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Interact CardioVasc Thorac Surg 2007;6:479-483. doi:10.1510/icvts.2007.154096 © 2007 European Association of Cardio-Thoracic Surgery
Cardiac myxoma: preoperative diagnosis using a multimodal imaging approach and surgical outcome in a large contemporary series
a Department of Cardiothoracic Surgery, Mount Sinai School of Medicine, 1190 Fifth Avenue, New York, NY 10029-1028, USA Received 13 February 2007; received in revised form 14 May 2007; accepted 15 May 2007
*Corresponding author. Tel.: +1 212 659 6820; fax: +1 212 659 6818.
Diagnosis of cardiac myxoma is typically suggested in the presence of symptoms and echocardiographic findings of an intracardiac mass and confirmed histologically. Coronary angiography (CA) and cardiac magnetic-resonance-imaging (MRI) may provide specific additional information which could lead to a precise preoperative diagnosis. Herein we report a series of 28 patients who underwent excision of myxoma between 1998 and 2005. Data analysis included patient demographics, clinical presentation, imaging modalities, and operative outcome. Echocardiography revealed an intra-atrial mass in all patients but did not differentiate between myxoma and other formations such as thrombi. CA showed neovascularization suggestive of cardiac tumor in 12 (53%) patients. MRI demonstrated specific characteristics of myxomatous tissue in all cases. Surgical removal was performed with no hospital mortality or major complications. Mid-term survival was similar to that of the general population. In patients with a cardiac mass, echocardiography remains the first diagnostic imaging modality but does not allow definite discrimination between cardiac tumors and thrombi. CA shows neovascularization in 50% and has, therefore, a low sensitivity and specificity in distinguishing the nature of the mass. MRI shows specific tissue characteristics facilitating the diagnosis of myxoma preoperatively. Surgery should be performed promptly and this can provide excellent early and mid-term results.
Key Words: Cardiac myxoma; Diagnostic approach; Magnetic resonance imaging; Cardiac surgery; Outcome
Cardiac myxomas are benign tumors of the heart [1]. Eighty-five percent are located in the left atrium (LA), the remaining 15% in the right atrium (RA), in both atria, or occasionally in the ventricles [2]. Clinical symptoms are related to embolic events or obstructive valvular dysfunction [1]. Approximately 10–15% of patients are asymptomatic and the diagnosis is made incidentally [1, 3]. The most common differential diagnosis of atrial myxoma is thrombus formation [1]. Echocardiography is usually the first imaging modality to detect a cardiac mass. The echocardiographic localization of the mass and eventual clinical symptoms may be strongly suggestive of myxoma in the light of potential differential diagnosis such as thrombi. A few previous publications have reported on the usefulness of coronay angiography (CA) in further defining the diagnosis of myxoma by demonstrating signs of neovascularization [4, 5]. More recently it has been suggested that cardiac magnetic resonance imaging (MRI) may play a significant role by demonstrating specific findings in favor of myxoma. Herein we describe a large series of patients with cardiac myxoma. An emphasis is made on the diagnosis, particularly on the findings of different imaging modalities such as echocardiography, CA and MRI. We also report our surgical experience with early and mid-term outcome.
Patients with a cardiac tumor were retrospectively identified using our computerized cardiac surgery database. Patients with a diagnosis of myxoma were included. The protocol was approved by our institutional review board and a waiver of informed consent was obtained. Hospital charts were reviewed for pre-, intra-, and postoperative variables. Information on late survival was obtained from the web-based social security death index (http://ssdi.rootsweb.com). Normally distributed continuous variables are presented as mean±standard deviation (S.D.) and otherwise as median and interquartile range (IQR). Categorical variables are shown as percentage of the sample. The survival curves of myxoma patients were compared with the expected survival of age- and sex-matched actuarial data from the 2003 US population and tested by using the one-sample log rank test. All statistical tests were performed with SPSS for Windows version 15 (SSPS Inc, Chicago, IL).
3.1. Patient characteristics Between January 1998 and December 2006, fifty-one patients underwent surgery for cardiac mass. Twenty-eight (55%) had a cardiac myxoma whereas the remaining 23 patients had other tumors (renal cell carcinoma (n=3), fibroelastoma (n=3), rhabdomyosarcoma (n=2), angiosarcoma (n=3), and other (n=8)). The median age was 62 (range 29–90) years and 18 (64%) patients were female. Table 1 summarizes patient characteristics.
