Discussion
Our single-center study confirms very good overall accuracy of TTE in CM diagnosis. This is clinically important as accurate assessment of cardiac masses is essential for appropriate clinical management and treatment of these patients.
Diagnosis of CM can be challenging since patients are frequently asymptomatic or have only non-specific signs and symptoms. Dyspnea, a frequent and non-specific symptom of cardiac disease, was the most common complaint in our CM group, which is consistent with previous reports [9–11]. Clinical presentation itself rarely suggests the diagnosis of CM; therefore, cardiac imaging is essential in the evaluation of patients with suspected CM. Echocardiography is the most widely used imaging modality that provides important information about the location, size, and appearance of the cardiac mass, as well as possible complications (e.g. obstruction). Previous studies have shown that CM are typically solitary, located in the left atrium, smooth in surface and mobile [12,13]. However, the morphological presentations of CM are often atypical and heterogeneous, leading to overlap with other NM cardiac tumors and cardiac masses.
The results of our study show very good overall accuracy (85%) of TTE in CM diagnosis with excellent sensitivity (97%). However, the specificity of TTE is modest (50%) and caution is warranted as misdiagnosis of CM is possible. In our study, 5 of the misdiagnosed cases of CM were actually papillary fibroelastoma, which is also a common primary benign cardiac tumor. One of the suspected CM was actually a metastasis of malignant melanoma, underlying the importance of surgical excision and pathohistological examination of all suspected CM.
According to our results tumor localization and tumor size are the best echocardiographic characteristics to distinguish between CM and NM cardiac tumors. CM are typically located in the left atrium attached to the interatrial septum at the region of fossa ovalis, which was also shown in our study [14]. In our patients, 72% of CM were located typically. However, all tumors preoperatively misdiagnosed as CM were located in atypical locations, such as the right atrium and left ventricle. Tumors in the NM group were also significantly smaller compared to tumors in the CM group. However, there was no significant difference in age, sex, and other echocardiographic characteristics (mobility and surface) between the groups.
The differential diagnosis of CM is broad and definite diagnosis is crucial, as treatment varies depending on the diagnosis. Multimodality cardiac imaging improves the diagnostic accuracy of different cardiac masses. In the majority of our patients, at least one additional imaging modality was used as a part of the diagnostic workup. TEE improves image quality and provides more morphological information than TTE [15]. Computed tomography and cardiac magnetic resonance provide additional information on topographic relationships and tissue characteristics, and may detect other pathological conditions within the thorax [16,17]. Assessment of cardiac tumors by CMR is more accurate than echocardiography and can reliably distinguish between benign and malignant cardiac tumors [18–20].
There are some limitations to this study. First, this is a retrospective study with a relatively small study population. However, the population size is comparable to other studies on CM. Due to the low incidence of cardiac tumors, only multicenter studies can provide a larger scale patient population. Second, preoperative echocardiography was performed by different echocardiographers, potentially exposing the results to inter-investigator variability in determining the diagnosis. Due to the study inherently including participants already given a working diagnosis of CM, any cardiologist performing TTE was likely influenced by the information provided upon referral. A larger, multicenter, prospective study could serve to identify echocardiographic and clinical characteristics specific to CM, as well as other cardiac tumors, further increasing the utility of preoperative diagnostic modalities.