CARDIOVASCULAR JOURNAL OF AFRICA • Volume 33, No 3, May/June 2022 AFRICA 109 Methods We performed a retrospective analysis of 45 consecutive patients with severe symptomatic calcific aortic stenosis who underwent TAVI at Siyami Ersek Hospital from 2013 to 2015. Pre-procedural coronary angiography was performed to assess the need for revascularisation. Pre-TAVI assessment was initially done with transthoracic echocardiography, followed by an electrocardiography-gated, multi-slice CT study. Severe aortic stenosis was defined as: peak transvalvular gradient of ≥ 40 mmHg on transthoracic echocardiography or transoesophageal echocardiography or dobutamine stress echocardiography (DSE), and an aortic valve area ≤ 1.0 cm2. Each case was considered by a multidisciplinary cardiovascular team. The patient was accepted for TAVI if he/she was deemed unable to undergo open-heart surgery due to excessive risk [Society of Thoracic Surgeons (STS) score ≥ 10 or logistic EuroSCORE ≥ 20] or was unsuitable for surgical aortic valve replacement because of medical co-morbidities or because of technical considerations (for example if the patient had a calcified aorta or scarring from previous cardiac surgery). TAVI was performed under general anaesthetic, or under local anaesthetic with sedation. The procedure was performed via the transfemoral approach. A temporary pacemaker was placed in the right ventricular apex, and a balloon valvuloplasty was performed under rapid ventricular pacing, followed by implantation of the valve. Electrocardiographic and echocardiographic parameters after TAVI were recorded. The study protocol conforms to the ethical guidelines of the 1975 Declaration of Helsinki as reflected in a priori approval by our institution’s human research committee. All CT examinations were performed with a 64-slice CT scanner (Toshiba Aquilion 64, Otawara, Japan). Image acquisition occurred using a detector collimation of 64 × 0.5 mm, tube current of 120 kVp and rotation time of 400 msn. Scanning time varied between 5.7 and 8.4 seconds. Retrospective ECG gating was used for data reconstruction. Image reconstructions were performed at 70–80% RR intervals. An intravenous dose of 100 ml non-ionic contrast agent Iopromide (Schering AG, Berlin, Germany) was administered at an infusion rate of 4 ml/s, followed by 30 ml saline infusion. Post-processing was performed on an Aquarius workstation (TeraRecon, Inc). All images were read by two experienced physicians. Intra- and inter-observer reproducibility for quantification of epicardial fat was greater than 0.95. Epicardial fat was defined as the adipose tissue between the epicardium and the visceral pericardium. Epicardial fat tissue was identified with voxels between –30 and –190 Hounsfield units. Measurement was performed at the basal level of the short-axis images. Three measurements were performed at the superior, mid and inferior levels (75, 50 and 25% level of full length, respectively) of the right ventricle. The average of three separate measurements was used for the analysis10 (Fig. 1). Statistical analysis Statistical analyses were performed with NCSS (Number Cruncher statistical system) 2007 (NCSS, LLC Kaysville, Utah, USA). Data were analysed using descriptive statistical methods (mean, standard deviation, median, frequency and rate). The Kruskal–Wallis test was used for the comparison of normally distributed variables and two-group assessment was done with the Mann–Whitney U-test. Comparison of numerical data for before and after measurements was performed with the pairedsamples test. The McNemar test was used for comparison of qualitative data. A p-value of < 0.05 was considered statistically significant. A 95% confidence interval reflected a significance level of 0.05. Results The patient demographics and clinical characteristics are shown in Table 1. A total of 45 patients, including 37.8% (n = 17) male and 62.2% (n = 28) female were included in the study. The mean age of the study population was 79.07 ± 6.18 years (age range 60–89). Baseline laboratory data characteristics are shown in Table 2. Two patients died during the procedure prior to valve implantation (4.4%). The overall in-hospital mortality rate was 11.4% (five patients). Pre-procedural echocardiographic and CT data are shown in Table 3. The mean valve area was 0.78 ± 0.15 cm2. The mean STS score was 5.15 ± 3.54, and the mean logistic EuroSCORE was 11.91 ± 9.14. Seven patients (18.9%) underwent permanent pacemaker implantation after the TAVI procedure, mostly due to high-degree atrioventricular block. The rate of stroke was 9.3% (four patients). Twelve patients (27.3%) had minor vascular complications, according to the VARC definition.11 The average thickness of epicardial fat was 13.06 ± 3.29 mm. We did not find a significant correlation between epicardial fat thickness and post-procedural left bundle branch block (LBBB), right bundle branch block (RBBB), paravalvular aortic regurgitation and pacemaker implantation rates (p > 0.05) (Tables 4, 5). Fig. 1. Epicardial fat and pericardium appearance on computed tomography.
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