Objectives: This study aimed to evaluate the prognosis of patients with severe aortic stenosis at high surgical risk having low transvalvular mean pressure gradient and low flow versus high gradient treated with transcatheter aortic valve replacement(TAVR).
Background:Aortic stenosis is the most frequent valvular disease. Patients with low flow low gradient aortic stenosis (LFLG-AS) are characterized by higher cardiovascular risk and more comorbidities than the most frequent high gradient AS (HG-AS) patients are. Actually, few data exist on patients LFLG-AS undergoing TAVR.
Methods: in this retrospective, multi-centre study involving 345 patients, two groups were analysed following these criteria: the first group included patients with high gradient AS (HG-AS) with a mean transvalvular gradient ≥ 40 mmHg, the second group included the low flow low gradient patients (LFLG-AS) characterized by mean transvalvular gradient <40 mmHg, ejection fraction (EF) ≤ 50%, stroke volume index ≤ 35 ml/m2. During the statistical analysis, univariate and multivariate regression models were used, considering variables such as age, gender, BMI and comorbidities at the baseline.
Results: a total of 86 patients with HG-AS or LFLG-AS were identified. The primary end point, all-cause mortality at 1 year, was different in the two sub-groups but not significantly distinctive in the multivariate analysis, with death occurring in 3 (7,5%) versus 2 (4,3%) patients (OR: 1,6; 95% CI: 0.2-15.3; p=0,539), respectively. The change in the ejection fraction after TAVR was different in the two subgroups and of significant relevance: an increase of 5.9 ± 9.6 was seen in LFLG-AS compared to 0,1 ± 2,7 of ejection fraction increase in HG-AS (MD 6,3; 95% CI: 2.9-9,6; p=0,001 in multivariate analysis). Furthermore, we studied the variations in the mean transvalvular gradient pre and post- TAVR, finding in absolute values that there has been a major decrease of mean transvalvular gradient in HG-AS patients’ group: 35,9 ± 9,1 SD compared to 20,1 ± 5,4 SD of LFLG-AS group (MD 14.8; 95%CI: 11.0-18.6; p <0,001 in multivariate analysis). Also, we evaluated the presence of valvular regurgitation post-TAVR, statistically more frequent in LFLG-AS group 37,5% in contrast to 8,7% in HG-AS group (OR 16.2; 95% CI: 2.5-103.7; p=0,003 in multivariate analysis). Still we considered frequent adverse events post procedure as new onset of atrial fibrillation 25% in LFLG-AS and 10,9% in HG-AS group, pacemaker implantation in 12,5% of LFLG-AS group versus 2,2% of events in HG-AS group, onset of left bundle branch was seen in 35% LFLG-AS group and in 19,6% in HG-AS group after TAVR (OR:1,6; 95% CI: 0,4-6,5; p=0,486); (OR:6,4; 95%CI: 0,7-57,6; p=0,096 in univariate analysis); (OR: 2,8; 95%CI:0,8-9,2; p=0,096), none of them was statically significant at the multivariate analysis.
Conclusions: This is the first analysis in our cohort multicentre registry comparing HG-AS versus LFLG-AS patients with same baseline characteristics after TAVR. It emerges that LFLG-AS patients have an improvement after the procedure, comparable to that of patients with HG-AS. This depends mainly from an acceptable mortality in the LFLG-AS group and without any statistical difference between the other group. The LFLG-AS patients improve their systolic ejection fraction after TAVR and have a good prognosis. It is shown that mean gradient decreases as expected more in the HG-LF. Also, results showed that para valvular leak is statistically more frequent in LFLG-AS. In LFLG-AS patients may persist an increased cardiovascular risk after the procedure, tied to a more frequent presentation of left bundle branch block, more frequent onset of atrial fibrillation and they need more pacemaker implant than the classical HG-AS. In conclusion we need more data, in particular a more various cohort to evaluate, to confirm our results and to continue in the follow-up of these patients in the next years.