High blood levels of troponin I protein can identify patients at highest risk for heart damage after chemotherapy, according to a report in the May 18th rapid access issue of Circulation. The report suggests that tracking blood levels can help doctors form a prevention plan for some chemotherapy patients.

“Damage to the heart is one of the most worrisome long-term side effects of high-dose chemotherapy,” said lead author Daniela Cardinale, M.D. “Therefore, it is important to identify biochemical markers that might indicate which patients are at greatest risk and how severe their heart disease might be.”

In the current study, researchers took blood samples from 703 adult cancer patients to measure troponin I levels after high-dose chemotherapy and one month later. Values higher than 0.08 ng/mL were considered positive, while lower values were considered negative. Investigators found that 145 patients (21 percent) were troponin I positive immediately after chemotherapy and 63 patients (9 percent) were positive both immediately after chemotherapy and one month later.

The researchers found no significant reduction in cardiac function at the three-year follow-up of patients who had been troponin negative. These patients had only a 1 percent incidence of cardiac events such as myocardial infarctions. In contrast, the cardiac event incidence was 37 percent among patients who had been troponin positive immediately after chemotherapy and 84 percent among those who remained positive a month later.

Cardinale said, “Our study is the first to clearly show, in an adult population, that the risk of cardiac events in cancer patients can be predicted by evaluating the TNI (troponin I) release pattern after chemotherapy. Evaluating TNI values after chemotherapy is an easy, non-invasive, low-cost method that allows us to categorize the risk of cardiac events in cancer patients in the three years following chemotherapy.”

The study findings have several implications for oncologists and cardiologists who treat cancer patients. First, troponin level appears to classify level of cardiac risk early, before functional impairment becomes apparent. Thus, preventive treatments during this period may prevent or decrease the intensity of long-term adverse effects. In addition, it may be possible to use troponin I level as a marker of the safety and effectiveness of different chemotherapy treatments and newly developed cardiac protective treatments.