Cancers May Impair Heart Function, Even Without Chemo: More Evidence
More research is suggesting a possible relationship between cancer itself and the development of CHD.
In a new study of 99 total participants with normal ejection fraction (LVEF >55%), myocardial dysfunction, as shown with reduced strain measurements, was similar between patients with cancer who did and did not take cancer drug therapies. In addition, the strain rates for both groups were significantly lower than age- and sex-matched healthy individuals without cancer (P<0.05).
These findings were presented in Seville, Spain last week at the European Society of Cardiology"s EuroEcho-Imaging 2015meeting. "Under conventional definitions, these patients didn"t have cardiotoxicity, because they had normal ejection fraction and no history of any cardiac problems," senior author Dr Rajdeep S Khattar (Royal Brompton Hospital, London, UK) told heartwirefrom Medscape. "But these patients had reduced strain, which looks at how well myocardial fibers contract and indicates a degree of subclinical dysfunction," he said.
As reported by heartwire , a recent study of 500 untreated cancer patients showed high baseline levels of high-sensitivity troponin T and five CV neurohormones — all of which increased as tumor growth progressed. "Our two studies line up," said Khattar. "We could hypothesize that the tumor releases some of these biomarkers that affect the heart. And then we showed that indeed there does appear to be some substrate effect on myocardial function. But more studies are needed into these possible associations."
Khattar said he helped start the first dedicated cardio-oncology clinic in the UK. "Cancer survival rates are improving, and patients are living longer." But because of this, adverse events from chemotherapy treatments are becoming more evident, including cardiac outcomes, he said. "There has been an increasing interest in this area. But in the past, there"s not been much collaboration between cardiologists and oncologists to assess these patients in a more protocolized, routine manner," said Khattar. "We wanted to see if we could identify, through heart monitoring, those we think may be at increased risk even before they"ve received chemotherapy."
The investigators enrolled 79 patients (62% women; mean age 58 years) who were diagnosed with cancer. Of these, approximately 30% had breast cancer, 30% had lymphomas and sarcomas, and 40% had miscellaneous cancers.
In addition, 43 of the patients had taken or were taking cancer drug therapies, whereas the remaining 36 were naive to these treatments. In the therapy group, the majority were treated with tyrosine-kinase inhibitors (24%) or anthracyclines (23%).
The cancer patients, as well as 20 healthy controls (45% women; mean age 56 years), underwent conventional 2D echo imaging to measure LVEF. In addition, speckle-tracking echo was used to measure global circumferential strain (GCS) and global radial strain (GRS). Same-day troponin I and brain natriuretic peptide (BNP) tests were also conducted.
The researchers found that the treated and untreated patients had similarly reduced GCS (-23 vs -23, respectively) and GRS (30 vs 34.1). And all of these rates were significantly lower than those found in the healthy-controls group (P<0.05 for all comparisons).
Only 17% of the patients with cancer showed a loss of torsion and/or fibrosis, and only two patients showed an increase in troponin I. Although BNP >50 pg/mL was found in 39% of the patients, there were no correlations between this measure and strain values.
Prognostic Parameters Needed
Khattar reported that the researchers had hypothesized that patients with cancer who had not started treatment would have normal strain values. So finding that they had reduced values that weren"t significantly different from those who received treated was a surprise. "It raises the question of whether the cancer disease process itself has some adverse effect," he said. "We can surmise that there are some inflammatory components to the tumor growth that affect the heart muscle, but more research is needed."
He pointed out that the current study has several limitations, including the heterogeneity of the patient population and the fact that the patients were relatively healthy since those with LV dysfunction were excluded and that the study was clinically driven.
"Frankly, I think we need to look at these issues more specifically. What we did was purely observational; it needs to be looked at in a more systematic way," said Khattar. He added that a study is needed that begins with echocardiographs in cancer patients before they start any kind of treatment and then follows them throughout therapy to see what happens to both strain and biomarkers.
"This might help us to work out which of these parameters have any kind of prognostic significance."