Large Discrepancy
The “large discrepancy in the rate of injury” with cTnT “has implications for the clinical interpretation of cardiac biomarkers in routine practice, and we should proceed with caution,” Dr. Austin told this news organization.
The finding has implications because guidelines don’t currently differentiate based on the type of troponin, Dr. Austin said in a press release. “I was surprised by the difference, and I think this raises the question of what troponin we should be using.”
Secondary outcomes focused on cardiac function, measured using echocardiography and included left ventricular global longitudinal strain (LVGLS) and left ventricular ejection fraction (LVEF). These were measured at baseline, 4 weeks after the last anthracycline dose and 1 year after the final chemotherapy.
There was no between-group difference in LVGLS cardiac function (21% for enalapril vs 22% for standard of care; adjusted OR, 0.95; 95% CI, 0.33-2.74; P = .921). This was also true for LVEF (4% for enalapril vs 0% for standard of care group; adjusted OR, 4.89; 95% CI, 0.40-674.62; P = .236).
Asked what the research team plans to do next, Dr. Austin said “the immediate first step” is to continue following PROACT patients. “We know heart failure events and cardiac dysfunction can occur later down the line.”
Due to the challenge of enrolling patients into trials like PROACT, “we should come together as a sort of a broader cardiovascular/oncology academic community to try to understand how we can better recruit patients into these studies,” said Dr. Austin.
“We need to solve that problem before we then go on to maybe examine other potential preventative therapies.”
He doesn’t think an alternative ACE inhibitor would prove beneficial. “We need to look elsewhere for effective therapies in this area.”
He noted these new findings are “broadly consistent” with other trials that investigated angiotensin receptor blockers.
Tough Population
Commenting on the study during a media briefing, Anita Deswal, chair, medicine, Department of Cardiology, Division of Internal Medicine, The University of Texas, commended the researchers for managing to enroll patients with cancer as this is “a tough” population to get to agree to being in a clinical trial.
“These patients are often overwhelmed financially, physically, and emotionally with the cancer diagnosis, as well as the cancer therapy and, therefore, to enroll them in something to prevent, maybe, some potential cardiac toxicity down the line, is really hard.”
Past trials investigating neuro-hormonal blockers to prevent cardiotoxicity have been criticized for enrolling patients at “too low risk,” said Dr. Deswal. “But investigators here went that step beyond and enrolled patients who were going to receive higher doses of anthracyclines, so kudos to that.”
And she noted investigators managed to get patients on almost the maximum dose of enalapril. “So, the drug was poised to have an effect — if it was there.”
The negative results may have something to do with endpoints. “Maybe we haven’t quite figured out what are the cutoffs for high sensitivity troponin I that identify patients truly at risk” of developing heart failure in the future.
Commenting on the study for this news organization, Anu Lala, MD, assistant professor of medicine at the Icahn School of Medicine at Mount Sinai, New York City, said the results may come as a surprise to some.
“ACE inhibitors are considered cardioprotective and for this reason are often used prophylactically in patients receiving chemotherapy.”
Dr. Lala agrees troponin may not be the right endpoint. “Another question is whether clinical outcomes should be followed in addition to symptoms or onset of any heart failure symptoms, which may hold greater prognostic significance.”
The study was funded by the National Institute for Health and Care Research.
A version of this article appeared on Medscape.com.