High-sensitivity cardiac troponin I-guided combination angiotensin receptor blockade and beta blocker therapy to prevent anthracycline cardiotoxicity: the Cardiac CARE RCT
Authors: Henriksen Peter , MacLean Morag , Atter Marek , Lewis Steff , Rodriguez Aryelly 
Published: September 2024

Background
Anthracycline-induced cardiotoxicity has a variable incidence, and the development of left ventricular dysfunction is preceded by rises in plasma cardiac troponin concentrations. Beta-adrenergic receptor blocker and renin-angiotensin-system inhibitor therapies have been associated with modest cardioprotective effects in unselected patients receiving anthracycline chemotherapy.

Methods
In a multicentre prospective randomised open-label blinded end-point trial, patients with breast cancer and non-Hodgkin lymphoma receiving anthracycline chemotherapy underwent plasma high-sensitivity cardiac troponin concentration monitoring and cardiac magnetic resonance imaging before and 6 months after anthracycline treatment. Randomised controlled trial – patients at high risk of cardiotoxicity (plasma cardiac troponin I concentrations in the upper tertile during chemotherapy) were randomised to standard care plus cardioprotection (combination carvedilol and candesartan therapy) or standard care alone. The primary end point was 6-month change in left ventricular ejection fraction. Prognostic cohort study – in low-risk non-randomised patients with plasma cardiac troponin I concentrations in the lower two tertiles, we hypothesised the absence of a 6-month change in left ventricular ejection fraction (± 2%).

Results
Between October 2017 and June 2021, 175 patients (mean age 53 years; 87% female; 71% breast cancer) were recruited. Patients randomised to cardioprotection (n = 29) or standard care (n = 28) had mean left ventricular ejection fractions of 65.7 ± 6.6% and 64.9 ± 5.9%, respectively, at 6 months. Twenty patients (68.9%) were adherent to cardioprotection therapy at 6 months. Adverse events were more commonly reported in the cardioprotection group, with 71.4% of patients having at least one adverse event compared with 12.7% non-randomised and 10.3% standard care patients. After adjusting for age, pre-treatment left ventricular ejection fraction and planned anthracycline dose, the estimated mean percentage-point difference in 6-month left ventricular ejection fraction between the cardioprotection and standard care groups was –0.4% (95% confidence interval –3.59 to 2.85%; p = 0.82). In low-risk non-randomised patients, baseline and 6-month left ventricular ejection fractions were 69.3 ± 5.7% and 66.4 ± 6.3%, respectively (estimated mean difference 2.9%, 95% confidence interval 1.45 to 4.28%; p = 0.92, not equivalent). The main secondary objective of demonstrating zero percentage-point change with equivalence of ± 2% was not met.

Conclusions
Combination candesartan and carvedilol therapy had no demonstrable cardioprotective effect in patients receiving anthracycline-based chemotherapy with high-risk on-treatment plasma cardiac troponin I concentrations. Low-risk non-randomised patients had similar modest declines in left ventricular ejection fraction, suggesting that the clinical utility of routine cardiac troponin monitoring remains undefined. The modest short-term declines in left ventricular ejection fraction suggest that early cardioprotection therapy has a limited role in patients receiving anthracycline-based chemotherapy.

Limitations
Treatment effect might have been influenced by several patients stopping cardioprotection treatment within 2 months of randomisation. Across all groups, reduction in left ventricular ejection fraction was lower than expected and patients with high-risk cardiac troponin I concentrations did not exhibit a greater fall in left ventricular ejection fraction than low-risk patients. These factors, together with the trial being powered to detect a 5-percentage-point change in left ventricular ejection fraction, mean that a small treatment effect was not excluded.

Future work
Future work should aim to understand the transition from small changes in cardiac function, 6 months after completion of anthracycline chemotherapy, to the late development of heart failure in this population.

Trial registration
This trial is registered as ISRCTN24439460 and EudraCT 2017-000896-99.

Funding
This award was funded by the National Institute for Health and Care Research (NIHR) Efficacy and Mechanism Evaluation (EME) programme (NIHR award ref: 15/48/20) and is published in full in Efficacy and Mechanism Evaluation; Vol. 11, No. 12. See the NIHR Funding and Awards website for further award information.