3.2. Clinical presentation Eighty-two percent of patients presented with symptoms of the triad of intracardiac obstruction, peripheral embolism or constitutional symptoms (Table 1) [1]: Constitutional symptoms were present in 15 (54%) patients and included fever (n=5), fatigue (n=12), and weight loss (n=7). Symptoms due to intracardiac valvular obstruction were present in 15 (54%) patients. Three patients presented with congestive heart failure due to RA mass obstructing the tricuspid orifice. Eight patients were evaluated for recurrent syncopal events related to LA mass. Moderate-to-severe mitral regurgitation was present in two patients. Dyspnea or chest pain was noted in four patients secondary to mitral valve obstruction. Peripheral embolization occurred in six (21%) patients (myocardial infarction (n=1); neurologic event (n=5)). In asymptomatic patients, diagnosis was either incidental (n=3) or after the detection of a systolic murmur (n=2). 3.3.1. (A) EchocardiographyTransthoracic and transesophageal echocardiography were performed in all, and eight patients, respectively. Echocardiography revealed LA and RA mass in 24 (86%) and 4 (14%) patients, respectivley. Among LA masses, 18 (75%) were pediculated and mobile, while six (25%) were broad-based and sessile. The majority (n=19, 79%) of LA masses arose from the inter-atrial septum (Fig. 1a), and three (13%) were inserted on the lateral wall. In two (8%) patients, the mass was attached to the anterior leaflet of the mitral valve causing mitral regurgitation. All RA masses inserted at the inter-atrial septum and were large and mobile, leading to a subtotal tricuspid orifice obstruction (Fig. 1b). These echocardiographic findings were suspicious for atrial tumors, particularly myxoma, but could not differentiate precisely between myxoma and other cardiac masses (e.g. thrombi or other tumors).
3.3.2. (B) Coronary angiography CA was performed in 23 (82%) patients to rule out concomitant coronary artery disease (CAD). In six (26%) patients significant CAD was found leading to percutaneous angioplasty and stent placement in three patients, and surgical revascularization during mass excision in the remaining three patients. Angiography showed neovascularization of the mass in 12 (52%) cases with an origin from the left circumflex artery (Fig. 2a) in eight patients and from the right coronary artery (Fig. 2b) in four patients. This finding of neovascularization strongly suggested a cardiac tumor without determining its exact nature.
3.3.3. (C) MRI MRI was performed in three patients to obtain further information following the diagnosis of intra-atrial mass. MRI showed hypointensity of the mass relative to the myocardium on T1-weighted cine images (Fig. 3a) and hyperintensity on T2-weighted images (Fig. 3b) in all patients. These findings are in favor of a tumor with high extracellular water content, which is typical for myxomatous tissue. Furthermore, MRI showed a heterogeneous appearance of the mass, demonstrating areas of necrosis, hemorrhage and calcification. Finally, gadolinium-enhanced MRI demonstrated mass-perfusion in all cases (Fig. 3c,d). These findings of specific characteristics of myxomatous tissue with heterogenous appearance and neovascularization suggest the diagnosis of myxoma.
3.4. Surgical management Cardiopulmonary bypass was instituted between the ascending aorta and both venae cavae. After cardioplegic arrest, the LA was entered through the Sondergaard's groove, whereas the RA was opened following a transverse right atriotomy. LA masses were resected with a 2-mm margin and a frozen section was obtained to determine the diagnosis. Patch closure of the inter-atrial septum with autologous or bovine pericardium was performed in 13 patients, while the septal defect was closed primary in 11 patients. In two patients, the myxoma involved the annulus and the anterior leaflet of the mitral valve leading to mitral valve replacement. RA myxomas were also completely excised followed by primary closure of the inter-atrial septum. Additional procedures were performed in 12 (43%) patients (Table 2).
3.5. Pathology Cardiac myxomas appeared macroscopically polypoid (n=23, 82%) or villous (n=5, 18%). Histological analysis revealed myxomatous tissue with acid-mucopolysaccaride matrix and polygonal cells in all patients (Fig. 4).
3.6. Surgical outcome There was no in-hospital mortality. Transient atrial fibrillation occurred in two patients. There were no other complications. In patients with preoperative neurologic event no worsening of symptoms occurred postoperatively. The median length of stay was 6.1±2.3 days. Three patients (all >70 years) died of unknown causes 2–4 years following surgery. The mid-term survival was similar to the expected survival of age- and sex-matched population (Fig. 5).
