It has been found by the researchers at the UK's first dedicated cardio-oncology clinic that impaired heart function is common to both treated and untreated cancer patients. A research concluding the same was presented at the recently held EuroEcho-Imaging 2015 seminar. It states the possibility that cancer itself may damage heart muscle irrespective of exposure to cancer drug therapies. The annual meeting of the European Association of Cardiovascular Imaging (EACVI), a registered branch of the European Society of Cardiology (ESC) was recently held in Seville, Spain.
Dr. Rajdeep S. Khattar, consultant cardiologist at the Royal Brompton Hospital in London, UK and last author of the abstract opined that it is well known that chemotherapy is potentially toxic to the heart, making cancer patients more prone to cardiovascular complications such as heart failure, hypertension or myocardial ischaemia. He added that the study is significant as it raises the possibility that tumour growth itself may also damage the heart which could have important implications for monitoring.
Cardiotoxicity is defined based on a reduced ejection fraction (less than 55%) and symptoms of heart failure. Echocardiography is needed to assess ejection fraction – coarse measure of left ventricular function. In simple words, it refers to the percentage of blood pumped into the circulation when the heart contracts. For an example, say there is 100 ml of blood in the left ventricle and 60 ml is pumped out, the ejection fraction is said to be 60%.
For this study, the researchers applied an even more subtle measure of left ventricular function using echocardiography called strain. This measure indicate how well the myocardial fibres contract. It has been known from previous studies that cancer patients who have undergone chemotherapy may have a normal ejection fraction but reduced strain and that this may be the onset of subsequent cardiotoxicity. Khattar remarked that through their study they wanted to see if cancer patients who have not been through chemotherapy and have a normal ejection fraction, can have reduced strain measurements.
As a part of the study, myocardial strain in three groups with a normal ejection fraction (55% or more) were compared: 43 patients with cancer who were currently being treated or had received treatment in the past, 36 patients with as yet untreated cancer, and 20 healthy individuals matched to the cancer groups for age and gender. The study revealed that both groups of cancer patients had similarly reduced strain measurements which indicated impaired heart function as compared to the healthy individuals.
Dr. Khattar said that it is interesting to note that all the cancer patients had a preserved ejection fraction. So, if one went by that coarse measure their hearts were functioning normally. However, the strain measurements indicated that they did have myocardial dysfunction. This finding is something new and it needs to be taken into account with all seriousness while treating cancer patients. It raises the possibility that the tumour itself may have a significant undesirable effect on the function of the heart.
Dr. Khattar said that patients with reduced strain before they start their cancer drug therapies may be predisposed to developing heart failure during the course of their treatment and hence there is a need for closer monitoring in such patients. It will be a real change as presently it is not mandatory for them to have a cardiovascular risk assessment by a cardiologist.”
The patients in the current study will be followed upon by the researchers in the days and years to come to find out if their rates of heart failure and death are predicted by the strain measurements. Dr. Khattar opined that if it turns out that the patients with reduced strain prior to cancer treatment are more prone to heart failure and death then implementing closer monitoring of patients with cancer will be of great importance.
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