We reviewed echocardiography reports, including digitized cine-loop images, and clinical charts on 713 patients with nonvalvular AF who underwent TEE between 2012 and 2018 in Osaka Medical College Hospital. TEE was performed in order to screen intracardiac thrombosis prior to pulmonary vein isolation procedure and/or direct cardioversion. There were 493 men and 220 women with a mean age of 67 years. Patients with rheumatic/degenerative mitral valve disease, congenital heart disease, and those in whom echocardiography and/or laboratory data considered to be important for the current analysis, particularly the B-type natriuretic peptide (BNP) and left ventricular (LV) ejection fraction, were lacking were excluded.
Figure 1 shows percentages of the presence of LASEC classified by CHADS2 and CHA2DS2-VASc scores in the 713 patients. Overall, the incidence of LASEC was found to increase accordingly with increases in CHADS2 and CHA2DS2-VASc scores (P <0.001 for both). In the present study, following results were all drawn separately for the 2 groups: 349 patients with a CHADS2 score <2 (CHADS2 group); and 221 with a CHA2DS2-VASc score <2 (CHA2DS2-VASc group).
This study was approved by the Ethics Committee of Osaka Medical College with notification for guaranteed withdrawal of participants on the website providing means of “opt-out” (No. 2194-01).
Ultrasound machines used were Vivid 7 Dimension and Vivid E9 with the phased array probes for both transthoracic echocardiography and TEE (GE-Vingmed, Horten, Norway). LA diameter, and LV dimensions and wall thickness were measured under 2-dimensional image guidance. LV ejection fraction was obtained with the modified Simpson’s rule in the 2- and 4-chamber views, and an ejection fraction <50% was defined as LV systolic dysfunction. LV mass was calculated using the Devereux formula, indexed by the body surface area to draw LV mass index. LV mass index ≥115 g/m2 in men and ≥95 g/m2 in women were considered as the presence of LV hypertrophy . The severity of mitral regurgitation was determined semi-quantitatively using color-flow mapping.
Standard multiplane TEE was performed using the same ultrasound machines with 6Tc and 6VT-D probes, respectively. The entire LA cavity was thoroughly examined for LASEC and LA thrombus with the gain setting being adjusted for optimal analysis. Attention was paid to differentiate the LAA thrombus from pectinate muscles . TEE images, on a routine basis, were stored as cine-loops for the subsequent analysis. The severity of LASEC was categorized as being absent, mild or severe on the basis of the system described by Daniel et al. and Beppu et al. [19, 20]. Mild LASEC was defined as being present if dynamic echoes were seen only with high gain, whereas severe LASEC was present if spontaneous contrast was noted even with low gain.
To evaluate reproducibility of LASEC severity, 30 cases that were randomly selected from our population, including severe (n = 4), mild (n = 12), and none (n = 14), were analyzed by 2 independent experienced observers. The concordance rate (κ) for the corresponding LASEC severity was 0.93.
LAA velocity was also obtained with the pulsed Doppler sample volume 1 to 2 cm positioned inside the LAA orifice, averaged over 3 and 5 consecutive cardiac cycles in case of patients in sinus rhythm and of those in AF, respectively.
Thromboembolic risk scores
CHADS2 score was calculated by giving 1 point each for congestive heart failure, hypertension, age ≥75 years, and diabetes, and 2 points for prior stroke or transient ischemic attack , and patients with a CHADS2 score <2 were classified into the “low risk” category (CHADS2 group) [9, 22]. CHA2DS2-VASc score was calculated by giving 1 point each for congestive heart failure or LV systolic dysfunction (ejection fraction <40%), hypertension, diabetes, vascular disease, age 65 to 74 years, and female gender, and 2 points for prior stroke or transient ischemic attack and for age ≥75 years , and patients with a CHA2DS2-VASc score <2 were classified as “low risk” (CHA2DS2-VASc group) [9, 22].
Besides, we calculated HAS-BLED score (Hypertension, Abnormal Renal/Liver Function, Stroke, Bleeding History or Predisposition, Labile International Normalized Ratio [INR], Elderly, and Drugs/Alcohol) to assess the coagulation/bleeding status of the patients . We gave 0 point of “Labile INR” to all patients who had been taking DOACs.
Abnormalities of some clinical and echocardiographic parameters were determined as follows. Based on K/DOQI clinical practice guidelines , renal dysfunction was defined as an estimated glomerular filtration rate (eGFR) <60 mL/min/1.73m2. BNP ≥200 pg/mL was considered clinically significant in accordance with the statement guideline by the Japanese Heart Failure Society (www.asas.or.jp/jhfs/english/outline/guidelines_20180822.html). LA enlargement and LAA dysfunction were defined as LA diameter ≥50 mm and LAA velocity <20 cm/s, respectively [2, 25].
Continuous variables were expressed as mean ± SD and categorical variables as percentages. Comparisons of categorical variables were performed using the chi-square test or Fisher’s exact test as appropriate. Univariate and multivariate logistic regression analyses were introduced to predict determinants of LASEC for both CHADS2 and CHA2DS2-VASc groups. All analyses were performed using JMP Pro ver. 14.0 (SAS Institute, Cary, NC). A P values <0.05 was considered significant.