Personne :
Kalavrouziotis, Dimitri

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Institut universitaire de cardiologie et de pneumologie de Québec, Université Laval
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  • Publication
    Pre- and post-operative stroke volume impact after surgical aortic valve replacement for severe aortic stenosis
    (Elsevier Biomedical, 2020-10-19) Guzzetti, Ezequiel; Poulin, Anthony; Kalavrouziotis, Dimitri; Annabi, Mohamed Salah; Pibarot, Philippe; Clavel, Marie-Annick; Dagenais, François.
  • Publication
    RNA expression profile of calcified bicuspid, tricuspid, and normal human aortic valves by RNA sequencing
    (American Physiological Society, 2016-10-01) Gaudreault, Nathalie; Tremblay-Marchand, Joël; Kalavrouziotis, Dimitri; Droit, Arnaud; Guauque-Olarte, Sandra; Bossé, Yohan; Seidman, Jonathan G.; Pibarot, Philippe; Body, Simon C.; Dagenais, François.; Mathieu, Patrick
    The molecular mechanisms leading to premature development of aortic valve stenosis (AS) in individuals with a bicuspid aortic valve are unknown. The objective of this study was to identify genes differentially expressed between calcified bicuspid aortic valves (BAVc) and tricuspid valves with (TAVc) and without (TAVn) AS using RNA sequencing (RNA-Seq). We collected 10 human BAVc and nine TAVc from men who underwent primary aortic valve replacement. Eight TAVn were obtained from men who underwent heart transplantation. mRNA levels were measured by RNA-Seq and compared between valve groups. Two genes were upregulated, and none were downregulated in BAVc compared with TAVc, suggesting a similar gene expression response to AS in individuals with bicuspid and tricuspid valves. There were 462 genes upregulated and 282 downregulated in BAVc compared with TAVn. In TAVc compared with TAVn, 329 genes were up- and 170 were downregulated. A total of 273 upregulated and 147 downregulated genes were concordantly altered between BAVc vs. TAVn and TAVc vs. TAVn, which represent 56 and 84% of significant genes in the first and second comparisons, respectively. This indicates that extra genes and pathways were altered in BAVc. Shared pathways between calcified (BAVc and TAVc) and normal (TAVn) aortic valves were also more extensively altered in BAVc. The top pathway enriched for genes differentially expressed in calcified compared with normal valves was fibrosis, which support the remodeling process as a therapeutic target. These findings are relevant to understand the molecular basis of AS in patients with bicuspid and tricuspid valves.
  • Publication
    Transcatheter aortic valve implantation in patients with severe aortic stenosis and small aortic annulus
    (Elsevier Biomedical, 2011-08-30) Dumont, Éric; De Larochellière, Robert; Rodés-Cabau, Josep; Kalavrouziotis, Dimitri; Bagur, Rodrigo Hernan; Doyle, Daniel; Pibarot, Philippe
    Objectives: Valve hemodynamics and clinical outcomes among patients with a small aortic annulus who underwent transcatheter aortic valve implantation (TAVI) were examined. Background: The presence of a small aortic annulus may complicate the surgical management of patients with severe aortic stenosis (AS). TAVI is an alternative to aortic valve replacement (AVR) in high-risk patients, but few data exist on the results of TAVI in patients with a small aortic annulus. Methods: Between 2007 and 2010, 35 patients (mean age 79.2 ± 9.4 years) with severe AS and an aortic annulus diameter <20 mm (mean 18.5 ± 0.9 mm) underwent TAVI with a 23-mm Edwards SAPIEN bioprosthesis (Edwards Lifesciences, Inc., Irvine, California). Echocardiographic parameters and clinical outcomes were assessed prior to discharge and at 6, 12, and 24 months. Results: Procedural success was achieved in 34 patients (97.1%). There was 1 in-hospital death. Peak and mean transaortic gradients decreased from 76.3 ± 33.0 mm Hg and 45.2 ± 20.6 mm Hg at baseline to 21.8 ± 8.4 mm Hg and 11.7 ± 4.8 mm Hg post-procedure, respectively, both p < 0.0001. Mean indexed effective orifice area (IEOA) increased from 0.35 ± 0.10 cm2/m2 at baseline to 0.90 ± 0.18 cm2/m2 post-procedure, p < 0.0001. Severe prosthesis–patient mismatch (IEOA <0.65 cm2/m2) occurred in 2 patients (5.9%). At a mean follow-up of 14 ± 11 months, gradients remained low and 30 of the 31 remaining survivors were in New York Heart Association functional class I or II. Conclusions: In high-risk patients with severe AS and a small aortic annulus, TAVI is associated with good post-procedural valve hemodynamics and clinical outcomes. TAVI may provide a reasonable alternative to conventional AVR in elderly patients with a small aortic annulus.
