An evaluation of the safety of continuing trastuzumab despite overt left ventricular dysfunction.

Background: The major limitation in the use of trastuzumab therapy is cardiotoxicity. We evaluated the safety of a strategy of continuing trastuzumab in patients with breast cancer despite mild, asymptomatic left ventricular impairment. Methods: Charts of consecutive patients referred to a cardio-oncology clinic from January 2015 to March 2017 for decline in left ventricular ejection fraction (lvef), defined as a fall of 10 percentage points or more, or a value of less than 50% during trastuzumab therapy, were reviewed. The primary outcome of interest was change in lvef, measured before and during trastuzumab exposure and up to 3 times after initiation of cardiac medications during a median of 9 months. Results: All 18 patients referred for decline in lvef chose to remain on trastuzumab and were included. All patients were treated with angiotensin converting-enzyme inhibitors or beta-blockers, or both. After initiation of cardiac medications, lvef increased over time by 4.6 percentage points (95% confidence interval: 1.9 percentage points to 7.4 percentage points), approaching baseline values. Of the 18 patients, 17 (94%) were asymptomatic at all future visits. No deaths occurred in the group. Conclusions: Many patients with mildly reduced lvef and minimal heart failure symptoms might be able to continue trastuzumab without further decline in lvef, adverse cardiac events, or death when treated under the supervision of a cardiologist with close follow-up.

Baroreflex variability and "resetting": a new perspective.

A new framework is proposed for the interpretation of spontaneous cardiac baroreflex sensitivity data and the general concept of baroreflex resetting. The framework is used to explore baroreflex function along two separate lines of inquiry: one following a direct intervention in baroreflex function in individual subjects, another in a group of subjects where baroreflex function may have been compromised by coronary artery disease or aging. It is found that under baseline conditions the baroreflex is in a "free-floating" state in which the gain or "sensitivity" is highly variable, while under orthostatic stress or in the absence of or reduced vagal input the gain is more tightly controlled with an expected decline in sensitivity but a very large decline in the variability of that sensitivity. It is concluded that baroreflex "resetting" is better viewed not simply as a change in baroreflex sensitivity but rather as a change in the "focus" or "attention" of the baroreflex as expressed by an observed decline in the variability of the measured gain. The results do not support the interpretation of baroreflex "resetting" as a departure from or return to a universal "set point" as in homeostasis or open loop models.