Pericardial Agenesis as a Rather Unusual Cause of Palpitations: We Only See What we Know.

Cardiac palpitations secondary to ventricular ectopic beats are a frequent clinical indication for a cardiac magnetic resonance (CMR) scan. CMR has already demonstrated its additive diagnostic value in patients with frequent arrhythmias even when echocardiogram appears normal. Hereby, we describe a case of a middle-aged male patient referred to our laboratory because of frequent ventricular ectopic beats and an inconclusive echocardiogram due to an extremely poor acoustic window. A diagnosis of pericardial agenesis (PA) was made explaining patient symptoms and arrhythmias previously detected. Furthermore, at the case report description, PA prevalence, associated cardiac pathologies, and novel CMR diagnostic criteria are being described.

INTRODUCTION

Cardiac palpitations secondary to ventricular ectopic beats are frequently a clinical indication for a cardiac magnetic resonance (CMR) scan. CMR has already demonstrated its additive diagnostic value in patients with frequent arrhythmias even when echocardiogram appears normal. Normal CMR query in these patients is either arrhythmogenic right ventricular cardiomyopathy or an ischemic or nonischemic left ventricular cardiomyopathy.

CASE REPORT

A 66-year-old male patient, symptomatic for palpitation, underwent a 24-h electrocardiography Holter monitoring, showing frequent ventricular ectopic beats. Transthoracic echocardiography was deemed incomplete due to a very poor acoustic window and was therefore referred for a CMR scan.

Scout images [Figure 1a] immediately showed a levorotation of the heart, raising the suspicion of pericardial agenesis (PA). Axial and short-axis cine stack [Figure 1b and c] and fast spin echo inversion recovery images [Figure 1d and e] confirmed the suspicion revealing a partial absence of pericardial layers in the left lateral wall. No evidence of cardiac herniation was seen. CMR protocol was then modified to assess the presence of associated congenital abnormalities described in scientific literature. Aortic valve was tricuspid, and no evidence of atrial or ventricular septal defect or patent ductus arteriosus was seen with normal Qp/Qs, normal biventricular dimensions and systolic function and no myocardial fibrosis [Figure 1f]. The extreme rarity of PA accounts for the absence of studies and clear diagnostic criteria. The biggest population of PA patients studied with CMR (9 patients) by Macaione et al.[1] demonstrated the diagnostic value of whole-heart volume change (WHVC), expressed as the systodiastolic change of volume measured in axial cines, showing that a >13% threshold has an absolute diagnostic accuracy with sensitivity and specificity of 100%. WHVC of our patient was 25%, additional evidence of PA diagnosis.

Figure 1

Scout images (a) showing cardiac levorotation; axial (b) and short-axis (c) cine stack and fast spin echo inversion recovery images (d and e) confirming suspicion and revealing a partial absence of pericardial layers in the left lateral wall without evidence of cardiac herniation; T1-weighted gradient echo late gadolinium enhancement sequences (f) showing the absence of myocardial fibrosis

PA is an extremely uncommon congenital cardiac disease with a prevalence of <1:10000.[2] It can be complete or partial, and it may be associated with other congenital abnormalities such as atrial septum defect, patent ductus arteriosus, or bicuspid aortic valve.[3] CMR represents the noninvasive diagnostic gold standard of this unusual pathology albeit a high level of suspicion is necessary to avoid underdiagnosis.

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Conflicts of interest

There are no conflicts of interest.