Statistical Analysis
We compared demographic, clinical, and laboratory data between the two
groups using t-tests for continuous variables and Fisher’s exact tests
for categorical variables. LA strain was divided into three
components—LA reservoir, conduit, and contractile—to determine the
association of each phase of atrial function with stroke subtypes.
Multivariable logistic regression analysis adjusting for covariates was
performed. The first model was adjusted for age and sex. The second
model was adjusted for covariates in model 1 plus systolic blood
pressure, history of congestive heart failure defined as heart failure
with mid-range and preserved ejection fraction according to the
guidelines from the Heart Failure Society of America25, and NIHSS. LA strain components (reservoir,
conduit, and contractile) were assessed both as linear and tertile
categorical variables to simplify the analysis for easier interpretation
and to study the trend within the LA strain dataset. All ESUS patients
were give a prescription of cardiac event monitor (CEM). Those with
negative CEM were given implantable loop recorders (ILR). The presence
of AF was defined as identification of AF for more than 30 seconds on
monitoring.
We compared three phases of LA strain between all ESUS patients with and
without AF detection using t-tests. The association between LA strain
and detection of AF was assessed using logistic regression analysis.
Sensitivity analyses were performed adjusting for age, focusing only on
ESUS patients who received cardiac monitoring, and focusing only on ESUS
patients found to have AF on cardiac monitoring to compare differences
in LA strain between those with an AF burden of less than 24 hours
versus greater than or equal to 24 hours. Analysis was performed using
STATA SE v17 with a p-value < 0.05 as statistically
significant.