Left atrial dominant cardiac sarcoidosis presenting with supraventricular tachycardia and left atrial myocardial damage: A case report

Abstract

A 61-year-old woman presented to our hospital with palpitations and dyspnea persisting for several months. Electrocardiography revealed atrial tachycardia, and X-ray revealed bilateral hilar enlargement. Computed tomography (CT) was performed for suspected sarcoidosis of the respiratory system, which revealed hilar lymph node enlargement in the bilateral lungs. ¹⁸F-Fluorodeoxyglucose (¹⁸F-FDG)-positron emission tomography-CT revealed abnormal ¹⁸F-FDG uptake in the hilar lymph nodes, liver, and left atrium (LA), but not in the left ventricle. Contrast-enhanced cardiac magnetic resonance imaging revealed late gadolinium enhancement (LGE) in the LA. Mediastinal lymph node, transbronchial lung, and right ventricular biopsies were performed, but no specific pathological findings were observed. Echocardiography-guided liver biopsy was also performed, which revealed non-caseating epithelioid granulomas. We definitively diagnosed systemic sarcoidosis, including cardiac lesions. Following the initiation of immunosuppressive therapy, abnormal ¹⁸F-FDG uptake in the liver, lymph nodes, and LA resolved, and atrial tachycardia improved, likely owing to the suppression of atrial inflammation. However, LGE in the LA persisted after immunosuppressive therapy, suggesting that structural damage had persisted. In this case, multimodality imaging helped us understand the disease state and post-treatment course.

Learning objective

The main site of cardiac sarcoidosis involvement is the left ventricle, and cases in which inflammation is confined to the left atrium are rare. In left atrial dominant cardiac sarcoidosis, clinical manifestations are often limited to supraventricular tachycardia. Although immunosuppressive therapy controlled the arrhythmia, multimodality imaging revealed that left atrial structural damage persisted, even after inflammation had improved. These findings highlight the clinical importance of recognizing left atrial dominant cardiac sarcoidosis, as irreversible atrial damage may persist despite adequate treatment.

Introduction

Sarcoidosis is a systemic inflammatory disease. In cardiac sarcoidosis, the ventricles are usually the primary sites of involvement. Accordingly, abnormalities in ventricular function or morphology, as well as ventricular arrhythmias, are regarded as key diagnostic indicators. However, when the main cardiac inflammatory lesion is confined to the left atrium (LA) without left ventricular abnormalities, the diagnosis becomes extremely challenging. Here, we present a rare case in which inflammation was confined to the LA rather than the left ventricle.

Case report

A 61-year-old woman presented to our hospital with palpitations and dyspnea persisting for several months. On physical examination, her heart rate was 139 beats/min and her blood pressure was 109/74 mmHg. B-type natriuretic peptide concentration was 316.0 pg/mL. Electrocardiography revealed atrial tachycardia (Fig. 1A), and X-ray revealed prominent bilateral hilar enlargement. Echocardiography demonstrated preserved left ventricular ejection fraction (64%) without regional wall motion abnormalities or left ventricular wall thinning. LA volume was increased (LA volume index: 53 mL/m²), while LA reservoir strain was reduced (−18.2%) (Fig. 1B). Computed tomography (CT) was performed for suspected sarcoidosis of the respiratory system, revealing hilar lymph node enlargement in the bilateral lungs. ¹⁸F-Fluorodeoxyglucose (¹⁸F-FDG)-positron emission tomography-CT (¹⁸F-FDG-PET-CT) revealed abnormal ¹⁸F-FDG uptake in the bilateral hilar lymph nodes, liver, and LA (Fig. 1C). Systemic sarcoidosis was suspected based on these findings. Serum angiotensin-converting enzyme activity was 32.5 U/L, and soluble interleukin-2 receptor concentration was 626 U/mL. Mediastinal lymph node and transbronchial lung biopsies were performed, but no specific pathological findings were observed. Therefore, we investigated the cardiac lesion using contrast-enhanced cardiac magnetic resonance (CMR). CMR imaging revealed late gadolinium enhancement (LGE) in the LA (Fig. 1D), but not in the left ventricle. We also performed right ventricular biopsy; however, histological findings of sarcoidosis were not obtained. Finally, echocardiography-guided liver biopsy was performed, which revealed non-caseating epithelioid granulomas (Fig. 2). We diagnosed systemic sarcoidosis involving cardiac lesions based on histological confirmation from liver biopsy and fulfillment of two major criteria for cardiac involvement: abnormal ¹⁸F-FDG uptake and delayed gadolinium enhancement of the myocardium. We initiated immunosuppressive therapy (corticosteroid, 30 mg/day). Atrial tachycardia resolved within a few days after treatment initiation, and no recurrence was observed.

Fig. 1.

Multimodality imaging at admission. (A) Electrocardiography showing atrial tachycardia. (B) LA reservoir strain was reduced (−18.2%). (C) ¹⁸F-FDG-PET-CT showing abnormal ¹⁸F-FDG uptake in the LA, liver, and bilateral hilar lymph nodes (white arrow). There was no abnormal uptake in the LV. (D) Contrast-enhanced CMR imaging revealed remarkable LGE in the LA (yellow arrow).

