RESULTS
Baseline characteristics. A total of 73 patients (mean age 63.19±9.64, 68.5% male) undergoing left heart catheterization comprised the study population. All patients were divided into two groups by their invasive LV pre-A pressure value. >12 mmHg group (43 patients;58.9%; LV pre-A pressure=17.2±3.05) was defined as elevated LAP group, ≤12mmHg group (30 patients,41.1%; LV pre-A pressure=7.5±2.19) was defined as normal LAP group. Demographic, clinical characteristics, laboratory results, medication use, and TTE results were compared between groups (Table 1). There were no differences in age, gender, medication use, and co-morbidities. Laboratory results (obtained within 24 hrs. prior to LV catheterization), including Hemoglobin, Platelet, ALT, and AST, were also similar between groups. In addition, baseline SBP and SBP during catheterization were not different between groups.
Echocardiographic Measurements. Even though E (E; 0.71±0.19 vs. 0.62±0.11, p=0.0093) and E/A ratio (E/A; 0.95±0.32 vs. 0.73±0.16,p=0.0002) were significantly higher in patients with elevated LAP group, there were no differences in E/e’ ratio and A value between groups. The TR jet velocity was able to measure in 50 patients of 73 patients and significantly higher in the elevated LAP group (TR velocity; 2.75±0.48 vs. 2.28±054, p=0.004). However, LAVi was similar between groups.
Lv global longitudinal strain . LV longitudinal strain was performed in all patients within 24 hrs. Prior LV catheterization was significantly impaired in patients with elevated LAP group (LV strain; -15.4±2.83 vs. -18.9±2.14, p<0.0001). Intra-observer (ICC 0.97, CI 95%:0.91-0.99) and inter-observer (ICC 0.94, CI95%:0.78-0.98) agreement of strain measurements were excellent.
Univariate and Multivariate Predictors of Elevated LV Filling Pressure: Echocardiographic parameters using the algorithm by 2016 ASE/EACVI guideline and LV GLS were entered the univariate and multivariate logistic regression model to find independent predictors of elevated LV filling pressure. In univariate modeling (Table 2), higher level of E/e’ (OR:1.32;95%CI:1.12-1.55, p<0.0001) and TR jet velocity (OR:1.20;95%CI:1.04-1.37, p=0.002) were highly associated with elevated LV filling pressure. In addition, LV GLS (OR:1.67;95%CI:1.31-2.14, p<0.0001) was univariate predictors of the elevated LAP.
TR jet velocity, E/e’, and LV GLS were entered into multivariate analysis (Table 2). After adjusting for E/e’ and TR jet velocity, LV GLS (OR:1.76;95%CI:1.14-2.71, p=0.0015) was found as an independent predictor of elevated LAP. Furthermore, after adjusting for LV GLS and E/e’, TR jet velocity (OR:1.25;95%CI:1.01-1.55, p=0.01) was found as an independent predictor for elevated LV filling pressure as well as E/e’ (OR:1.45;95%CI:1.07-1.95, p=0.0015) was found an independent predictor of elevated LAP pressure after adjusting for LV GLS and TR jet velocity.
Roc Analysis: Estimated LAP was determined using the algorithm recommended by the 2016 ASE/EACVI guideline. In 9(12.3%) patients of 73 defined as indeterminate based on the algorithm. Of those, 6 patients had elevated Pre-A pressure, and 3 patients had normal pre-A pressure. According to the algorithm, 29 (39.7%) patients were defined as elevated LAP, and 35 (48%) patients were defined as normal LAP. ROC analysis based on the logistic regression model was used to analyze the accuracy of the algorithm to predict the elevated LAP. Also, the individual effect of parameters using the algorithm were analyzed. AUC of LAVi was lower (AUC:0.61, specificity 73.40%, sensitivity 65%) to estimate elevated LAP compared with TR velocity (AUC:0.77, specificity 81%, sensitivity 75.80%), and E/e’(AUC:0.75, specificity 87%, sensitivity 65%) (figure1, Table3). Furthermore, LV GLS had a higher AUC with higher sensitivity (AUC=0.83, specificity73.4%, sensitivity 86%) to estimate elevated LAP compared to echocardiographic parameters using the algorithm. LV longitudinal strain cut-off value was found - 18.1% based on the ROC curve, and > -18.1% of GLS was defined as elevated LAP. GLS -18.1% had higher sensitivity to predict LAP (AUC:0.79, specificity 73%, sensitivity 84%) compared with the algorithm (AUC:0.76, specificity 77%, sensitivity 72%) (figure2).
Correlation Analysis:  Pearson correlation method was used to assess the correlation between pre-A pressure and echo parameters (Table4). There was no correlation between pre-A and E (r=0.18), A (-0.07), and LAVi(r=0.19). There was also a weak correlation between invasive Pre-A pressure, E/A(r=0.27), E/e’(r=0.36), and TR velocity (r=0.36). However, there was a moderate correlation between LV GLS (r=0.47) and invasive pre-A pressure. On the other hand, there was not a good correlation between LV GLS and diastolic echo parameters. E/e’(r=0.34) LAVi (r=0.04) and TR velocity (r=0.11) (figure3).