4.1. Preoperative diagnosis Echocardiography is usually the first imaging modality which leads to the diagnosis of a cardiac mass. It provides information about its size, localization and mobility. However, echocardiographic findings are not specific and discrimination between primary cardiac tumors, such as myxoma, and other cardiac masses remains challenging [6]. The most common differential diagnosis of cardiac myxoma is atrial thrombi [1, 7]. Clinical symptoms may be similar particularly with respect to intracardiac obstruction and peripheral embolization. In addition, atrial thrombi frequently mimic echocardiographic features of atrial myxoma making an accurate diagnosis difficult [6]. The precise determination of the nature of the mass is important because treatment modalities vary depending on etiology. Cardiac myxoma requires surgical intervention whereas thrombus formation may be completely resolved with appropriate anticoagulation therapy. Furthermore, the use of anticoagulation may potentially be harmful with increased risk of peripheral embolization in the presence of a cardiac tumor [8]. CA may be a useful tool in further differentiating between cardiac tumor and thrombi. Cardiac tumors such as myxomas are considered highly vascularized. This neovascularization can be depicted by CA. Van Cleemput et al. reported a 37% (n=7) rate of neovascularization in a series of 19 patients with cardiac myxoma [9]. Similarly, Furedi et al. reported signs of neovascularization in five out of nine (56%) cardiac myxoma patients [10]. These findings are in accordance with our study, in which 23 patients underwent CA and signs of neovascularization were only present in 12 (52%) of them. These findings of neovascularization were in favor of tumoral nature of cardiac mass allowing differentiation from atrial thrombi. However, in 11 (48%) patients no signs of neovascularization were detected, despite the fact that postoperative histological studies confirmed the diagnosis of myxoma in all cases. Therefore, the value of CA in differentiating cardiac masses between tumors such as myxoma and thrombi remains limited. Despite the lack of sensitivity and specificity, some authors have, however, suggested that CA should be performed systematically in patients with cardiac myxoma to detect a large supplying vessel [4]. We believe that CA is of limited interest in determining the etiology of an intracardiac mass. CA should only be performed in selected patients, particularly those over the age of 40 years and those with atherosclerotic risk factors undergoing surgical removal of a cardiac mass. In our experience, applying a multimodal diagnostic approach, cardiac MRI has played a major role in providing additional information regarding the diagnosis of myxoma. MRI provides information with respect to localization, insertion-site, and size of the mass. In addition, it provides specific information about tissue characteristics that facilitate the differentiation between myxoma and thrombi. Hypointensity in T1-weighted images relative to the myocardium, and hyperintensity in T2-weighted images, demonstrating tissue with high extracellular water content are commonly observed in myxomas (Fig. 3a,b). These findings are characteristic of myxomas and differentiate them from other tumors which show different signal intensity [11]. In addition, myxomas typically show a heterogeneous appearance in MRI, due to areas of necrosis, hemorrhage or calcification. In gadolinium enhanced MRI, myxomas generally show a heterogenous pattern of contrast enhancement due to high neovascularization. In contrast, atrial thrombi have a brighter appearance than tumor or myocardium in images with short inversion time, and a darker appearance in images with long inversion time (Fig. 6), and almost never show contrast enhancement in terms of neovascularization [11]. Cardiac computed tomography (CT) is increasingly used for noninvasive CA and may be an alternative modality for the assessment of cardiac masses. CT allows for the acquisition of images with excellent spatial resolution in a single 10–20 s breath-hold. However, MRI offers superior temporal resolution and soft tissue characterization, an invaluable ability in the evaluation of cardiac masses. Additional advantages of MRI include the absence of ionizing radiation and of nephrotoxic contrast agents.
The specific findings of tissue characteristics and neovascularization in addition to anatomical findings and clinical symptoms suggest strongly the preoperative diagnosis of cardiac myxoma in all patients. Therefore, at the present time, in patients with an intracardiac mass detected by echocardiography, MRI should be performed in order to determine the exact nature of the mass, which may facilitate the choice of appropriate therapeutic approach. In patients with diagnosis of myxoma a surgical intervention is strongly recommended, whereas in patients with cardiac thrombus, a period of anticoagulation therapy may be warranted. We report excellent results following the removal of myxoma with no operative mortality, no major morbidities and a mid-term survival similar to that of the general population. This is in accordance to most recent publications. However, some previous large studies (including 30–70 patients) have reported an operative mortality of 3–4% [12, 13] and major postoperative complications such as stroke [12], cardiac tamponade [14] and respiratory failure [15]. It has to be mentioned that, because of the rarity of the disease, most of these studies have included patients over three or even four decades and probably most of these complications have occurred during the early phase of the clinical experience. The excellent results observed in studies such as ours, indicate that improvements in perioperative management and postoperative care of patients undergoing cardiac surgery have impacted positively on the outcome of surgery following the removal of myxoma. Today surgical removal of myxoma can be performed with excellent results even in combination with additional procedures such as valve surgery or coronary revascularization. Surgery should, therefore, be performed promptly after the diagnosis is made to avoid potential complications such as peripheral embolization or cardiac valvular obstruction.
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Abstract
1. Introduction