CMR, cardiac magnetic resonance; ¹⁸F-FDG, ¹⁸F-fluorodeoxyglucose; ¹⁸F-FDG-PET-CT, ¹⁸F-fluorodeoxyglucose-positron emission tomography-computed tomography; LA, left atrium/atrial; LV, left ventricle; LGE, late gadolinium enhancement.

Fig. 2.

Histopathological findings of liver biopsy. Scattered epithelioid cell granulomas were observed (red arrow), accompanied by inflammatory cell infiltration predominantly composed of lymphocytes admixed with eosinophils.

At 6 months after the initiation of immunosuppressive therapy, the patient no longer experienced palpitations, and 24-h Holter monitoring revealed no supraventricular arrhythmia. There were also no electrocardiographic findings suggestive of LA overload. We performed transthoracic echocardiography, CMR, and ¹⁸F-FDG-PET-CT. ¹⁸F-FDG-PET-CT demonstrated no abnormal ¹⁸F-FDG uptake in the lymph nodes, heart, or liver. However, transthoracic echocardiography showed that LA reservoir strain was persistently reduced at −17.8%, and LGE in the LA was unchanged (Fig. 3).

Fig. 3.

¹⁸F-FDG-PET-CT and contrast-enhanced CMR imaging before and after treatment. ¹⁸F-FDG-PET-CT (upper row) and contrast-enhanced CMR imaging (lower row) at baseline (A) and 6 months after treatment (B). Abnormal ¹⁸F-FDG uptake in the LA (white arrow) disappeared after treatment. However, the distribution of LGE in the LA did not change after treatment (yellow arrow).

CMR, cardiac magnetic resonance; ¹⁸F-FDG, ¹⁸F-fluorodeoxyglucose; ¹⁸F-FDG-PET-CT, ¹⁸F-fluorodeoxyglucose-positron emission tomography-computed tomography; LA, left atrium/atrial; LGE, late gadolinium enhancement.

Discussion

Sarcoidosis is an inflammatory disease of unknown etiology, and cardiac involvement typically affects the left ventricle and conduction system [1]. Therefore, heart failure, atrioventricular conduction disorder, and ventricular arrhythmia are major clinical findings in patients with cardiac sarcoidosis. In contrast, primary atrial involvement is uncommon in sarcoidosis. Several case reports have shown LA involvement associated with left ventricular lesions; however, cases with isolated LA or LA-predominant involvement are rare [2], [3], [4], [5]. In previous cases, supraventricular tachycardia and abnormal ¹⁸F-FDG uptake improved after immunosuppressive therapy. Similar to prior reports, our patient showed no abnormal ¹⁸F-FDG uptake in the LA after immunosuppressive therapy, and atrial tachycardia was resolved. Supraventricular tachycardia occurs in 32% of patients with cardiac sarcoidosis [6], and abnormal ¹⁸F-FDG uptake in the LA and increased LA volume are independent risk factors for supraventricular tachycardia [7]. Not only the LA, but a previous reported case also demonstrated that right atrium inflammation induced sinus node dysfunction and reentrant, typical cavotricuspid isthmus-dependent flutter [8]. Hasegawa et al. reported that areas of abnormal ¹⁸F-FDG uptake on PET corresponded to low-voltage regions on LA voltage mapping, whereas scarred regions were characterized by the absence of distinct electrograms in a LA sarcoidosis patient. They concluded that these pathological changes created the substrate for supraventricular tachycardia [5]. These findings suggest that atrial inflammation and structural remodeling are associated with supraventricular tachycardia in cardiac sarcoidosis.

At 6 months after the initiation of immunosuppressive therapy, LGE in the LA on CMR imaging persevered and LA reservoir strain remained low. These findings may indicate the presence of persistent LA structural abnormalities. Although the prognostic significance of LA LGE remains unclear, LA dysfunction has been reported to be associated with adverse clinical outcomes. Therefore, careful clinical follow-up is considered appropriate to monitor for recurrence of supraventricular tachycardia and the potential development of heart failure. In guidelines from the Japanese Circulation Society, there is no mention of supraventricular tachycardia and LA dysfunction in the diagnostic criteria or clinical findings for cardiac sarcoidosis [9]. It is important to recognize that LA dominant cardiac sarcoidosis exists, and histological evidence of extra-cardiac lesions plays a crucial role in identifying sarcoidosis when the LA is the only cardiac lesion. In the present case, we performed a liver biopsy for histological diagnosis. Taking into account the systemic involvement, clinical course, and multimodality findings, we concluded that sarcoidosis was the most plausible diagnosis based on an integrated and comprehensive assessment of all available clinical information. However, direct histological evidence of atrial involvement was not available. We could not completely exclude another atrial inflammatory disease or atrial cardiomyopathy, and this is a limitation of this case. A recent case report performed atrial septal biopsy for the diagnosis of sarcoidosis [10]. This approach may be useful, as atrial septal biopsy and catheter ablation for supraventricular arrhythmia can be performed in the same session. In the present case, atrial septal biopsy was not performed because we achieved good control of atrial tachycardia using immunosuppressive therapy alone.

In summary, we report a rare case in which LA dominant cardiac sarcoidosis was diagnosed by liver biopsy, and the disease state and post-treatment course of the LA were effectively monitored using multimodality imaging.

Consent statement

Written informed consent was obtained from the patient to publish this case report, including accompanying images.

Declaration of competing interest

The authors declare that there is no conflict of interest.