SP-13786 br International Journal of Radiation Oncology

International Journal of Radiation Oncology Biology Physics
Table 3 Results of echocardiography after a median follow-
Table 4 Model characteristics of the final model for the
up time of 7 years
endpoint global longitudinal systolic strain of the left ventricle
in breast cancer survivors within first 10 years after radiation
At time of
therapy
Variable echocardiography %
Variable B SE 95% CI for B P value*
Left ventricular ejection fraction
with BC*
Abbreviations: B Z regression coefficient; CI Z confidence inter-
val; Dmax Z maximum dose; LMCA Z left main coronary artery;
SE Z standard error.
Results are based on 52 breast cancer survivors.
Abnormal left ventricular
* P value between the variable and the endpoint global longitudinal
ejection fractiony
strain of the left ventricle, calculated using linear regression analysis.
Left ventricle global longitudinal
mechanisms of radiation-associated cardiac damage remain
to be determined.
Mean
We found an association between clinical variables and
diastolic function. Our results showed that age and hyper-
Missing because of limited 57 52.3
tension at time of BC diagnosis were selected most for the
quality
endpoint diastolic function in the 1000 bootstrap samples.
Left ventricle diastolic function
This outcome is consistent with previous studies, which
have also shown no significant increased risk of LV dia-
patients with BCx
stolic dysfunction after BC treatment.9,23,37
A limitation of our study is its cross-sectional design.
We did not have echocardiography data before RT, and
Abnormal left ventricle diastolic
therefore we are not able to report on possible changes after
functionk
RT. However, the relationship found for systolic (GLS)
function suggests that RT might play a role in the etiology
of these effects. The decline in cardiac function in relation
to the dose of SP-13786 is subtle. This subtlety makes it
difficult to identify differences between patient groups and
Abbreviation: BC Z breast cancer.
* Measured left ventricular ejection fraction with biplane method of
control groups. By using dose-effect relationships, we are
disks summation (modified Simpson’s rule), if not available with
able to identify small changes that cannot be found just by
eyeballing.
comparing irradiated and nonirradiated populations.
y Defined as a left ventricular ejection fraction <54% according to the European Association of Cardiovascular Imaging/American Soci- It was also possible to consider patient age and follow-
up time, although in our analysis age was not associated
ety of Echocardiography.
z Measured using automated 2-dimensional speckle-tracking. with the decline in systolic cardiac function but was asso-
x Average of the mean e’ septal and e’ lateral. ciated with a decline in diastolic function. Follow-up time
k Defined as e’ lateral or e’ septal 2.5% below the normal range for was not associated with systolic or diastolic function.
each age group, according to the European Association of Echocar-
Moreover, it is important to note that we performed
diography/American Society of Echocardiography. In this cohort, the
explorative analysis in this study. Therefore, prospective
BACCARAT prospective cohort study or the MEDIRAD
EARLY HEART study.8,38 The results of the current study
of the coronary arteries in the pathogenesis of radiation- should therefore be considered as hypothesis generating,
induced cardiac toxicity. not for making definitive conclusions. Further research and
It could be hypothesized that irradiation of coronary validation in other and larger cohorts is needed to confirm
arteries may initiate inflammation, coronary spasms, or our results.
rupture of an existing atherosclerotic plaque, resulting in Another limitation is that it remains to be determined if,
insufficient supply of oxygenated blood to the myocardium. in this specific group of patients, subclinical effects will
This can eventually lead to secondary damage to the eventually translate into major cardiac events. However, as
myocardium, in addition to direct radiation-induced local shown in the general population, GLS provides independent
damage to the microvascular endothelial cells, leading to and additional prognostic information regarding long-term
microvascular rarefaction and myocardial inflammation, risk of cardiovascular morbidity and mortality.29
Volume 104 Number 2 2019 Cardiac function after breast irradiation 399