Cardiac metastasis are uncommon. Literature reviews for cardiac metastasis dating from 1948–2007 show that the incidence of cardiac metastasis ranges between 2.3–18.3%. The highest incidence was noted by Hanfling in 1960 who reported an autopsy series comprising of 127 cases of cardiac metastasis in cancer patients with an incidence of 4.8% of all autopsies and 18.3% of all cancer related deaths. More recent studies from 2005–2007 show an incidence of 2.3–9.1%. An important consideration is that cardiac metastasis may be underestimated due to being clinically silent. [2, 3] The postulated mechanisms of cardiac metastasis include direct extension, hematogenous dissemination, lymphatic spread or by intra-cavitatary spread via the superior/ inferior vena cava. The highest rates of cardiac metastasis have been reported with pleural mesothelioma, melanoma and lung. [3]
On our literature review, we found a total of 31 cases of metastatic cardiac involvement secondary to colorectal cancer. The patients ranged from 41–81 years with a median age of 70 years at diagnosis of metastasis. There is an overall male preponderance with 21 males vs 10 females reported thus far.
When symptomatic, cardiac metastases usually present with clinical features of heart failure including dyspnea, palpitations, thromboembolism or tumor extension into the superior or inferior vena cava manifesting with edema or obstructive signs. [4, 5]
The differential to be considered when evaluating cardiac masses includes malignancies, atrial myxomas, thrombi and vegetations. Streptococcus gallolyticus infective endocarditis has been associated with colorectal malignancies. Various imaging modalities including transthoracic/ transesophageal echocardiography, CT or MRI can be utilized to provide a comprehensive view of the lesion and identify potentially infiltrative cardiac tumors. Molecular profiling of the metastatic tumor may help tailor the therapy and should be considered as part of the workup. Although colonoscopy is part of the initial workup for primary colon cancer; it should also be considered in patients who present with metastatic colorectal cancer to evaluate for a second primary colorectal carcinoma, as done for our patient. Henceforth, it would be plausible to consider further evaluation for cardiac involvement in any patient with a history of malignancy presenting with cardiopulmonary symptoms.
Metastatic cardiac tumors are generally associated with an aggressive disease course and a generally poor outcome. Only 9 out of the 31 reported cases of metastatic colorectal carcinoma to the heart were alive at the time of the case being reported. However, given the latest developments in diagnostic and therapeutic modalities, increased awareness and higher accessibility to health care over the years; it has become easier to identify these rare metastases.
In the event that an isolated metastasis or oligometastatic disease is found; multiple treatment options including surgical resection and chemotherapy may be offered. However, the ultimate decision would be contingent upon disease volume, tumor burden, comorbidities, genetic profiling and individualizing risk versus benefits for the patient. Surgery may be considered in a case of solitary cardiac metastasis or as a debulking maneuver if the lesion causes hemodynamic instability to bridge to ultimate treatment with chemotherapy. Upfront chemotherapy may be the best treatment for other patients. There is no consensus on treatment of cardiac metastasis and further studies are required to outline optimal treatment strategies for these patients.
Amongst the various treatment modalities that were used in the various cases reported; 14 patients underwent surgery only, 3 underwent chemotherapy only, 4 had surgery followed by chemotherapy, 9 received no treatment, treatment was not available for 2 of the reported cases.
Treatment with chemotherapy only in these patients with metastatic colorectal cancer lead to variable response to treatment but the patients invariably had ultimate disease progression or recurrence. Choufani et al reported a case of patient who was 16 months post completion of treated metastatic colorectal cancer to the liver. This patient presented with new onset abdominal distension and dyspnea on exertion and was noted to be having a right atrial mass along with progression of liver metastases, new findings of ascites and pleural effusions. He received four doses of Irinotecan monthly with complete resolution of right atrial mass and ascites. However, subsequent CT scans showed partial recurrence of the right atrial mass and rising CEA levels. Overall, the patient was doing well symptomatically 10 months after resumption of irinotecan. [6] Pontillo et al reported a case of Right atrial mass noted incidentally as part of pre-operative cardiac evaluation seven years following her previous diagnosis and treatment for CRC. She was also noted to be having peritoneal carcinomatosis and was treated with standard medical therapy. No specific names or duration of treatment was mentioned. [7] Meanwhile the case reported by Tsuji involved an incidentally diagnosed RV tumor with colonoscopy confirming wild type KRAS on histopathological examination. The tumor was deemed inoperable by surgeons and the patient was found to be having metastatic lung involvement as well. The patient received 10 cycles of 5-fluorouracil, oxaliplatin plus panitumumab. Oxaliplatin was held thereafter due to neuropathy and was deemed to be in partial response after 12 courses (10 months after initial treatment). However, follow up CT after 15 cycles showed progressive disease in the heart and the patient eventually elected for palliative care but was alive 2 years after his diagnosis. [8]
Amongst the four cases with surgery followed by chemotherapy, two patients received bevacizumab-based treatments. Bianchi et al reported a case with hyper-metabolic focus noted on PET/ CT in the Right Atrium following mildly elevated CEA levels at 35 ng/ml on routine surveillance 2 years out of treatment completion for colorectal cancer. Patient underwent a minimally invasive thoracotomy with mass excision which revealed the metastasis. He was received 1 cycle of leucovorin, fluorouracil and irinotecan (FOLFIRI) and bevacizumab but was unable to tolerate the subsequent sessions. Patient died 3 months later due to massive pulmonary embolism. [9] However, since the patient received only one cycle, it is uncertain to assess whether the patient could have had potential response to treatment. The patient reported by Butler et al was noted to be having a mass in right atrioventricular groove on a CT scan/ TTE following elevated CEA levels 17 years following her initial diagnosis and treatment. The patient underwent cardiac surgery and resection. Follow up PET/ CT in 6 months after surgery showed extension of neoplastic disease in her left and right atria. Gene markers reportedly showed sensitivity to chemotherapy; however specifics regarding which markers were checked is not mentioned. The patient was treated with FOLFOX only initially; then bevacizumab was added. And 2.5 years since diagnosis of cardiac metastasis, she was placed on single agent bevacizumab without disease progression. [10] This case was similar to ours with regards to choice of treatment agents and response noted. In another case report by Namireddy et al, the patient presented with shortness of breath and syncope; 1 year after treatment for T3N1 rectal adenocarcinoma and was found to be having right atrial mass and moderate pulmonary embolism. The patient underwent median sternotomy with wide excision of the right atrial wall and was started on chemotherapy but no comments were noted with regards to the choice of the regimen or patient’s response to treatment. [11] de la Fouchardière et al reported a patient who was 3.5 years post diagnosis for rectal cancer, the patient’s CEA levels were found to be up trending which prompted a PET/ CT scan which showed a 6 cm x 3 cm mass in the RV. The patient underwent cardiac surgery with palliative resection and subsequent pathology report revealed an adenocarcinoma confirming rectal origin. A post-operative CT scan showed residual intracardiac mass with pericardial effusion. He received 6 cycles of FOLFIRINOX after which the heart mass was noted to be stable and the pericardial effusion decreased. The patient completed a total of 11 cycles of FOLFOX. Patient asymptomatic throughout. [12]