RESULTS
TEE evaluation of function during diastole was inconsistently completed,
but consistency increased over the course of the study, approaching 90%
of eligible patients by the end of the study. Relative frequency of
reasons for incomplete evaluation (eg. poor image alignment, excessive
nonechocardiographic/clinical demands) could not be determined. Data
were captured on 176 eligible subjects (mean age 65.2 +/- 9.2 years,
73% male, 76% white). Baseline characteristics of study participants,
with normal (N=105) vs abnormal (N=71) baseline performance during
diastole, are shown in Table 1 . Those with abnormal
echocardiographic parameters during nonsystole: 1) were older; 2) were
more likely to be female, and/or have a history of congestive heart
failure, valvular disease, and/or renal dysfunction; 3) trended toward a
higher prevalence of prior myocardial infarction and history of chronic
lung disease; 4) less likely to have hypertension; 5) trended towards a
shorter duration of CPB. Overall, baseline characteristics suggested a
greater burden of comorbidity at baseline for those with diastolic
dysfunction, supported by significantly higher baseline ASA class, a
composite comorbidity score well recognized to be associated with
postoperative morbidity and mortality
[18-20]. Based on the log-likelihood
test and BIC, LCA classified subjects into two groups (high and low
severity) based on baseline characteristics, and the burden of comorbid
illness appeared to be greater in latent class 2 than 1 (Table
1 ). Subjects with diastolic dysfunction were more likely to be
classified in latent class 2 than 1 (Table 1 ).
Median time to hospital discharge was significantly longer for subjects
with abnormal vs normal performance during diastole (abnormal: 9.1/IQR
6.6-13.5 days; normal: 6.5/IQR 5.3-9.7 days) (P<0.001 by
Kruskal-Wallace test). Probability of hospital discharge on any given
postoperative day (hereafter referred to as “daily probability of
discharge”) was significantly lower for those with diastolic
dysfunction (Fig 1 ).There was a dose-response relationship
between severity of diastolic dysfunction and daily probability of
discharge - those having the most severely abnormal performance had the
lowest daily probability of discharge (Fig 2 ).
We examined the independent relationship of baseline diastolic
dysfunction to daily probability of discharge in a series of unadjusted
and adjusted Cox-Proportional Hazards models (Table 2 ) Daily
probability of discharge was 46% lower (RR 0.54/95% CI 0.40-0.75) for
those with diastolic dysfunction compared to those with normal
performance during diastole in unadjusted analysis. Adjusting for age,
sex (Table 2, Model 1 ), duration of CPB (Table 2,
Models 1, 2 ), severity of illness latent class (Table 2, Models
2, 3 ) history of heart failure and myocardial infarction (Table
2, Model 3 ), the daily probability of discharge remained significantly
lower for those with diastolic dysfunction. A Sensitivity Analysis
excluding 5 subjects with more than mild valvular disease (eg. MAC,
Aortic disease, Mitral disease) did not affect these results (RR
0.63/95% CI 0.45-0.90). Our propensity analysis successfully matched 42
subjects with and without diastolic dysfunction, and showed that daily
probability of discharge was 37% lower (RR 0.63/95% CI 0.40-1.00) for
those with diastolic dysfunction. Our LCA showed the daily probability
of discharge: 1) was significantly lower for the group with both
diastolic dysfunction and high severity of illness latent class (RR
0.39/95% CI 0.26-0.58; P<0.001); 2) tended to be lower in the
group with diastolic dysfunction and low severity of illness (RR
0.72/95% CI 0.50-1.05; P=0.09); 3) had no pattern of relation for the
two strata with normal performance during diastole
(Supplemental Fig 1 ). Finally, in additional models
that included LV performance during diastole, E and the E/e’ ratio as
covariates in the regression model (Table 2, Model 3 ), the
association between abnormal e’ and discharge was unchanged (RR 0.61/
95% CI 0.42-0.88). Abnormal E was also independently associated with
discharge (RR 0.61/ 95%CI0.39-0.94), but E/e’ was not (RR 0.85/95% CI
0.48-1.52).
There were no significant differences in intravenous fluid
administration (6169±2958 ml vs. 6229±3542 ml, P= 0.99) or transfusion
of packed red blood cells (229±404 ml vs. 187±377 ml; P=0.48) between
subjects with and without diastolic dysfunction. Secondary intermediate
outcomes are shown in Table 3 . Subjects with diastolic
dysfunction were more likely to be extubated >6 hours after
surgery, to require supplemental oxygen longer, and to be diagnosed with
the composite outcome of heart failure, respiratory
insufficiency/failure, or pulmonary edema. We found no significant
differences by performance during diastole in the incidences of
postoperative atrial fibrillation, AKI, stroke, or infection. A higher
proportion of subjects with diastolic dysfunction were readmitted to the
ICU; however, this difference was not statistically significant
(Table 3 ).
The relationship of diastolic dysfunction and secondary intermediate
outcomes to daily probability of discharge is shown in Table 4 .
Similar to baseline diastolic dysfunction, each of the secondary
outcomes was associated with a lower daily probability of discharge in
unadjusted analysis. In multivariable cox regression, secondary outcomes
had modest effect on the relationship between baseline diastolic
dysfunction and daily probability of discharge, which remained 37% less
likely for those with diastolic dysfunction (Table 4 ).