CARDIOVASCULAR JOURNAL OF AFRICA • Volume 34, No 1, January–April 2023 AFRICA 13 In our study there was a moderate correlation between LVEDVTTE and LVEDVCMR (r = 0.57, p = 0.01) and LVESVTTE and LVESVCMR (r = 0.47, p = 0.01). On the other hand, among the 19 patients who had the right ventricle measured by PISA during TTE, RVolTTE (53.3 ± 21.6 ml) and RVolCMR (29.7 ± 17.1 ml) were significantly different (p = 0.002) and not correlated (r = 0.04, p = 0.8). None of the TTE quantification parameters were correlated to RVolCMR (Table 4). Concerning LV remodelling, 15 patients (30%) with no severe LV dilatation according to TTE thresholds (≤ 70 mm) had severe LV dilatation according to CMR thresholds (> 246 ml). Two patients (4%) had severe LV dilatation by TTE (> 70 mm) and no severe dilatation by CMR (≤ 246 ml). Quantification of LV dilatation was concordant for 33 (66%) patients, with 29 (58%) with non-dilated left ventricles and four (8%) with dilated left ventricles (Table 5). Discussion This study highlights the following findings: • For half of the patients who had both CMR and TTE in the clinical management of AR, there were difficulties in quantifying AR, either because of lack of multiparametric analysis (only one method possible) or because of discrepancies in the different methods. In those patients, CMR finally detected seven (14%) patients with mild AR, 11 (22%) with moderate AR and seven (14%) with severe AR. • In 25 patients (50%) who had a quantification by TEE, AR was re-graded by CMR in 18 (36%) patients. • Quantification of LV dilatation was concordant by both methods in only 33 (66%) patients. • LV volumes were greater with CMR than TTE, with a moderate correlation. RVolCMR and RVolTTE were not correlated. Contemporary guidelines recommend CMR in patients with significant disease and suboptimal TTE images.2 In our cohort, in half of the cases, difficulties prevented an objective quantification of AR using the usual TTE parameters. In inconclusive TTE cases, 20 (40%) patients had no multiparametric analysis. For five (10%) patients, there was a disagreement between TTE parameters. This can be explained by the following reasons. The PISA method, which is recommended by the current guidelines, is based on a fluid dynamic concept and uses hemispheric assumptions of flow convergence region.16-18 However, the 2D PISA method is inherently limited because of the geometric assumptions of PISA shape that are necessary to calculate regurgitant volume. The pressure half-time depends on systemic vascular resistance and LV compliance.19 The concept of vena contracta is indeed based on the assumption that the regurgitant orifice is almost circular. The orifice is however often elliptical or irregular, which changes the width of the vena contracta in different views. Furthermore, intermediate vena contracta values (3–6 mm) need confirmation by a more quantitative method, when feasible.3 In our study, 36% of patients had intermediate vena contracta values. Considering the excellent reproducibility of AR grading by CMR20 in prospectively recruited patients,21,22 our findings provide further support for the contemporary recommendation to proceed with CMR in cases of suboptimal TTE assessment.2 RVolCMR and RVolTTE were not correlated in our study. These results contrasted with those of Choi et al.,19 who found a weak correlation for eccentric jets. These variations can be explained by differences in methodology. In our cohort, PISA was not assessed according to jet eccentricity and only 38% of patients were assessed by this method. Some authors have identified limitations of the PISA method. PISA is based on the assumption of hemispherical and homogenous flow convergence, which may not be present in vivo.23 Another pitfall includes timing of measurement. PISA Five patients with severe AR by CMR had aortic valvular replacement Medical therapy for 20 patients, including two patients with severe AR by CMR Aortic valvular replacement for seven patients: • Two patients with severe AR by TTE and CMR • One patient with moderate AR by TTE and severe by CMR • Two patients with mild AR by TTE and CMR, aortic bicuspid valve and ascending aortic diameter ≥ 50 mm • Two patients with severe AR by TTE and moderate by CMR, aortic bicuspid valve and ascending aortic diameter ≥ 50 mm Medical therapy for 18 patients 25 patients with inconclusive AR by TTF 25 patients with AR graded by TTE Fig. 5. Flow chart of the outcome of therapy. Table 4. Correlation coefficients between TTE and CMR parameters LVEDVCMR LVESVCMR RVolCMR LVEDVTTE 0.57* 0.48 0.33* LVESVTTE 0.42* 0.47* 0.24 LVEDDTTE 0.54* 0.53 0.39* LVESDTTE 0.44* 0.45* 0.27 RVolTTE 0.16 0.22 0.04 Vena contracta 0.04 0.05 0.06 PHT 0.05 0.16 0.16 EDVDA 0.11 0.13 0.22 TTE, transthoracic echocardiography; CMR, cardiovascular magnetic resonance imaging; LVEDV, left ventricular end-diastolic volume; LVESV, left ventricular end-systolic volume; LVEDD, left ventricular end-diastolic dimension; LVESD, left ventricular end-systolic dimension; RVol, regurgitant volume; EDVDA, enddiastolic velocity in the descending aorta; PHT, pressure half-time. *p < 0.05. Table 5. Comparison of LVEDVCMR and LVEDDTTE according to poor prognosis thresholds6,28 LVEDVCMR ≤ 24 6ml > 246 ml LVEDDTTE ≤ 70 mm 29 (58) 15 (30) > 70mm 2 (4) 4 (8) LVEDV, left ventricular end-diastolic volume; LVEDD, left ventricular enddiastolic diameter. p = 0.1.
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