Cardiac Monitoring Guidelines in Clinical Trials and Post-Approval Surveillance for Patients Exposed to Anticancer Treatments: Do the Data Support the Recommendations?

Concerns regarding cardiac adverse events during and after cancer care include contractile dysfunction, dysrhythmia, and inflammation. Clinical trials and practice guidelines may require or recommend sequential ejection fraction determinations for early recognition of contractile dysfunction, bio-marker screening where inflammation or contractile dysfunction could be anticipated, and multiple electrocardiograms with timings of cardiac intervals. In some instances, surveillance schedules used in clinical trial protocols have been incorporated in recommendations without revision or critical scrutiny. When adverse events are rare and interpretative parameters imperfect, false positive results may lead to delay or interruption of vital cancer treatment, may suggest that further cardiac testing be undertaken, and may add to patient anxiety. The risks of excessive monitoring also include inconvenience and increased cost. This paper looks at areas where surveillance recommendations may be problematic, specifically, ejection fractions, cardiac biomarkers, and electrocardiographic monitoring are considered. Changes reported following surveillance monitoring of cancer patients using these parameters may reflect true adverse events or clinically relevant future risk, but interpretative uncertainty or true physiologic change that is unrelated to the drug in question should be considered. Clinicians may not be sufficiently aware of the degree to which reported changes may reflect surveillance artifacts. A balance that incorporates both the likelihood of an event that could be prevented along with clinical implications is suggested. The authors recognize that differentiating among these variables is not always possible yet advocate for modifying surveillance schedules to balance the frequency and severity of events that can be mitigated, based on reliable data.