  • Publication
    Rate, timing, correlates, and outcomes of hemodynamic valve deterioration after bioprosthetic surgical aortic valve replacement
    (American Heart Association, 2018-08-13) Mahjoub, Haïfa; Rodés-Cabau, Josep; Kalavrouziotis, Dimitri; Voisine, Pierre; Mohammadi, Siamak; Côté, Nancy; Yanagawa, Bobby; Girerd, Nicolas; Pibarot, Philippe; Juni, Peter; Clavel, Marie-Annick; Verma, Subodh; Puri, Rishi; Dagenais, François.; Mathieu, Patrick; Salaun, Erwan
    Background: The incidence of structural valve deterioration after bioprosthesis (BP) aortic valve replacement (AVR) established on the basis of reoperation may substantially underestimate the true incidence. The objective is to determine the rate, timing, correlates, and association between hemodynamic valve deterioration (HVD) and outcomes assessed by Doppler echocardiography after surgical BP AVR. Methods: A total of 1387 patients (62.2% male, 70.5±7.8 years of age) who underwent BP AVR were included in this retrospective study. Baseline echocardiography was performed at a median time of 4.1 (1.3–6.5) months after AVR. All patients had an echocardiographic follow-up ≥2 years after AVR (926 at least 5 years and 385 at least 10 years). HVD was defined by Doppler assessment as a ≥10 mm Hg increase in mean gradient or worsening of transprosthetic regurgitation ≥1/3 class. HVD was classified according to the timing after AVR: “very early,” during the first 2-years; “early,” between 2 and 5 years; “midterm,” between 5 and 10 years; and “long-term,” >10 years. Results: A total of 428 patients (30.9%) developed HVD. Among these patients, 52 (12.0%) were classified as “very early,” 129 (30.1%) as “early,” 158 (36.9%) as “midterm,” and 89 (20.8%) as “long-term” HVD. Factors independently associated with HVD occurring within the first 5 years after AVR were diabetes mellitus (P=0.01), active smoking (P=0.01), renal insufficiency (P=0.01), baseline postoperative mean gradient ≥15 mm Hg (P=0.04) or transprosthetic regurgitation ≥mild (P=0.04), and type of BP (stented versus stentless, P=0.003). Factors associated with HVD occurring after the fifth year after AVR were female sex (P=0.03), warfarin use (P=0.007), and BP type (P<0.001). HVD was independently associated with mortality (hazard ratio, 2.18; 95% CI, 1.86–2.57; P<0.001). Conclusions: HVD as identified by Doppler echocardiography occurred in one third of patients and was associated with a 2.2-fold higher adjusted mortality. Diabetes mellitus and renal insufficiency were associated with early HVD, whereas female sex, warfarin use, and stented BPs (versus stentless) were associated with late HVD.
  • Publication
    Accès libre
    Transvalvular flow, sex, and survival after valve replacement surgery in patients with severe aortic stenosis
    (Elsevier, 2020-04-28) Bilodeau, Anthony; Guzzetti, Ezequiel; Kalavrouziotis, Dimitri; Zhang, Bin; Couture, Christian; Annabi, Mohamed Salah; Pibarot, Philippe; Clavel, Marie-Annick; Dagenais, François.
    Background : The respective impacts of transvalvular flow, gradient, sex, and their interactions on mortality in patients with severe aortic stenosis undergoing surgical aortic valve replacement (AVR) are unknown. Objectives : This study sought to compare the impact of pre-operative flow-gradient patterns on mortality after AVR and to examine whether there are sex differences. Methods : This study analyzed clinical, echocardiographic, and outcome data prospectively collected in 1,490 patients (544 women [37%]), with severe aortic stenosis and preserved left ventricular ejection fraction who underwent AVR. Results : In this cohort, 601 patients (40%) had normal flow (NF) with high gradient (HG), 405 (27%) NF with low gradient (LG), 246 (17%) paradoxical low flow (LF)/HG, and 238 (16%) LF/LG. During a median follow-up of 2.42 years (interquartile range: 1.04 to 4.29 years), 167 patients died. Patients with LF/HG exhibited the highest mortality after AVR (hazard ratio [HR]: 2.01; 95% confidence interval [CI]: 1.33 to 3.03; p < 0.01), which remained significant after multivariate adjustment (HR: 1.96; 95% CI: 1.29 to 2.98; p < 0.01). Both LF/LG and NF/LG patients had comparable outcome to NF/HG (p ≥ 0.47). Optimal thresholds of stroke volume index were obtained for men (40 ml/m2) and women (32 ml/m2). Using these sex-specific cutpoints, paradoxical LF was independently associated with increased mortality in both women (adjusted HR: 2.05; 95% CI: 1.21 to 3.47; p < 0.01) and men (adjusted HR: 1.54; 95% CI: 1.02 to 2.32; p = 0.042), whereas guidelines’ threshold (35 ml/m2) does not. Conclusions : Paradoxical LF/HG was associated with higher mortality following AVR, suggesting that a reduced flow is a marker of disease severity even in patients with HG aortic stenosis. Early surgical AVR (i.e., before gradient attains 40 mm Hg) might be preferable in these patients. Furthermore, the use of sex-specific thresholds (<40 ml/m2 for men and <32 ml/m2 for women) to define low-flow outperforms the guidelines’ threshold of 35 ml/m2 in risk stratification after AVR.