventricular arrhythmias to guide radiofrequency catheter ablation (Figure 2).

Figure 2. Electrophysiology testing explores the mechanisms of induced or spontaneous ventricular arrhythmias to guide radiofrequency catheter ablation.

It is not the first-line diagnostic approach, and only indicated for idiopathic and refractory ventricular arrhythmias.  Although many gene polymorphisms have been identified in patients with inherited cardiac channelopathies, such as long QT syndrome, Brugada syndrome, and catecholaminergic polymorphic ventricular tachycardia, the genetic heterogeneity of these disorders limits the diagnostic value of genetic testing.

Clinically recognized in about 5% of patients, CS is found in up to 30% at autopsy (1).  It can occur concurrently with other organ involvement or in isolation. Cardiac involvement independently predicts mortality, and poor prognosis underscores the need for early diagnosis/treatment.  Nevertheless, the onset of CS is variable. Ventricular arrhythmia can be the initial manifestation in a previously asymptomatic patient. Advanced imaging, CMR and FDG-PET, has been increasingly utilized in diagnostic approaches (2, 3). Although CMR can identify late gadolinium enhancement in T1-weighted images to show fibrosis/scar that represents chronic rather than active disease, FDG-PET detects myocardial metabolic abnormality by measuring the perfusion-metabolism mismatch of rubidium-82 and FDG, therefore being more sensitive to identify early-stage CS. Of note, these imaging features of CS are only suggestive and not disease specific. Endomyocardial biopsy (EMB) is needed to differentiate CS and other inflammatory myocardial disorders, such as idiopathic giant cell myocarditis (IGCM), which has a significantly different response to immunosuppressive agents and poorer prognosis. CS predominantly affects the left ventricular free wall and basilar interventriculr septum which are not bioptome-reachable, limiting the diagnostic value of EMB (4). However, in this patient, FDG-PET showed that sarcoidosis involvement had extended to middle/distal interventricular septum (Figure 1B). With this guidance, EMB successfully obtained diseased myocardial specimens. The histological examinations showed non-necrotizing granuloma and immunohistochemical study (with CD4 and CD8 antibodies) distinguished CS from IGCM (Figure 3) (5).

Figure 2. Histological examinations (A: 100X; and B: 400X) showing multinucleated giant cells with surrounding lymphocytic/eosinophilic infiltration. Arrows: non-necrotizing granulomas.  Immunohistochemical analysis (C: 200X, stained with CD8 antibodies; and D: 200X, stained with CD4 antibodies) showing sparse CD8 positive T cells (C), and numerous CD4 positive T cells (D) in the periphery of the granulomas.

 Reference

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