Definition. What we seek to prevent (heart failure) can take years to develop, and when it does, it’s often too late to have a major impact on disease progression. For this reason we screen for “cancer treatment-related cardiac dysfunction” (CTRCD) but should recognize that this is not itself an illness, in the sense that many patients never develop heart failure.
Clinical prediction. In addition to the type of chemo- or radiotherapy, the major drivers are the risk factors for HF – age, CAD, other heart disease, hypertension, diabetes.
Ejection Fraction. This parameter is mentioned in all the guidelines, but it is used in surveillance in barely 50% of patients. There are several disadvantages – perhaps the biggest is that it’s quite variable in any case, so the threshold to discriminate change from background noise is rather large, so it is insensitive to minor change.
Other echocardiographic markers. Myocardial strain is a measurement of shortening with each contraction. It’s a robust parameter and a relative change of 10-15% is meaningful. The current Australian-led SUCCOUR trial indicates that strain surveillance led more patients to be prescribed cardioprotection and therefore fewer to develop a meaningful reduction of EF in follow-up.
CMR markers. CMR has the capacity to characterize myocardial tissue – expansion of the extracellular matrix, oedema and scarring. There is a hope that this would be more useful than functional change, but these parameters are quite variable, so the specificity of this signal seems limited.
Biomarkers. Both troponin and natriuretic peptides have been used. High-sensitivity troponin is very sensitive to minor injury, so specificity is a problem. BNP is probably insufficiently sensitive.
Conclusion. Although the guidelines are very focused on EF, the best parameter for early detection is probably myocardial strain.